Footwear Impression Evidence: Detection, Recovery and Examination, SECOND EDITION [2 ed.] 9780849310454, 9780203755587, 9781351447430, 9781351447423, 9781351447447

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Footwear Impression Evidence: Detection, Recovery and Examination, SECOND EDITION [2 ed.]
 9780849310454, 9780203755587, 9781351447430, 9781351447423, 9781351447447

Table of contents :

AWARENESS, DETECTION AND TREATMENT OF FOOTWEAR IMPRESSION EVIDENCE

General Information Regarding Footwear Impression Evidence

Formation of Footwear Impression

Finding Footwear Impressions at the Scene of the Crime

General Treatment of Impressions

PHOTOGRAPHY OF FOOTWEAR IMPRESSIONS

General Crime Scene Photography

Examination Quality Photography

Checklist for Examination Quality Photography

CASTING THREE-DIMENSIONAL FOOTWEAR IMPRESSIONS

Introduction to Casting

Casting Materials

Methods of Casting with Dental Stone

After the Cast is Poured

Casting Footwear Impressions in Snow

The Importance of Casting All Three-Dimensional Impressions

TREATMENT OF TWO-DIMENSIONAL FOOTWEAR IMPRESSIONS

Lifting Two-Dimensional Footwear Impressions

Lifting Impressions Electrostatically

Gelatin and Adhesive Lifting

Other Lifting Materials and Choices

Impressions That are Difficult to Lift

Powdering Impressions

Selection of Proper Lifting Materials

Deformable Impressions

THE ENHANCEMENT OF FOOTWEAR IMPRESSIONS

Specialized Lighting and Forensic Photographic Methods

Physical Methods

Chemical Enhancement

Chemical Methods for Enhancement of Residue Impressions

Chemical Methods for Enhancement of Footwear Impressions in Blood

Sequencing of Enhancement Techniques

Three-Dimensional Impression Enhancement

Use of Computers

FOOTWEAR SIZING

Shoe Sizing and Shoe Sizing Systems

Forensic Considerations

MANUFACTURING PROCESSES OF SYNTHETIC SOLED SHOES

The Footwear Industry

The Molding Process

Molding Processes

The Cut Processes

Recognition of Manufacturing Methods

Some Reasons for Shoes of One Size and Design Varying

KNOWN SHOES OF SUSPECTS AND THE PREPARATION OF KNOWN IMPRESSIONS

Obtaining the Known Shoes From the Suspect

Footwear Databases

Test Impressions of Known Shoes

Summary

WEAR CHARACTERISTICS

Defining Wear Characteristics

Factors Influencing the Wear of Shoe Outsoles

Considerations of Wear Characteristics During Examination

CLASS AND IDENTIFYING CHARACTERISTICS

Class Characteristics

Identifying Characteristics

Characteristics Required for Positive Identification

Changes in Identifying Characteristics as Shoe Wear Continues

COMPARISON OF THE QUESTIONED IMPRESSION WITH KNOWN SHOES

Treatment of the Evidence

Variation and Distortion

Examination of the Questioned Impression

Results

THE FOOTWEAR IMPRESSION EXAMINER IN COURT

What Constitutes an Expert Witness?

What Qualifies a Footwear Impression Examiner as an Expert?

PreTrial Conferences

Presentation of Examination Results in Court

Last Minute Examinations

IMPRESSIONS OF THE FOOT

Introduction

Individuality of the Feet

Known Standards of the Feet

The Examination Process

Case Examples

SOME CASE APPLICATIONS

St. Croix Homicide Case

The New York Gap Homicide

Denver Multiple Homicide Case

The Naperville Case

A New York Serial Robbery/Homicide Case

A South Carolina Homicide

THE FOOTWEAR IMPRESSION EVIDENCE IN THE O. J. SIMPSON TRIAL

References

Glossary

Appendix

Index

Citation preview

FOOTWEAR IMPRESSION EVIDENCE Detection, Recovery, and Examination SECOND

EDITION

CRC SERIES IN PRACTICAL ASPECTS OF CRIMINAL AND FORENSIC INVESTIGATIONS VERNON J. GEBERTH, BBA, MPS, FBINA Series Editor

Practical Homicide Investigation: Tactics, Procedures, and Forensic Techniques, Third Edition Vernon J. Geberth The Counter-Terrorism Handbook: Tactics, Procedures, and Techniques Frank Bolz, Jr., Kenneth J. Dudonis, and David P. Schulz Forensic Pathology Dominick j. Di Maio and Vincent j. M. Di Maio Interpretation of Bloodstain Evidence at Crime Scenes, Second Edition William G. Eckert and Stuart H. James Tire Imprint Evidence Peter McDonald Practical Drug Enforcement: Procedures and Administration Michael D. Lyman Practical Aspects of Rape Investigation: A Multidisciplinary Approach Robert R. Hazelwood and Ann Wolbert Burgess The Sexual Exploitation of Children: A Practical Guide to Assessment, Investigation, and Intervention, Second Edition Seth L. Goldstein Gunshot Wounds: Practical Aspects of Firearms, Ballistics, and Forensic Techniques, Second Edition Vincent J. M. Di Maio Friction Ridge Skin: Comparison and Identification of Fingerprints James F. Cowger Footwear Impression Evidence, Second Edition William J. Bodziak Principles of Kinesic Interview and Interrogation Stan Walters Practical Fire and Arson Investigation, Second Edition David R. Redsicker and John J. O'Connor The Practical Methodology of Forensic Photography David R. Redsicker Practical Gambling Investigation Techniques Kevin B. Kinnee Practical Aspects of Interview and Interrogation David E. Zulawski and Douglas E. Wicklander Practical Investigation Techniques Kevin B. Kinnee Investigating Computer Crime Franklin Clark and Ken Diliberto Practical Homicide Investigation Checklist and Field Guide Vernon J. Geberth Bloodstain Pattern AnaWsis: With an Introduction to Crime Scene Reconstruction Tom Bevel and Ross M. Gardner Practical Aspects of Munchausen by Proxy and Munchausen Syndrome Investigation Kathr)m Artingstall

FOOTWEAR IMPRESSION EVIDENCE Detection, Recovety, and Examination SECOND

EDITION

J. Bodziak Supervisory Special Agent (retired) Laboratory Division Federal Bureau of Investigation Washington, D.C.

lC)

CRC Press Taylor &. Francis Group Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

The cover depicts an enlarged photograph of a portion of the metal show mold at the Silga factory in Italy. This mold was the same one used to make the soles for the size 12 Bruno Magli shoes that deposited the bloody shoe impressions on the walkway at 875 S. Bundy Drive.

Library of Congress Cataloging-in-Publication Data Bodziak, William J. Footwear impression evidence : detection, recovery, and examination / William J. Bodziak. — 2nd ed. p. cm. — (CRC series in practical aspects o f criminal and forensic investigations) Includes bibliographical references and index. ISBN 0-8493-1045-8 (alk. paper) 1. Footprints— Identification. 2. Footwear— Identification. 3. Criminal investigation. I. Title. II. Series. HV8077.5.F6B63 1999 362.25'62— dc21

99-28347 CIP

This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage or retrieval system, without prior permission in writing from the publisher. The consent of CRC Press LLC does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from CRC Press LLC for such copying. Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. Visit the CRC Press Web site at www.crcpress.com © 2000 by CRC Press LLC No claim to original U.S. Government works International Standard Book Number 0-8493-1045-8 Library of Congress Card Number 99-28347

Series Editor's Note

This textbook is part of a series entitled “Practical Aspects of Criminal and Forensic Investigation”. This series was created by Vernon J. Geberth, a retired New York City Police Department Lieutenant Commander, who is an author, educator, and consultant to homi­ cide and forensic investigations. This series has been designed to provide contemporary, comprehensive, and pragmatic information to the practitioner involved in criminal and forensic investigations by authors who are nationally recognized experts in their respective fields.

Preface (First Edition)

Shoes are fascinating items of clothing. They are made in a variety of ways and in thousands of designs. In turn, each design is made in many distinguishable sizes. As the outsole wears, their design and other characteristics steadily change. They acquire cuts, scratches, nicks, and other characteristics of a random nature. These traits serve to give them a tremendous degree of individuality. As they track through soil, snow, sand, residue, and other materials, supporting the weight of their wearer, they impress their distinct and individual features on or into the surfaces over which they pass. Items of footwear and their impressions that remain at the crime scene offer sound, reliable, and demonstrative evidence of a person’s presence. Yet, despite the fact that footwear impressions are present at most crime scenes, they still constitute only a small fragment of the physical evidence that crime scene technicians collect and that investigators and prosecutors use in the proof of facts. In searching for some explanations as to why footwear impression evidence has not received greater emphasis, my experience and tenure in this area since 1973 have led to certain observations and deductions. First, in the development and growth of laboratories throughout the world, the respon­ sibilities for the examination of footwear impression evidence have historically fallen to several different disciplines. Some laboratories designated their fingerprint examiners to examine this evidence, reasoning that a “footprint” and a fingerprint examination must be alike. This, in addition to the convenience that most laboratories already employed fingerprint examiners, resulted in footwear impression examinations becoming part of many latent fingerprint examiners’ responsibility. Likewise, some laboratories designated their document examiners to examine footwear impressions. Their reasoning was that a “shoe print,” like a rubber stamp examination, was clearly the same as a document printing examination. Other laboratories designated their toolmark and firearms examiners to examine footwear evidence. Even laboratory examiners designated as criminalists, microscopists, trace analysts, and chemists have, in certain instances, been assigned the respon­ sibility of footwear impression evidence. As a result of this treatment of this evidence as just an “occasional examination” that could be conveniently handled by persons in other disciplines, footwear impressions, during the further development of laboratories and the growth in recent years in the forensic sciences, have not been given the necessary emphasis and attention that they deserve and need. Fingerprint examiners, document examiners, toolmark examiners, and the like, who spent the overwhelming majority of their time in their respective primary forensic disciplines, were unable to dedicate the necessary time and resources toward the examination of footwear impression evidence. Likewise, the topic of footwear impression evidence was less frequently discussed at forensic science meetings of those groups and was less published in their respective journals.

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Footwear Impression Evidence, 2nd Edition

This second-rate treatment of footwear impression evidence by laboratory and crime scene personnel spilled over into the investigative and judicial areas as well. Footwear impression evidence was seldom looked for at crime scenes and when found, was seldom examined and utilized to its fullest extent. Consequently, investigators and prosecutors rarely had reason to understand and appreciate the full importance of that physical evi­ dence and failed to utilize it in the proof of facts of their case. Fortunately, this is changing. In recent years there have been numerous seminars, published articles, and presentations covering the collection and examination of footwear impression evidence. Footwear impression evidence is being utilized with increasing frequency throughout the world. At the same time, changes in technology have assisted in helping to retrieve this type of evidence from the crime scene. The improvement, development, and availability of the electrostatic lifting device and quality gelatin footprint lifters; the use of dental stone casting materials; better film and camera technology; and the increased application of both old and new enhancement techniques and materials have greatly contributed toward the suc­ cessful detection and utilization of footwear impression evidence. In addition, the past years have witnessed dramatic world changes in the footwear industry. Literally thousands of shoe designs, each available in many sizes, are available to the consumer nowadays. The shoes people wear are also more likely to have synthetic outsoles. Those outsoles, in turn, are more likely to acquire detectable characteristics and to leave traces of their impression at the crime scene. In order to fully utilize this evidence, footwear examiners need to be knowledgeable and experienced in all facets of this evidence, including the proper methods of detecting and retrieving footwear impressions at the crime scene, the photography and enhancement of those impressions, the manufacturing of footwear, and the evaluation of footwear evidence being examined. Any weak link concerning the discovery, recovery, examination, and proper utilization as evidence in court will adversely affect the usefulness and success of this evidence. For that reason, it is also crucial that examiners be actively involved in passing this knowledge along to their colleagues, including crime scene technicians, inves­ tigators, and prosecutors. Today’s footwear examiner cannot be satisfied to know that footwear impressions were found at only a small fraction of their crime scenes when common sense dictates that more are present. I am aware of a few laboratories that in recent years have finally given due emphasis to footwear evidence. They have insisted that their crime scene technicians preserve the crime scene and aggressively search for footwear impressions. And, to their surprise, they found that they were detecting many more impressions than before. Their examiners have since conducted more examinations that have not only given them more experience but have allowed them to justify and dedicate more time toward casework and training in this area. As a result, more cases have been solved and more court trials were won due to the contribution that evidence made. Since first being assigned to the FBI laboratory in 1973, I had steadily accumulated casework experience, reference materials, photographs, and other information concerning footwear impression evidence. That effort intensified in 1982 and thereafter when I began participating in seminars hosted by other forensic laboratories, interacted with other footwear examiners, and began organizing footwear impression seminars and classes at the FBI Academy in Quantico, Virginia. The result was a large accumulation of information concerning the materials and procedures that were essential in locating and collecting

Preface (First Edition)

LX

footwear impression evidence at the crime scene, as well as the comparison of a suspect s shoes with the questioned impression evidence. Drawing upon that information and experience, I have written this book. I hope its contents will provide the necessary information and incentive to those in the law enforcement community to become more aware of and to better utilize footwear impression evidence.

Preface (Second Edition)

The responses received since writing the first edition of this book have been very supportive. Now, with additional information and newly reported techniques, it is appropriate to expand, update, and improve the original 12 chapters. In addition, this second edition contains three new chapters. Chapter 13 concerns the examination of barefoot evidence. Footwear examiners often encounter this form of evidence. Although the topic warrants a book of its own, this chapter presents the basic information to introduce the reader to this evidence as well as some case applications. Chapter 14 provides some actual case applications of examples of footwear impression evidence, to re-emphasize the importance of its recovery and examination. And finally, in Chapter 15, the footwear examination efforts and conclusions in the O. J. Simpson criminal and civil cases are presented. Since writing the first edition, I have been fortunate to have gained valuable knowledge and experience through interaction with examiners across the U.S. and in numerous other countries. Visits to forensic laboratories in Australia, Canada, Estonia, Finland, Germany, Hungary, Japan, New Zealand, Poland, and Switzerland have broadened my knowledge of the application and practices in this area of examination. Increased communications among footwear examiners on an international level, as well as an increase in the meetings and organizations covering this topic area, have been significant. In 1994, the Federal Bureau of Investigation hosted the International Symposium on Footwear and Tire Tread Impression Evidence at the FBI Academy at Quantico, Virginia. This event was attended by 230 examiners representing 30 countries. In 1995, the first European Meeting of Foot­ wear and Toolmark Examiners was hosted by Finland’s National Bureau of Identification in Vantaa, Finland. This organization met again in The Netherlands in 1997 and in Stock­ holm, Sweden in 1999 and is growing rapidly, with meetings scheduled every other year. In 1997, the first European Meeting of Forensic Science was hosted by the University of Lausanne, Switzerland, a section of which was dedicated to footwear, tire, and toolmark examinations. And in 1998, the International Association for Identification established the first certification program for footwear examiners, outside local programs that may exist in individual laboratories. Footwear impressions are being located and identified today, which just a few years ago would not have ever been discovered at the scene of the crime, or if found, would not have been utilized to their fullest extent. Newer techniques, methods, and materials to recover, enhance, and increase the utilization of this valuable form of physical evidence will undoubtedly continue to be developed in the future. Although the interest and aware­ ness of this evidence has improved dramatically over recent years, there are still some departments and crime scene units whom, regretfully, have not developed aggressive and structured practices to find and utilize this evidence to its fullest extent. There is no doubt in my mind that this is rapidly changing. My interaction today, with individual investigators and crime scene technicians, reflects an abundance of knowledge and understanding of

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this evidence, that just a few years ago, was not present. Many laboratories now have examiners whose time is dedicated strictly to impression and mark evidence. The increased emphasis in this field, accompanied by additional research and training, will assure that the future utilization of this evidence will continue to rise to its potential.

About The Author

William J. Bodziak retired in December 1998, after serving with the Federal Bureau of Investigation for 29 years. He continues to work as a forensic consultant. Mr. Bodziak is a native of Washington, D.C., where he received his early education. He was appointed as a Special Agent with the FBI in 1970. He served in an investigative capacity in the FBI offices in New Haven, Connecticut, Baltimore and Hyattsville, Maryland, and in Jackson­ ville, Florida. From 1973 until 1997, he was assigned to the FBI Laboratory in Washington, D.C. During this time, he conducted forensic examinations of questioned documents, footwear and tire tread impressions, examining evidence in thousands of cases and con­ tributing his efforts to numerous major investigations. He has testified as an expert in federal courts and state and local courts throughout the U.S., and has also given expert testimony in courts in Guam, Puerto Rico, the U.S. Virgin Islands, and Canada. He has lectured and taught on topics related to the examination of footwear and tire tread impres­ sion evidence to examiners at the FBI Laboratory, at the FBI Academy (Quantico, Virginia), at the FBI International Law Enforcement Academy (Budapest, Hungary), and at numerous seminars and conferences throughout the U.S. and internationally. Mr. Bodziak holds an AB Degree in Biology from East Carolina University in Green­ ville, North Carolina, and a Masters of Science in Forensic Science degree from the George Washington University in Washington, D.C. He is a Fellow of the American Academy of Forensic Sciences, a member of the American Society of Questioned Document Examiners, and is a Certified Diplomate of the American Board of Forensic Document Examiners. He has been certified by the FBI Laboratory in the areas of questioned document, footwear, and tire tread examination. In addition, he is a member of the International Association for Identification where he is a certified footwear impression examiner and for which he has served as the Chairman of the Footwear and Tire Track section.

Xlll

Acknowledgments

Many persons who provided support and assistance in the preparation of the first edition of this book were acknowledged in that edition. Since much of that work is represented in this edition, 1 would again like to extend my appreciation to James C. Burggraff, Roger T. Castonguay, Sharon Clayborne, James Gerhart, Ernest D. Hamm, Dawn D. Hester, John W. Hicks, Kathleen W. Johnson, Danny L. Keen, James E. Lile, William W. Magle, John F. Paulisick, William H. Peters, Gerald B. Richards, Richard R. Thomas, Cynthia Ann Turcea, Colleen Wade, and William L Wempe. Special thanks to Dr. Irving H. Miller, who provided much of the information concerning the human foot in Chapter 9. Many additional individuals offered their assistance or made significant contributions to this second edition. My sincere appreciation to Jeffrey T. Bell, Kevin Brown, Kjell Carllson, Michael Chase, Roger J. Davis, Frank W. Fawcett, Robert W. Fawcett, John F. Fischer, Eugene Giles, Eric Gilkerson, Alexandre Girod, Herb Hedges, Sara Jones, Horst Katterwe, Isaac Keereweer, Heikki Majamaa, Noel Paine, Daniel R. Potter, Yaron Shor, Michael B. Smith, Tim Trozzi, Yvette Trozzi, Ronald L. Valmassy, M. J. M. Velders, Sandra Wiersema, and Jan N. Zonjee. And thanks to numerous others, whose research, presenta­ tions, published papers, and work in this field have contributed to this edition. For their interest, support, and encouragement over the many nights and weekends that I spent on the first and second editions, my love and appreciation go to my wife Shirley, and to my children Bill, Leslie, and Chuck.

XV

Table of Contents

Awareness, Detection, and Treatment of Footwear Impression Evidence General Information Regarding Footwear Impression Evidence Formation of Footwear Impressions Finding Footwear Impressions at the Scene of the Crime Genera] Treatment of Impressions

7 17 24

Photography of Footwear Impressions

27

General Crime Scene Photography Examination Quality Photography Checklist for Examination Quality Photography

27 30 57

Casting Three-Dimensional Footwear Impressions

59

Introduction to Casting Casting Materials Methods of Casting with Dental Stone After the Cast is Poured Casting Footwear Impressions in Snow The Importance of Casting all Three-Dimensional Impressions

59 65 72 81 84 96

Treatment of Two-Dimensional Footwear Impressions

99

Lifting Two-Dimensional Footwear Impressions Lifting Impressions Electrostatically Gelatin and Adhesive Lifting Other Lifting Materials and Choices Impressions that are Difficult to Lift Powdering Impressions Selection of Proper Lifting Materials Deformable Impressions

The Enhancement Of Footwear Impressions Specialized Lighting and Forensic Photographic Methods

xvii

1

99 102

116 122

124 126 126 127

135 135

Footwear Impression Evidence, 2nd Edition

X V llJ

Physical Methods Chemical Enhancement Chemical Methods for Enhancement of Residue Impressions Chemical Methods for Enhancement of Footwear Impressions in Blood Sequencing of Enhancement Techniques Three-Dimensional Impression Enhancement Use of Computers

6

Footwear Sizing Shoe Sizing and Shoe Sizing Systems Forensic Considerations

7

Manufacturing Processes of Synthetic Soled Shoes The Footwear Industry The Molding Process Molding Processes The Cut Processes Recognition of Manufacturing Methods Some Reasons for Shoes of One Size and Design Varying

8

Wear Characteristics Defining Wear Characteristics Factors Influencing the Wear of Shoe Outsoles Considerations of Wear Characteristics During Examination

10

11

179 179 184

197 197 198 210 237 277 277

Known Shoes of Suspects and the Preparation of Known Impressions 279 Obtaining the Known Shoes from the Suspect Footwear Databases Test Impressions of Known Shoes Summary

9

140 145 145 160 174 175 176

class and Identifying Characteristics

279 284 285 306

307 307 307 319

329

Class Characteristics Identifying Characteristics Characteristics Required for Positive Identification Changes in Identifying Characteristics as Shoe Wear Continues

329 335 347 353

Comparison of the Questioned Impression with Known Shoes

357

Treatment of the Evidence Variation and Distortion Examination of the Questioned Impression Results

357 362 365 372

Table of Contents

12

The Footwear Impression Examiner in Court What Constitutes an Expert Witness? What Qualifies a Footwear Impression Examiner as an Expert? Pretrial Conferences Presentation of Examination Results in Court Last Minute Examinations

13

Impressions of the Foot Introduction Individuality of the Feet Known Standards of the Feet The Examination Process Case Examples

14

Some Case Applications St. Croix Homicide Case The New York Gap Homicide Denver Multiple Homicide Case The Naperville Case A New York Serial Robbery/Homicide Case A South Carolina Homicide

15

XIX

375 375 375 377 377 379

381 381 382 392 397 408

413 413 416 418 422 425 427

The Footwear Impression Evidence in the O. J. Simpson Trial

431

References

459

Glossary

475

Appendix

483

Index

487

Dedication

To my wife, Shirley, for her love, understanding, patience, and support.

And to my Mother, for all her caring love.

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Awareness, Detection, and Treatment of Footwear Impression Evidence

1

W herever he steps, whatever he touches, whatever he leaves even unconsciously, will serve as silent w itness against him . N ot on ly his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool marks he leaves, the paint he scratches, the blood or sem en he d ep osits or collects — all o f these and m ore bear m ute w itness against him . This is evid en ce that does not forget. It is not confused by the excitem ent o f the m om en t. It is not absent because hum an w itnesses are. It can n ot perjure itself. It cannot be w h olly absent. O nly its interpretation can err. O nly hum an failure to find it, study and understand it, can dim inish its value.

Paul L. Kirk (deceased)

Crime Investigation, 2nd ed., /. /. Thornton, ed., 1974, p. 2.

General Information Regarding Footwear Impression Evidence Im pression Evidence Impression evidence can be generally defined as ''objects or materials that have retained the characteristics of other objects or materials through direct physical contact^ Many forms of impression evidence are encountered in forensic work, including fin­ gerprints, palm prints, footwear impressions, tire impressions, bite marks, glove prints, bare footprints, socked foot impressions, firing pin impressions, lip impressions, ear impressions, contusion and abrasion pattern injuries, typewritten impressions, and rubber stamp impressions. Perhaps the oldest forms of impressions are plant and animal fossils, whose features were captured as they were impressed into layers of the surrounding rock and soil, now offering absolute proof of their existence. Footwear Impressions: A Valuable Form of Physical Evidence Crimes involve people and places. Persons committing a crime leave footwear impressions en route to, at, and exiting from the crime scene. As a form of physical evidence, footwear impressions provide an important link between the criminal and the place where the crime occurred. Yet, although footwear impressions are found at many crime scenes, the quantity found is far less than those which are actually present. They are located in only a smaU

1

2

Footwear Impression Evidence, 2nd Edition

percentage of cases compared to that in which they likely exist. Failure to locate and recover this evidence is not forgivable, but there are some reasons that may explain why more is not found. The location of footwear impression evidence, primarily on ground surfaces, makes it sometimes difficult or inconvenient to find, particularly if the impressions are latent or nearly invisible. Specialized lighting techniques are often required along with an aggressive effort to find the impressions. Many crime scene technicians have had little or no experience in searching for these types of impressions. In other instances, they simply may not have dedicated the time and effort needed to search for this evidence. In addition, the footwear impressions of the subject may be mixed with those of other persons, such as paramedics and investigators, who may have arrived at the scene ahead of the crime scene technician. The fact that there may be footwear impressions of others mixed with those of the suspect does not necessarily mean that the suspect's were destroyed, yet many technicians are discouraged by such tracked over areas and mistakenly abandon any efforts to look for impressions. Footwear impression evidence has also been frequently undervalued by investigators, attorneys, and the courts due to their limited knowledge of it. Investigators still occasionally ask the question, "What can you determine by comparing a footwear impression with a shoe?" And it is still not unheard of, in cases where a positive identification is made, to be asked, "Can you really say that shoe positively made that impression? " The long-term effect of this limited knowledge and utilization of footwear evidence is often a further discouragement and deterrent for the crime scene officer to look for footwear impressions. Additionally, because footwear evidence often is latent or nearly invisible, the crime scene technician may erroneously feel that it is not present or, by not thoroughly looking, may even rationalize its believed non-existence. Information regard­ ing this evidence should be implemented in any forensic training program or law enforce­ ment training syllabus. It is imperative that crime scene technicians and investigators be aware of the full importance of footwear impressions as physical evidence. When securing the crime scene area, they must preserve all forms of evidence, including footwear impressions. Before beginning the crime scene search, careful thought should be given to understanding what occurred at the crime scene, how footwear impression evidence would be relevant and could contribute to the proof of facts, and what areas of the crime scene might be the most logical to check first for footwear impressions. Then the footwear impressions should be aggressively and carefully looked for. What is not looked for will not be found! Frequency of Footwear Im pressions Each time a person takes a step, their footwear is impressed against the ground and can cause a deformation of that substrate or result in the transfer of trace materials and residue from the shoe to the substrate. Because of the direct physical contact under the weight of the wearer, there is no doubt that some type of interaction between the shoe and the substrate occurs with each and every step. Although not all of the impressions will be visible or detectable, the chances are excellent that a great many of them will be. If a crime occurred in an area where the ground was soft, such as a sandy beach or on a soft dirt road, no one would contest the common sense deduction that footwear impres­ sions would be present. It would be simply impossible for the subject to step in those areas

Awareness, Detection, and Treatment of Footwear Impression Evidence

3

without leaving many impressions in the soft surface. If that same crime were to have taken place at another location with a different surface, one would not necessarily assume the presence of footwear impressions. However, the fact is the subject’s shoes would have impressed themselves against the ground's surface just as many times, allowing an excellent chance that one or more of those impressions could be located and retrieved. Today, everyone accepts the potential for the presence of latent fingerprints at a crime scene. Unfortunately, it is often not recognized that there is an equal and perhaps even greater chance that footwear impressions could be present as well. The average investigator could list many possible reasons why fingerprints would be left at a crime scene and their probable locations. The same investigators are not usually as knowledgeable about footwear impressions. Yet with every step that is taken, whether on soil, snow, concrete, a tile floor, carpeting, glass, a wooden window sill, a piece of paper, a bank counter, or on countless other objects and materials, a representation of the characteristics of the shoe sole can be impressed against and retained by that surface, in either a visible form, or in a latent form that can later be visualized. For anyone who has not had the success of locating many footwear impressions at the scene of a crime and is not yet convinced that there are more footwear impressions present than those that are blatantly obvious, two examples are offered. A recent study conducted in several jurisdictions in Switzerland' disclosed that footwear impressions were located at approximately 35% of all crime scenes. The crimes investigated in those areas consisted primarily of burglaries. Communication from another fellow examiners reported that in the past three years, after re-emphasizing to crime scene personnel and teaching the basics of locating and recovering footwear impressions, the percentage of cases in which footwear impression evidence was now being submitted to their laboratory had increased from less than 5% to approximately 60%.^ Durability of Footwear Im pressions Footwear impressions are either permanent or can be permanently recorded. Footwear impressions at crime scenes are of sufficient durability to allow for their discovery, retrieval, recording, and examination. In fact, their durability and permanence in some cases is surprising. Age of Im pressions The life expectancy of footwear impressions can range from a brief moment to years. There is often evidence or circumstances which allow the logical deduction of facts relating to the age of an impression. There is no way, however, to analyze a footwear impression and determine its precise age. Any deductions that involve age determination must be based on common sense and other factors known to exist in conjunction with the impression. Exterior impressions in snow, sand, and soil will begin to deteriorate after they are made. The speed and extent of that deterioration will depend on time, weather factors such as ‘ Girod,A. Presentation at the European Meeting for Shoeprint/Toolmark Examiners, The Netherlands, April, 1997. ^ Kelderman, M., Personal communication. Environmental Sciences Research Ltd., Auckland, New Zealand, March 1997.

Footwear Impression Evidence, 2nd Edition temperature, wind and rain, destruction by other shoes or tires, and the makeup of the substrate. Impressions in blood can last for years unless on exterior surfaces. Likewise, impressions in residue or dust will last for years unless the surface is cleaned or physically altered. Impressions on some surfaces that are routinely traveled over or cleaned will have a shorter life span. For instance, a footwear impression on a bank counter will be, in all likelihood, less than 24 hours old, since most bank counters are routinely cleaned and polished at least once every day. Positive Identification of Footwear In many instances, footwear impressions can be positively identified as having been made by a specific shoe to the exclusion of all other shoes. This identification is based on a physical match of random individual characteristics the shoe has acquired with those respective features in the impression. The identification is as strong as that of fingerprints, toolmarks, or typewritten impressions. In other instances, the degree of detail retained in a footwear impression may not be sufficient to detect those random individual characteristics necessary to "positively" identify a specific shoe. However, the detail that is present may still be very significant. The combined size and design characteristics of the shoes alone, as explained in later chapters, are so numerous and diverse when diluted among the approximately 1.5 billion shoes sold annually in the U.S., that any specific size and design of shoe, without regard to wear or other characteristics, will be owned by only a very small fraction of 1% of the general population. Additional factors, such as manufacturing variations and wear, although not sufficient alone to enable positive identification, can significantly further reduce the num­ ber of other shoes that could have made the impression. Inform ation Provided by Footwear Im pressions Footwear impressions can reveal, in many cases, the type, make, description, and approx­ imate or precise size of the footwear that made them. This information can often assist in the process of developing a suspect. In addition, the location of footwear impressions at the scene can often help in reconstruction of the crime. The presence, characteristics, and condition of the impressions may assist in determining the number of suspects, their path into, through, and away from the crime scene, their involvement in the crime, and the events that occurred during the crime. Footwear impressions at crime scenes can also be used to corroborate or refute infor­ mation provided by witnesses or suspects. As an example, in one homicide case, a person exited his residence in the snow and broke into his own house through a basement window. He was staging a false crime as an alibi to the murder of his wife, which he had just committed, and was claiming himself as a victim as well. The detective investigating the case noticed that the shoe prints in the snow exited the rear door and led to the basement window, an unlikely path based on the alibi and one that proved that person was lying. In another case, the absence of any footwear impressions in the recently fallen snowcovered ground around a house implied that the crime was committed by someone in the house.

Awareness, Detection, and Treatment of Footwear Impression Evidence

5

Gait Characteristics Gait analysis is the system atic study o f hum an walking. It is often helpful in the m edical m anagem ent o f those diseases w hich affect the lo co m o to r system . N orm al hum an w alking and running can be defined as “a m eth od o f lo c o m o tio n involving the use o f two legs, alternately, to provide both su p p ort and propulsion.” ^

Terms are used to describe the placement of the feet on the ground. They include stride length, which is the linear distance between two successive steps of the same foot, and step length, which is the linear distance that one foot moves in front of the opposite one. The step length may be different for the left and right feet. The stride width, also known as the walking base, is the transverse distance between the left and right foot impressions measured perpendicular to the direction traveled. It is measured at the mid-point of the heel. The foot angle, also known as the toe-out or toe-in, is an angular measurement of the mid-line of the foot in relation to the direction of travel.'^ These basic distances are illustrated in Figure 1.1. Many criminalistic texts and articles written on footwear impressions have suggested or outlined methods for recording information relating to a person’s gait. My experiences have been that footwear impressions left at crime scenes do not offer a reliable succession of impressions to make use of this type of information. However, even if a crime scene were to include a number of succeeding impressions that might appear to represent the “ordinary gait” of the perpetrator, it is not possible to know if these impressions were, in fact, the result of normal walking or the result of running or walking fast. In addition, the recorded steps could have been influenced by some external factor which would preclude a recording of the normal gait of the person leaving them. Likewise, when taking known standards of the suspect s gait, it would not be possible to know whether that person should be directed to walk, walk fast, or run. With each minor change, the gait characteristics would change and could therefore be erroneously evaluated. Studies have been made of human locomotion and gait regarding the speed and duration of the walking cycle and the duration of the temporal components of the walking cycle. Other studies have been made regarding the influence of walking speed on the gait pattern and have concluded that with increased walking speed, the stride length and stride width were increased but the out-toeing angle decreased.^ Thus, it is normal for gait characteristics to vary within the same individual Further, studies regarding the coefficient of friction as it relates to the slip resistance of shoes have been conducted and offer other reasons for gait to vary within the same individual. One such study regarding the coefficient of friction vs. top-piece/outsole hard­ ness and walking speed concluded that outsole and top-piece hardness or flexibility of '^Whittle, M. W., Gait A nalysis, Butterworth-Heinemann, Oxford, England, 1996. '‘ Whittle, M. W., G ail Analysis, Butterworth-Heinemann, Oxford, England, 1996, pp 61-62. ^Murray, M.P., Drought, A.B., and Kory,R.C. Walking patterns of normal men. J.Bone e) ¡oint Smg., 46-A: 335-360, 1964. ^Drillis, R.J. Objective recording and biomechanics of pathological gait. Ann. New York Acad. Sci., 74:86109, 1958. ^Smith,K.U., McDermid,C.D., and Shideman,F.£. Analysis of the temporal components of motion in human gait. Am. I. Phys. Med., 39:142-151, 1960. ^ Murray, M.R, Kory, C., Clarkson, B.H., and Sepic, S.B., Comparison of the free and fast speed walking patterns of normal men. Am. /. Phys. Med., 45 (l]:8-24, 1966.

Footwear Impression Evidence, 2nd Edition

Human gait measurements

Figure 1.1

H u m a n gait m ea su rem en ts.

footwear may affect forefoot flexibility, which may in turn affect stride length and gait dynamics.*^ Further, this study concluded that other factors, such as the type and condition of the surface walked upon, caused differences in the kinetics and kinematics of walking as the subjects in the study adapted to the various aspects of the walkway surfaces. Examples of this which are experienced in everyday life would be conscious or subconscious changes of gait characteristics as we walk over a slippery surface or through soft sand. Knowledge and observance of gait characteristics, when they are present on exterior surfaces, are used in the tracking of individuals by expert trackers, like those with the U.S. Border Patrol (Kearney, 1983). The gait information is not used alone, but along with shoe ^ Fendley, A.E. and Medoff, H.R Required coefficient of friction versus top-piece/outsole hardness and walking speed: Significance and correlations. /. Forensic S et, 41(5):763-769, 1996.

Awareness, Detection, and Treatment of Footwear Impression Evidence

7

designs and other tracking signs to effectively track illegal immigrants, missing children, and criminals. Tracking is an appropriate application of this type of information, since the tracker is not relying on this information as a means of personal identification but to locate the logical position of successive steps and to distinguish that person from others whose paths may have crossed the same area. The gait characteristics of a person are not individual identifying ones but are, at best, only class characteristics of persons sharing a similar gait pattern. In summary, the gait characteristics of footwear impressions at crime scenes, partic­ ularly impressions on confined interior surfaces, may have some significance, but cannot be used to establish the personal identity of a subject.

Forensic Scent Recognition Dogs specifically trained to recognize and compare human scent have long been used for searching and tracking a scent line laid by a human. In some countries, the extremely sensitive olfactory senses of dogs are also used to associate human scent, collected from the crime scene, with the collected scent of s u s p e c t s . T h i s technique is used primarily for investigative assistance, and not for absolute identification. Odors, collected from the crime scene footprints of the perpetrator, are collected by covering the footprint with a specially prepared sterile cloth. The cloth is then placed in a sterile glass jar. Later, similarly prepared cloths, containing the odors of the suspect and other persons, are spaced several feet apart from one another, in a line-up fashion. First, the dog handler allows the dog to smell the odor collected from the scene. Then, the dog is unleashed and allowed to smell the contents of the other jars. The dog will lie down or bark in front of the jar in the case of an identification. The same procedure will be repeated after removing the jar containing the suspect s odor. The dog will then be allowed to repeat the process and should have a negative response.*^

Formation of Footwear Impressions Several things can occur when a shoe makes contact with the ground. They include the creation of static charges, the deformation of the surface, and the transfer of residue or trace materials between the shoe and the surface.

Creation of Static Charges When a shoe is impressed against a surface, it can create an electrostatic charge on that surface (Davis, 1988). This can be demonstrated by wearing clean, dry shoes, taking several steps and then walking across and stepping on a hard flat surface such as a tile floor. If several light puffs of black blower p o w d e r a r e then applied to the area, the powder will Keereweer, 1., Ministry of Justice, Forensic Science Laboratory, Rijswijk, The Netherlands, personal communication, 1998. ” de Bruin, J. C., Police Dog Training Institute, Rotterdam- Rijnmond, The Netherlands, personal com m u­ nication, 1998. ^^de Bruin, j. C., '"The Detection Dog and Science", Dog Training Centre, Rotterdam - Rijnmond Police Force, The Netherlands. ODV, South Paris, Maine.

8

Footwear Impression Evidence, 2nd Edition

be attracted to the residual static charge left by the impression, and a visual image will result (Figure 1.2A). Likewise, if a clean, dry shoe was used to step on carpeting, an application of small polystyrene beads would result in the visualization of the impression because the beads are attracted to the residual charge created by the impression. Unfortu­ nately, the residual static charge does not last long and is not demonstrable in high humidity or damp environments. It is not useful nor practical for applications at crime scenes. Static charges, in part, account for the strong adherence of residue, dust, and other trace materials that are transferred from the shoe to the surface. D eform ation of the Surface If the ground surface is soft and yields to pressure exerted by the shoe, that surface will deform, either temporarily or permanently, and may retain the characteristics of the shoe. If the surface is snow, sand, soil, or a similar material, the impression will be a relatively permanent three-dimensional deformation. If the surface is resilient, such as carpet, grass, or skin, the deformation caused by the impression will be temporary, although some permanent two-dimensional marks or damage, such as stains, contusions, or the transfer of residue, may occur in conjunction with these impressions. One interesting and innovative method of showing footwear impressions on resilient carpeting involved the use of holography to record the outline of a footwear impression (Bradford, 1976). When stepped upon, carpet is crushed; however, over a period of time, it slowly returns to its original shape. As the carpet fibers rebound, the holograph is able to distinguish minute movements of the carpet's fibers during the time between two separate exposures, enabling it to visualize the general shape of the footwear impression. This method of detection is, of course, not practical or possible at crime scenes, but again demonstrates the formation and resiliency of these impressions. Transfer of Trace or Residue Materials With many two-dimensional impressions, there is a transfer of trace materials or residue between the footwear and the substrate. An impression that results when a shoe deposits material onto a substrate is a positive impression, one in which the residue visually represents the areas of the sole that actually came in contact with the ground surface. The impressions in Figures 1.3C, 1.4B, and 1.5A are examples o f positive impressions. Positive impressions constitute the most common form of two-dimensional impressions. A negative impression is produced when the contact areas of a shoe remove residue from a surface and in which the residue on the surface remains where the areas of the sole did not come in contact with the surface. Figures 1.3A and 1.3B provide examples of negative impressions. Negative impressions occur less frequently than positive impressions. Two-dimensional impressions can occur when the shoes are wet or dry and can occur on a large variety of receiving surfaces. A dry origin impression is one in which the shoe and the receiving surface are dry at the time the impression is made. A wet origin impression is one that is made when either the shoe and/or the receiving surface is damp or wet at the time the impression is made. Some examples of the many possibilities are discussed. Clean dry shoes on dry surfaces. Non-leather soles or heels are composed of many complex compounds such as polyurethane, polyvinyl chloride, ethyl vinyl acetate, and other synthetic rubber compounds. Trace materials from, or absorbed or ground into, the soles can be deposited onto the surface in minute quantities. Therefore, a shoe with an

Awareness, Detection, and Treatment of Footwear Impression Evidence

.

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Figure 1.2

A footw ea r im p ressio n in a dry e n v ir o n m e n t w ill create a sta tic charge th a t can be v isu a lized by ap plyin g a fin e pow der or to n er across th e surface. T h is im p ressio n (A) w as a la ten t sta tic charge on a floor over w h ich several puffs of b lo w er fingerprint pow der w ere applied. T h e pow der adhered to th e charged areas of th e fo o tw ea r im p ressio n .

apparently clean sole can still leave a trace of its impression on paper items, pieces of glass, and polished surfaces by depositing these trace materials. The physical contact of a clean shoe on paper items can result in impressions that can be developed chemically and physically. Figure 1.2B shov/s the developed latent footwear impressions on paper which were chemically treated with physical developer. Later, in Chapter 4, methods to develop latent indentations of footwear impressions on paper, in the same way that indented handwriting is developed, are discussed. Clean footwear can also leave an impression in the residue or film that is left on surfaces through the accumulation of waxes, oils, or dirt. This is seen most frequently on nonporous and polished surfaces. Flooring, exterior sides of glass, and polished countertops often contain a film of wax, residue, or dirt and therefore are good candidates for retaining impressions. To illustrate this, a worn but clean and dry shoe was used to step on a piece of glass. Figure 1.3A depicts the resulting impression. The glass had a film of accumulated dirt and residue on it as the exterior surface of glass often does. The shoe lifted that film

10

Footwear Impression Evidence, 2nd Edition

(B )

Figure 1.2 (contin u ed ) (B) A p ie c e of paper w a s step p ed on w ith clean sh o es. N o im p r e ssio n s w ere v is ib le on th e paper b efore p ro cessin g w ith p h y sica l d evelop er. off in the areas of contact leaving a negative impression. The glass was photographed with oblique light and a black background. The impression appears dark, inasmuch as the accumulated film was removed from the glass by the pattern of the shoe allowing the black background to show through. Figure 1.36 also depicts a negative impression which resulted when a shoe stepped on a metal cabinet that contained a heavy coating of accumulated dust and residue. The dust and residue adhered to the portion of the shoe sole that made contact with the cabinet, leaving a light image in those areas. Shoes, including those that are clean and dry, can also leave impressions on carpeting, though many types of carpeting are not suitable for retaining footwear impressions. Some

Awareness, Detection, and Treatment of Footwear Impression Evidence

11

(A|

Figure 1.3

(A) A p ie c e of g la ss w ith a film on it w h ic h w as step p ed o n at a crim e scen e. T h e film , w h ich c o n siste d of a c c u m u la ted dirt and residue, w a s rem o v ed in th e area w h ere th e clean sh o e m ade co n ta ct w ith it, re su ltin g in a n e g a tiv e im p ressio n . W hen p h otograp h ed w ith a dark background, th e im p ressio n ed area sh o w s up dark.

thicker plush pile carpeting, particularly if recently vacuumed, may retain footwear impres­ sions and will reveal limited shape, design, and dimensional information of the footwear. If impressions in carpet are located, they can be photographed with oblique lighting. If the possibility exists that residue was tracked onto the carpet in this area, further treatment with the electrostatic lifting device may also be productive. Although limited in detail, these impressions may furnish information concerning the movement of the subject and the possible location of other footwear impressions. A device known as an Intensified Ultraviolet Viewer (Hammamatsu Corporation, Middlesex, NJ) can be used with a shortwave light source to enable the visual detection and photography of latent impressions made by rubber soled shoes which have tracked across highly reflective polished or waxed surfaces such as a tiled floor. The system uses reflected shortwave ultraviolet light to visualize the otherwise latent impressions. The attachment of a camera to the intensified viewer will provide the means to permanently record those impressions. These examples illustrate that it is very possible for a suspect whose shoes are dry and free of residue or other materials to leave two-dimensional impressions of excellent quality as she or he travels through the crime scene. Impressions made by clean, dry shoes are usually hard to detect. They should be searched for carefully and thoroughly with the proper lighting in areas where the subject may have walked across broken glass, paper, waxed or polished surfaces, or surfaces containing a fine film or residue. Papers which may

Footwear Impression Evidence, 2nd Edition

12

(B)

Figure

1 .3 (contin u ed ) (B) An im p ressio n resu ltin g from a clean sh o e step p in g on a residuecovered cab in et and resu ltin g in a n eg a tiv e im p ressio n .

have been strewn around, which may have dropped on the floor, and those that are otherwise located where the suspect may have stepped, should also be closely examined and may contain indented impressions that can be enhanced. Dry origin residue impressions. When shoes track across a dirty surface, the bottom of the soles will accumulate a coating of residue. If they then track onto a relatively clean surface, the same residue will be deposited in the form of footwear impressions. Impres­ sions of this type are usually visible to some extent; however, in many instances, because of their trace quantity and lack of contrast with the surface, they are often latent. The soles of shoes pick up whatever loose residue and dust may be on the surface they cross. As long as they remain in contact with the same surface, there will probably not be any visible residue impressions left because any residue deposited by the shoe cannot be distinguished from the existing residue on that same surface. When the shoes track across a different and relatively cleaner surface, the shoes deposit that residue onto the cleaner surface. Eventually, if the shoes continue to track across the clean surface, all of the residue will be removed from the surface of the shoe soles. At a crime scene, whenever there are areas that are relatively clean adjacent to areas that are dirty, there is an excellent potential

Awareness, Detection, and Treatment of Footwear Impression Evidence

13

(C)

Figure 1.3

(continu ed ) (C) A p iece of gla ss c o n ta in in g a residue im p ressio n . T h is im p ression sh o w s up ligh t sin c e it is a p o sitiv e residue im p ression and reflects m ore ligh t than th e darker background.

for a transfer of the accumulated residue or dust on shoes from the dirty to be deposited in the form of both visible and latent footwear impressions on the cleaner surface. Some dry residue impressions, because of their lack of contrast with the surface, are difficult to locate and very often go undiscovered under normal lighting. A bright floodlight held low and used to direct an oblique light across the surface, and the electrostatic lifting device, discussed later in this book, are excellent devices for finding and recovering dry residue impressions. Figure 1.4B depicts a strong oblique light source in the darkened room being used to locate a residue impression on the tile floor. A similar dry residue impression on a carpeted surface may not be visible even with oblique light due to the texture of the carpet; however, electrostatic processing of that carpet could potentially lift and reveal that impression. Items such as floors, paper, glass, boxes, and other surfaces that may have been stepped on should always be considered as potential bearers of residue footwear impressions. Figures 1.3C, 1.4, and 1.5 all depict items that were stepped on and which retained dry residue impressions. Figure 1.5A depicts a piece of paper with a partial impression in blood and a very faint impression in residue. An electrostatic lift of the paper enhanced the faint impression and also revealed a second residue impression (Figure 1.5B). The light color of the paper did not provide sufficient contrast to see part of one residue impression and all of the second residue impression. Transferring that impression electrostatically to a

14

Footwear Impression Evidence, 2nd Edition

|A|

Figure

1 .4 (A) A tiJe floor, p ictu red under normaJ indoor overhead lig h tin g , d oes n ot reveal any v isib le footw ear im p ressio n s.

black film provided the needed contrast. Other examples of how the electrostatic lifter can both enhance impressions that contrast poorly with the substrate as well as reveal latent impressions are provided in Chapter 4. VMet origin impressions. Impressions made when a clean shoe sole is wet or damp or the receiving surface is wet or damp constitute another category of impression. Most of these impressions dry before they are found, but must still be considered as impressions of wet origin for the purposes of recovery. When there is rain, heavy dew, or snow on the ground, most of the impressions, particularly at the point of entry, will be wet origin impressions. Many shoe soles retain moisture for a period of time and consequently leave wet origin impressions well inside interior areas. If a wet or damp shoe sole should come in contact with a clean surface, such as a waxed floor, countertop, or desk top, it can leave a watermark or disturbance in the waxed or polished surface. Like dry residue impressions, wet origin impressions of clean shoes are often difficult to see and photograph. Often they are nothing more than disturbances in the wax or film of a polished surface without the accompanying presence of visible transferred residue, they are sometimes latent or can only be seen when the light strikes them from an angle. Wet origin impressions on waxed or polished surfaces can sometimes be enhanced successfully with fingerprint powder. The powder will adhere differently to the contact vs. non-contact areas, resulting in an enhanced impression. The

Awareness, Detection, and Treatment of Footwear Impression Evidence

15

(B)

F ig u r e 1 .4 (contin u ed ) (B) By dark en in g th e room and u sin g a stron g o b liq u e lig h t sou rce h eld c lo se to the ground, several fo o tw ea r im p r e ssio n s b e c o m e v isib le.

enhanced or developed impression can then be photographed and lifted with an adhesive or gelatin lifter of contrasting color. It is not uncommon for this type of impression to be located accidentally while an area is being dusted for fingerprints. A classic example is when a polished bank countertop is stepped on by a vaulting bank robber. The robber s shoe soles either remained damp from the snow or rain outside or had a sole that otherwise created in difference in the contact area and the polished surface of the bank counter. Figure 1.6 depicts an impression of this type that has been enhanced with black fingerprint powder and then lifted with a white adhesive lift material called Handiprint®.*"^ The lift was one of several taken from a bank countertop onto which three subjects had jumped during a bank robbery. The bank countertop was routinely polished with a material that left a slight film on it and which resulted in a detailed but almost latent shoe print. The black fingerprint powder adhered to the non-contact areas of the shoe sole. In this case, both the left and right shoes of each of two apprehended suspects were identified with impressions on the bank counter. The third suspect was not apprehended. Crime scenes often have large, clean, waxed, or polished surfaces or floors which may have been walked or stepped on by suspects having sticky or damp shoes. These areas can contain numerous Rinderprint Company, Martinez, CA.

16

Footwear Impression Evidence, 2nd Edition

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Figure 1.5 (A) A p iece of paper bearing (1) a b lood y fo o tw ea r Im pression and (2) a very ligh t and partial residu e im p ression . footwear impressions of value. In a scenario with surfaces such as these, the crime scene technician might consider processing portions of the floor or other surfaces with a fine fingerprint powder of contrasting color and a feather brush to see if any impressions will develop. Figure 1.6B is a known impression of the shoe that made the impression in Figure 1.6A. Impressions can also occur when the sole is wet and contains visible residue such as mud or a wet residue. Original impressions of wet origin that contain residue or are made on dirty surfaces are sometimes more difficult to lift. In some cases they cannot be lifted successfully. Other impressions, especially those on smooth, non-porous surfaces, may not adhere to the surface and may be very fragile when they dry out. It is often possible to recognize impressions of wet origin based on certain features of the impression itself, such as water stains and smears. If impressions of wet origin on dirty surfaces must be lifted, commercial gelatin lifting materials offer a possible choice. Figure 1.7 shows a wet residue impression lifted with a gelatin lifter. Because this impression is of wet origin, the electro­ static lifting device would not successfully lift it. Other impressions, such as tracked sand or soil across asphalt or tile surfaces, are likely to be of wet origin since the moisture is the reason the material of that type and quantity adhered to the shoe sole. This type of impression, particularly if it is a heavy deposit, may be best recovered by casting with dental stone or with a non-viscous silicone product.

Awareness, Detection, and Treatment of Footwear Impression Evidence

17

(B)

Figure 1.5

(continu ed ) (B) An e le c tr o sta tic Lift of th e sa m e paper n o t o n ly en h a n ced th e resid u e im p ression (2) but revealed a seco n d resid u e im p ressio n n ex t to it (3).

Impressions in other materials. Impressions will result when a shoe tracks through oil, grease, blood, or other similar materials. These types of impressions are usually more visible and easier to detect than the types discussed above, but they can occur as latent impressions as well.

Finding Footwear Impressions at the Scene of the Crime Why Footwear Impressions are Overlooked All crime scenes should be approached with the expectation that they contain footwear impressions. Investigators and crime scene technicians should be aggressive in their search for such impressions. Lack of success in finding footwear impressions at a crime scene is often due to one or more of the following: 1. 2.

Not believing that visible and/or latent footwear impressions will be found at the crime scene and not aggressively looking for them. Incomplete searches of the scene, possibly due in part to the inability to determine the exact points of entry and exit. Searches may also be incomplete because of the lack of proper knowledge of the ways footwear impressions can occur and how they can be found.

18

Footwear Impression Evidence, 2nd Edition

(A|

(B )

Figure 1.6

(A) A la ten t im p ression resu lted from a sh o e step p in g on a bank co u n terto p . T h is im p ression w as en h a n ced by d u stin g w ith black fin gerp rin t pow d er and w as th en lifted w ith a w h ite ad h esiv e liftin g m aterial. (B) A k n o w n im p ressio n ta k en from th e su sp ect's sh o e. N o te th e corresponding w orn areas. A lso n o te so m e of th e a ccid en ta l ch a ra cteristics (arrows).

3.

Arrival at the scene after other persons have trampled over the impression evidence and failure to look for footwear impressions in those areas. Allowing unauthorized persons to walk through the crime scene area. 4. The combination of shoe and surface characteristics not being conducive to the production of footwear impression evidence. 5. The impressions were intentionally destroyed by the subjects. This is an unlikely possibility except in cases involving the clean-up of blood impressions. 6. Weather destroyed exterior impressions. Figure 1.8 is a diagram addressing the likelihood of finding footwear impressions on various surfaces under different circumstances. Its purpose is not to serve as an absolute predictor of how likely it is to find footwear impressions on a particular surface in a specific case. Rather, it is to draw attention to the immense possibilities of finding this form of evidence. As can be seen, the likelihood for an item of footwear to leave either a visible or a detectable latent impression exists in many situations. Those marked "very likely" will occur to some degree in almost every instance. Those marked "likely" will occur very often.

Awareness, Detection, and Treatment of Footwear Impression Evidence

, ?'

19

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Figure 1.7 A

w e t residue im p ression on a porous surface. C h a ra cteristics in th e im p ressio n , su ch as stip p lin g and beading of th e w a ter/resid u e m ix tu re, in d ica te that it is of w e t origin.

Those marked "unlikely" indicate situations in which a footwear impression of value may be possible, but in most instances will not leave a useful impression.

Specific Areas to Check for Footwear Impression Evidence Footwear impressions can be found potentially anywhere in and around the crime scene. Areas where special attention to footwear impression evidence should be given include: The actual point of occurrence of the crime. The point of occurrence is the specific area where the crime was committed. In homicides, rapes, assaults, and other violent crimes, there is often a struggle or extra activity that results in many footwear impressions in the specific area where that crime took place. Impressions may be left in spilled blood, on the victim’s clothing and body resulting from the victim being kicked, or on items knocked to the floor during any struggle. In burglaries, dropped items such as safe insulation, paper, or other debris on the floor as a result of the crime, are often stepped on and retain impressions of the footwear.

Footwear Impression Evidence, 2nd Edition

20

Likelihood oi D etectable Footwear Impressions O ccuning on DIFFERENT TWO-DIMENSIONAL SHOE/SURFACE COMBINATIONS

SURFACE CARPET

Dam p or Wet Shoes

unlikely

Dry Shoe with Shoes Cleon with blood, Dry Shoe grease, Dust or (no dust oil, etc. Residue or residue)

very likely very likely

likely

unlikely

DIRTY FLOOR with acc\imulation of dust, dirt, or residue

likely

RELATIVELY CLEAN, but unwoxed floor

likely

very likely

very likely

unlikely

CLEAN WAXED Tile or W ood Floor

likely

very likely

very likely

likely

WAXED Bonk Counter, Desk Top, etc.

likely

very likely

very likely

likely

GLASS

very likely

very likely

very likely

likely

KICKED IN DOOR

very ükely

very likely

very likely

likely

PAPFP

very likely

very likely

very likely

likely

CARDBOARD, etc.

unlikely unlikely

Figure 1.8 T h e lik e lih o o d of tw o-d im en sion aJ footw ear im p ressio n s of valu e for e x a m in a tio n purposes being left on variou s su rfaces is greater than you m ig h t ex p ect. T h o se c o m b in a tio n s m arked "very likely" reflect an a lm o st certain occu rren ce o f a fo o tw ea r im p ressio n . T h o se m arked "likely" reflect a reasonable ch a n ce of a fo o tw ea r im p ressio n . T h o se m arked "unlikely" reflect a situ a tio n w h ere it is n o t lik ely , b ut still p o ssib le to h a v e a fo o tw ea r im p ression occur. The point of entry. The point of entry is the location where the subject entered an interior area. If a window has been pried-open or broken, or a door has been kicked in, or a similarly obvious point of forced entry is found, the area where the subject would have walked before and after they entered the scene can be specifically defined. Forced entries, because of the unnatural way in which the subject entered, and because of the greater likelihood of stepping on objects, debris, or broken glass, usually provide a greater chance for finding footwear impressions than crime scenes where the point of entry was a common one, such as the front door or a public entrance. The search for impressions should also include the adjacent exterior surfaces, such as flower beds, back porches, or other areas immediately outside that point of entry. The path through the crime area. Depending on the nature of the crime and whether the points of entry, occurrence, and exit can be determined, the path the subject took through the crime scene may or may not be apparent. Anywhere the path is apparent

Awareness, Detection, and Treatment of Footwear Impression Evidence

21

should be thoroughly searched with oblique light, particularly if that pathway travels through dusty or dirty surfaces, such as an unfinished basement floor or a dusty porch. The point of exit and other exterior areas. Exit routes from an interior crime scene may be harder to determine since the subject will normally exit through a doorway and over the common walkways. Impressions in soft exterior ground surfaces that lead away from the general scene may indicate the direction in which the subject fled. Crime scenes adjacent to or surrounded by soft ground surfaces should be immediately sealed off and carefully searched. The location of footwear impressions in exterior areas left by the suspect while fleeing the scene may also result in the discovery of additional evidence, such as discarded weapons and tire tread impressions. In addition, in rapes, stalkings, and similar planned crimes, often the subject will hide outside and observe the area prior to committing the crime. It is therefore not uncommon to find footwear impressions just outside a crime scene near trees, bushes, or other obstruc­ tions behind which the subject hid. Exterior surfaces that are either snow-covered or that consist of soft soil or sand, if properly preserved and searched, can provide extensive footwear evidence. Near other footwear impressions. When any footwear impression is located, it provides an important clue to the possible location of other footwear impressions.

General Crime Scene Procedures In order to help assure better success in the search for footwear impression evidence, the following suggestions are made for consideration in the current crime scene procedure: Seal the scene. Do no allow anyone, including unnecessary law enforcement personnel, into the general crime scene area, except as necessary such as to tend to victims or to secure the area. This should include broad exterior areas where the subject may have left impressions either before or after the crime. When the actual crime scene search begins, only those conducting that search should walk through the scene. 2 . If it is the scene of a homicide, remember that valuable impressions are often located around and beneath the victim's body. These can be destroyed easily by paramedics or medical examiners if not protected. 3. Prior to the crime scene search, determine what crime has taken place, the point of occurrence and the points of entry or exit, if possible, and whatever other details of the crime that are known. Based on this knowledge, try to reconstruct what occurred during the crime. Consider what physical conditions were present both inside and outside the scene that were particularly good for retaining footwear impressions. Look for the type of footwear impression evidence that the conditions and surfaces would warrant. If weather is a factor, first tend to those impressions that could deteriorate or be destroyed. 4. Be especially aware of those impressions that, due to their partial or latent nature, may be harder to detect. Realize that partial impressions and other impressions that might initially look to be of limited value are as easily examined and as potentially identifiable as full impressions. 5. Photograph and recover the original footwear impression evidence. If the original evidence cannot be removed and preserved, use the necessary casting, lifting, and enhancement methods to preserve and recover the impression. 1.

22

Footwear Impression Evidence, 2nd Edition

Methods of Searching Search for impressions in one small area or room at one time. A methodical visual search with existing light should be made first. Existing light will allow for detection of the obvious and most visible footwear impressions, such as those in blood, grease, or other visible residue. At this time, the general layout of the area including obvious paths the suspect may have taken and areas to avoid walking over during the search can be assessed. To assist in locating footwear impressions that are not easily detected in normal lighting, the area being searched should be darkened, whenever possible. A bright oblique light source held just off of and parallel to the ground, as shown in Figure 1.4A, should be used to search for those residue or dust impressions that are not visible in normal room light. A portable halogen flood light is most effective; however, a high intensity flashlight will also work sufficiently provided the room can be darkened totally. The oblique light works best for detecting impressions on smooth surfaces like tile or wood flooring. Impressions on carpeting or other rough or porous surfaces may still not be visible, even with the oblique light. The electrostatic lifting device can also be used to search specific areas for dry residue impressions. Very often, investigators neglect to search certain areas of the crime scene because they have been walked over by other investigators, paramedics, or other individuals. It should be emphasized that although the general area that contains the suspect's impressions may have been walked over many times, the impressions themselves may not necessarily have been tracked over. Further, the chances of all of the subject’s impressions being completely obliterated by crime scene personnel is unlikely. Even if an impression was tracked over, part of that impression would probably still be untouched and would potentially be just as valuable as any other partial impression.

Hypothetical Crime Scene Figure 1.9 is a diagram of a hypothetical crime scene. It provides a few examples of how a person could leave footwear impressions at various locations and in various ways. Although it is unlikely that all of the impressions in this example would be left at a single scene, it is not unlikely that several types could be found at a single scene. In the example shown in Figure 1.9, the first impressions left (1) were those retained in the soil behind some shrubbery. Criminals commonly stalk or observe the scene or the victim prior to the crime, and therefore impressions in soft exterior surfaces where the subject stood, walked, or hid can often be found. Err route to the point of entry, the subject walked across wet, dew-covered grass. The subject then broke into the house through a glass window. As the subject stepped through the window onto a desk, a footwear impression was left on a piece of the broken glass from the window (2) by one of the damp shoes and also on the desktop itself (3) which has a waxed surface. No impressions were left on the carpet in that room by the damp but clean shoes. As the subject walked through the next room, which has a dry but dirty floor, the shoes accumulated the dry residue. The subject then kicked open a locked door (4) and left a dry residue impression on it. Further steps into the next room across the clean tile floor left additional residue footwear impressions for the first few steps (5), until the shoes no longer contained residue. These impressions would probably only be detected with a strong oblique light or the electrostatic lifting device. The fact that one room is dirty and the next clean, combined with the door as the known point of entry, should

Awareness, Detection, and Treatment of Footwear Impression Evidence

8

6

OIL STAm

HemHsMe V(CT«»

8 Non-detectable Footwear Impression g Detectable J Footwear impression

i^APER

8

23

% %

ÖLÖOO

s

8

€»orage cmmâmm

. ..... T ile F lo o r .. ¡. P: .-i

'A k

1

AM»

9

Impressions in Soil

2 Damp Shoes Leave Impressions on Glass

3 4

and Waxed Desktop

I

Dry Residue Impression on Kicked-in Door

5

Residue Impressions on Floor

6

Blood Impressions on Tile Floor and Part of Paper Folder Dropped by Victim

I Impressions In Soil Where Subject Hid

7 Trace Element Impression from Clean Part of Shoe on Paper Folder 8 Grease-Oil Stain on Concrete 9

K IC K E D D O O R

Impressions in Flower Bed

CAHPETEn

F1.00R OD



c:=o

Damp Impression on Waxed Desktop^ Impression on Broken Glass

Figure 1.9

A hypotheticaJ crim e sc e n e illu str a te s so m e of th e m a n y w a y s in w h ich fo o tw ea r im p ressio n s can occu r at a crim e scen e.

suggest to the crime scene technician that footwear impression evidence may exist on the cleaner floor. Next, the subject moved through the carpeted room with clean shoes. On this partic­ ular carpeting, no permanent impressions of value were left, although the indentations show the direction of the perpetrator. As the subject moved part way into the kitchen onto the clean tile floor, no impressions were left initially, until the homicide was committed. Then during the commission of the crime, some papers were knocked to the floor and some blood from the victim reached the floor. The left shoe stepped entirely in a pool of blood and left a series of tracked blood impressions over the next few steps (6). The toe

24

Footwear Impression Evidence, 2nd Edition

of the right shoe stepped only partially in the blood. It then left a partial blood impression on the paper (7) and subsequently tracked several partial blood impressions across the tile floor. The position of the toe area of the impression on the paper indicates that the remaining area of the shoe also stepped on the paper. The paper is therefore a candidate for chemical processing to develop the remaining latent impression on the paper. Upon entering the garage, the subject stepped in an oil stain with one shoe and subsequently tracked impressions in oil (8). After the subject left the garage, some additional impressions were made outside in the soft flower bed, and these indicate the direction in which the subject fled (9).

General Treatment of Impressions The success achieved in the recovery portion is of extreme importance. If impression evidence is not recovered properly, important details in the impressions will be lost, and the examination results may be affected. There are many techniques, materials, and pieces of equipment that are used to recover footwear impressions from the crime scene. These are covered in Chapters 2 through 5. Because of the innumerable combinations of impression forms and substrates, no one technique or enhancement process will suffice to recover all or even a majority of the impressions. It is therefore essential that one be familiar with and routinely use many methods and materials to maximize the success of recovery and the subsequent usage of this evidence. Inadequate recovery for impression evidence is a major reason for limited results in subsequent examinations. In a recent study in Finland (Majamaa, 1995), statistics were presented on the success rates of different forms of footwear evidence. Shoeprints recovered as originals comprised 28.6% (87.5% of these were either on glass or paper); as gelatin lifts, 52.8%; as photo­ graphed impressions, 10.8%; and as casts, 7.9%. The study reflected that the best exami­ nation results were obtained if the shoeprints submitted to the laboratory consisted of the original evidence, in which case, definite identifications were reached in 19.7% of the cases and probable conclusions in 20.2% of the cases. Of those impressions submitted on gelatin lifts, 16.0% of the cases led to an identification and 15.8% to a probable conclusion. Any use of the electrostatic lifter was not included. Photographed impressions and cast impres­ sions resulted in less identifications. In another study (Baldwin et al., 1994), positive identifications in footwear impression cases overall were made in 24% of the cases, with some form of corroboration in an additional 56% of the cases. Out of those identifications, original evidence, in the form of paper, glass, and other stepped on objects, accounted for the majority of identifications, with lifts and photographs accounting for most of the remaining identifications. It should be noted that in both studies, the surveys involved jurisdictions whose cases predominately consisted of indoor burglary crime scenes and far fewer violent crimes than are found, for instance, in casework in the U.S. Different case categories, i.e., homicide and rapes vs. burglaries, will naturally include footwear impressions in different materials, i.e., blood vs. residue, and on a greater variety of substrates, including a much higher percentage of three-dimensional impressions, and therefore an increased percentage of casts. It has been my experience that dental stone casts also yield a significant percentage of positive and probable identifications. In addition, predominant or favored methods of

Awareness, Detection, and Treatment of Footwear Impression Evidence

25

recovery in one laboratory or country may not be the same as another. Further, policies in some countries or localities restrict the seizure of original evidence, such as removing doors, parts of flooring, etc. This policy is very unfortunate, particularly if it involves a violent crime, where that restriction may prevent the examination of the original evidence. It is noted that both studies are consistent in the fact that, regardless of the type of crime, original evidence yields better results. The succeeding chapters on photography, casting, lifting, and enhancement will pro­ vide additional information regarding the procedures, methods, and materials for those techniques. Once detected, general guidelines for the treatment and recovery of footwear impressions should be handled as follows: Take General Crime Scene Photographs. They provide a recording of the original appear­ ance and location of the impression. Take "Examination Quality" Photographs With a Scale. These are close-up photographs which record the detail necessary to permit a scientific comparison with the suspect's shoes. Make Notes and Crime Scene Sketches. They note the exact whereabouts, and conditions and circumstances surrounding the footwear impressions and coordinate the pho­ tographs, casts, and lifts with the scene. Remove the Impressioned Item From the Scene. All original impressions should be removed from the scene, if possible. These would include pieces of paper, glass, etc. In addition, in more serious crimes, to enable better processing of the evidence, original impressions that are more difficult to remove should also be preserved and transmitted to the laboratory. This should be considered, even if it means cutting out carpeting, flooring, etc. If the impressioned item cannot be physically removed from the scene, then utilize techniques such as casting, lifting, and enhancement to recover the maximum amount of detail. Note: Never cover an impression with tape or plastic. This will only serve to obliterate it or make subsequent enhancement impossible. Figure 1.10 is an outline that provides general instructions for the treatment of foot­ wear impressions at a crime scene. Take General Crime Scene Photographs and Notes Take Examination Q u a lit^h o to g ra p h s of Impressions

__________ I 3-Dimensional Impressions

1

r

RETRIEVE and PRESERVE ALL ORIGINAL IMPRESSION EVIDENCE wnich CAN be REMOVED from the CRIME SCENE

LABORATORY

TWO-DIMENSIONAL IMPRESSIONS which CANNOT i oe REMOVED from the CRIME SCENE

j

DEPENDING on MAKEUP of IMPRESSION and the SURFACE IT IS ON— USE APPROPRIATE TECHNIQUES such as ELECTROSTATIC LIFTING . GELATIN LIFTING. POWDERING. ENHANCEMENT and REPHOTOGRAPH

Figure 1 .10 scen es.

I I I |

G eneral in str u c tio n s for th e tre a tm e n t of fo o tw ea r im p ressio n e v id e n c e at crim e

Photography of Footwear Impressions

2

Photography at crime scenes is an unsurpassed means of illustrating items of evidence, their relationship to each other, and their physical surroundings. Photography, if conducted properly, accomplishes this with great efficiency and detail. In addition to providing a pictorial documentation of the crime scene, photographs assist in the overall investigation. They are often used to support and verify testimony of witnesses and to assist in the evaluation of evidence. In some cases, photographs may be a critical factor in determining the guilt or innocence of a suspect. There are two separate categories of photography that are routinely used to record information at a crime scene — general crime scene photography and examination quality photography. General crime scene photographs are normally taken from two or three distances, providing a zoom-in effect on a particular area or object. They include (1) long range photographs that show the overall scene, (2) mid-range photographs that show a closer view of a certain area, and (3) close range photographs that concentrate on a particular area or object as it relates to its immediate surroundings. (Figure 2.1 A-C) The second category of photography at crime scenes involves the taking of examination quality photographs of specific evidence such as fingerprints, toolmarks, bitemarks, tire impres­ sions, and shoe prints. Examination quality photographs are those taken from directly over top of and sufficiently close to the object, to fill the photographic frame with the area or object being photographed and to capture the maximum amount of detail. This method allows the use of these photographs for later analysis or examination (Figure 2.1 D).

General Crime Scene Photography General crime scene photography can present a broad range of photographic problems. The scenes and various items that need to be photographed vary immensely from one crime scene to another. In this chapter, only the aspects of general crime scene photography as they relate to footwear impression evidence will be addressed. Additional information concerning general crime scene photography or photography in general should be obtained from other sources, as needed.

27

Footwear Impression Evidence, 2nd Edition

28

i p r ; j : -' .A

**

%1ÿ

Figure 2.1

,,

' -i '

^x.::^ >iMi^

~

-

''^^' '''-X .' f ^

(A-D) R elatin g th e fo o tw ea r im p ressio n to th e sc e n e is best d on e by p la cin g m arkers or num bers n ext to th e im p ressio n . T h e long-range, m ed iu m -ran ge, and cJ o s e -range general crim e sc e n e photographs (A through C) p rovide a "zoom-in" effect on th e footw ear im p ression . A series of ex a m in a tio n q u a lity photographs, o n e of w h ich is d ep icted in D, c o m p le te s th e photographic d o cu m e n ta tio n of th at e v id e n c e and p rovid es h ig h ly d etailed , q u a lity p hotographs su ita b le for a sc ie n tific com p arison w ith a k n ow n sh o e of a su sp ect. T h e particular photograph d ep icted in D w as tak en u sin g th e natural o b liq u e lig h t of th e su n . AdditionaJ p h otograp h s w ith th at lig h t b lock ed o u t and u sin g o b liq u e lig h t from a flash sh o u ld also be tak en (see Figure 2 .1 5C).

Photography of Footwear Impressions

Figure 2.1

29

(continued)

Camera and Film Choices for General Crime Scene Photography The camera used for general crime scene photographs should be capable of conveniently taking the full range of distant, medium, and close range photographs. A 35-mm or 2 1/4in. negative format camera with a zoom lens is suitable for this. Color films having an ISO

30

Footwear Impression Evidence, 2nd Edition

of 400 are usually the preferred film choice for general crime scene photography because they are more flexible under a variety of lighting conditions. Photography in very low light situations may necessitate the use of ISO 800 or 1000 film.

Relating the Footwear Impression to the Scene General scene photographs, accompanied by logs or notes, should document and describe the recovery, location, and orientation of the impressions. Each impression should be numbered, labeled, or otherwise described so the notes, photographs, lifts, and casts can be linked to one another. The notes should include descriptions of impressions (i.e., a muddy impression on tile floor), their direction (i.e., exiting kitchen, heading up stairway, etc.), and weather and substrate conditions (dew on grass, old snow on asphalt, concrete garage floor on rainy day, etc.). One easy method for relating the noted footwear impressions to the general crime scene photographs, crime scene sketches, lifts, casts, and examination quality photographs is to place a numbered cone or marker next to each impression or piece of evidence. That same number can then be used as a reference for all items of evidence relating to that impression. Figure 2.1 shows an example of how this simple technique can be used to make a permanent and accurate record of the footwear impressions at the crime scene. The long range, medium range, and close range photographs (Figure 2.1A-C) provide a "zoom-in" effect that documents precisely which footwear impressions were found at what locations. Then several examination quality photographs, like the example in Figure 2 .ID, with the corresponding number on the label in each photograph, are taken and provide the greater detail necessary for use in the examination of that impression. This method will not only assist the crime scene officer's documentation of the crime scene, but will also make easier the recollection of the circumstances surrounding the recovery of the impressions. Coordinating the photographs, crime scene sketches, and notes with one another in this manner will enable easier reconstruction of the crime scene at a much later date. It will allow anyone to view a particular impression in any general crime scene photograph and refer to that same impression in the crime scene sketch and notes, as well as in the examination quality photographs. If general crime scene photo­ graphs have been taken without labeling or numbering the impressions, it may be difficult or impossible for an examiner to recall months or years later where a cast or lift of an impression originated from.

Examination Quality Photography Examination quality photographs, sometimes called evidence photographs, are those taken in a manner that best records the maximum amount of detail in the impression. That detail is necessary so that these photographs can be used in scientific comparisons with known shoes. They are clearly different than the general scene photographs, which are taken only to show the location and general features of the impressions and which therefore do not capture very much detail within the impression itself. To ensure that examination quality photographs of impressions provide the footwear examiner with the maximum amount of detail and accuracy, they must be taken in a certain

Photography of Footwear Impressions

31

Figure 2 .2

T hree of th e m o st c o m m o n ly used cam eras for both crim e sc e n e and e x a m in a tio n q u ality photographs are (1) th e 4 x 5-in . cam era, (2) th e 2 1/4-in . cam era, w h ich u se s 120 roll film , and (3) th e 3 5 -m m cam era, w h ic h u ses 3 5 -m m roll film .

prescribed way. Consideration must also be given to the type of camera, film, lighting, and other factors, as discussed below.

Selecting the Right Camera There are three different categories of cameras that are commonly used for examination quality photographs. Those cameras hold the 4 x 5-in., the 2 1/4-in., and the 35-mm negative sizes (Figure 2.2). Before selecting the type of camera to be used for examination quality photographs, it should be understood that the original negatives will have to be enlarged from 2 to 20 or more times, depending on the size of the impression, the negative size, and the area the impression occupies on the negative. Figure 2.3 illustrates the relative size of the 35-mm, 2 1/4-in., and 4 x 5-in. negatives compared with the actual size of the footwear impression. Referring to the example in the illustration, it is easy to visualize how many times each negative would have to be enlarged before it would reach the natural size of the footwear impression. The 35-mm negative would have to be enlarged 10 times, the 2 1/4-in. negative would have to be enlarged 5 1/2 times and the 4 x 5-in. negative would have to be enlarged 2 1/2 times in order to bring the impression up to its real-life natural size. These calculations presume that the negative areas were fully used, meaning that the footwear impression images filled most of the space on the negatives. If the impression’s image represented a smaller portion of the negative, the negative would have to be enlarged even more to produce a life size print. Cameras having larger negative sizes are therefore better suited for examination quality photographs. Unfortunately, cameras having large negative formats are not used by as

32

Footwear Impression Evidence, 2nd Edition

1

Î

?

1

f

?

1

h

?

V

35 MM

V

2 1 / 4 INCH

4x5 INCH Figure 2.3

R ela tio n sh ip s of th e im age siz e on 4 x 5 -in ., 2 1/4 -in ., and 3 5 -m m n eg a tiv es to th e natural siz e of th e im p ressio n . B ecau se th e im age siz e is sm a ller on th e 3 5 -m m n egative, it w ill require greater en la rg em en t than a 2 1/4-in . or 4 x 5-in . n eg a tiv e to m a k e a n atu ral-size print.

many crime scene photographers as are smaller cameras, due to cost, convenience, expe­ rience, and persona] choice. The 4 X 5-in. camera is the largest negative format camera that is normally used at a crime scene. This camera requires 4 x 5-in. single-sheet film. The size and weight of this camera make it more cumbersome, and a photographer having considerable experience with this type of camera is usually required in order to take full advantage of its capabilities. The amount of photographic information recordable on a 4 x 5-in. negative camera exceeds that of the 2 1/4-in. and 35-mm cameras because of the larger negative size. The 2 1/4-in. negative format cameras have replaced many of the 4 x 5-in. cameras of crime scene photographers. They still have a relatively large negative format, but are more versatile. In addition, they use roll film instead of hand-loaded sheet film. Some 2 1/4-in. cameras (Figure 2.2) operate with through-the-lens focusing and metering in the same manner as a 35-mm camera. The 35-mm camera is the camera most commonly used at crime scenes for several reasons. It is less expensive than the 4 X 5-in. and 2 1/4-in. format cameras. It is easier to train personnel to use, especially since many have 35-mm cameras of their own. It is used by many investigators who take crime scene photographs because their departments lack a designated crime scene photographer. The negative size of the 35-mm camera is much smaller than that of the 2 1/4-in. and 4 X 5-in. cameras. Even if the image size of a footwear impression fills the majority of the negative, the negative will have to be enlarged 10 or more times its size, before a natural size photographic print of a full footwear impression can be made. This requires the photographer using a 35-mm camera to take as perfect a

Photography of Footwear Impressions

33

picture as possible and leaves virtually no room for error. Slight focus problems, the use of poor film, or any slight movement of the camera will interfere with the detail in the image and will become more apparent when the enlarged, natural-size prints are made. It should be emphasized that in order to take examination quality photographs with a 35mm camera and obtain quality evidence photographs that capture the minute detail which is present in the impressions, the instructions provided in this chapter should be followed. The 35-mm camera for this type of photography should not be the fixed-lens variety which is restricted to built-in auto-flash and auto-focus features. The 35-mm camera used for evidence photography must have a removable lens and must permit the option of manual focusing. In addition, the flash must be removable and usable on a long 6-ft flash extension cord attached to and synchronized with the camera. The camera can be equipped with either a zoom lens in the 35- to 80-mm range or with a macro lens. A camera equipped with a zoom lens of this range and mounted on a tripod will normally be able to frame and focus on a full size shoe impression from a height of approximately 3 ft. The zoom feature can be adjusted to fill the frame with the impression and ruler. One disadvantage of most zoom lenses is that they cannot be used for extreme close up photography. The macro lens will enable close-up photography capabilities, if needed, but its height above the impression must be adjusted by moving the tripod to properly frame the impression and ruler. Figure 2.4A shows a properly equipped, manual-focus 35-mm camera mounted on a tripod. This camera is equipped with a 50-mm macro lens, a focus adapter, a cable shutter release, an electronic flash, and a 6-ft flash extension cord. It is loaded with a fine-grained ISO 100 color film. Equipped in this manner and properly used, the 35-mm camera can be used to take examination quality photographs. Cameras that have a smaller negative format, such as the 110-mm format cameras, are definitely not suited or intended for this type of photography.

Digital Cameras Digital cameras are becoming increasingly common and useful for many purposes; how­ ever, they still are not a realistic replacement for the traditional camera and film when taking detailed examination quality photographs. Currently, digital cameras of the more affordable variety operate and are equipped like the point and shoot cameras inasmuch as they do not have interchangeable lenses, removable flash units, or manual focus capa­ bilities. Digital cameras that do have these capabilities are still very expensive. The digital chip in the camera will determine the resolution in place of the film. Even the best and most expensive cameras currently sold are only coming close to the resolution of what an average 35-mm camera can produce. In addition, to support the digital camera, a computer with the necessary supporting software, plus a quality printer, will be necessary to produce the image. To enlarge the image to an accurate natural size, which is necessary for exam­ ination, either a computer scaling program with a large printing unit, or the transfer of the image to the conventional film format are required. As years pass, the digital camera will improve; however, currently, the conventional camera and film are still superior for examination quality photography and are far less expensive.

Footwear Impression Evidence, 2nd Edition

34

(A)

F ig u r e 2 .4 (A) A 3 5 -m m cam era properly set up w ith a th in , flat scaJe to photograph an im p ression on a tw o -d im e n sio n a l surface. N o te th e u se of th e in verted tripod and th e 6 ft flash ex te n sio n cord.

Choosing the Proper Film In the past, the use of most color films was not recommended for examination quality photographs, especially for those photographs intended to show fine detail after consid­ erable enlargement. Today s film technology has improved to the extent that a quality color film, having an ISO of 400 or less, is adequate for examination quality photographs. With some impressions, such as contusion impressions on a body, impressions in blood, or impressions on other materials that might be different in color from their background, but similar in tonal qualities, color film may enable the footwear examiner to better interpret the information present in those impressions. Black-and-white film has some advantages over color film that also make it well suited for most examination quality photography. It can be processed for its finest grain structure and its contrast can be enhanced or reduced when making prints. In addition, filters can be used on occasion when photographing impressions to accent the contrast of the impres­ sion while diminishing a colored background. Films are constantly being improved. The major film companies have law enforcement representatives who can be consulted regard­ ing their best and current films for this type of photography. Instant films, those that provide an instant print at the scene, should not be used for examination quality photographs. Their resolution is not as good as the better conventional

Photography of Footwear Impressions

35

film choices and they usually do not produce a negative. Slide film is not recommended for impression photography due to the additional steps necessary in making natural size prints for examination.

Choosing and Using a Scale The importance of using a scale. When enlargements are made for examination purposes, they can be enlarged to a natural size only by referring to that scale. The term natural size, as used here, means that the photographic enlargement is sized so that 1 in. (or mm) on the scale in the enlarged photograph equals one actual inch or millimeter. This should not be confused with the photographic term of ''one to one'' (1:1). In a true 1:1 photograph, the size of the image on the negative is the actual life size of the object being photographed. Thus, a 1:1 photographic contact print will always be natural size, but a natural-size print is not always from a 1:1 photograph. Although this may sound trivial, it is mentioned here for two reasons. First, in the case of footwear impressions, which usually are in the 10 to 13 in. range, it would be necessary to have a camera with a negative of that size before it would be possible to take a true 1:1 photograph. Since it is not practical to have cameras with that negative format size at a crime scene, the use of a ruler or other acceptable scale in the photograph is absolutely essential so the photograph can be accurately enlarged to a natural size. Second, the tendency by some persons to use the terms " T T and "natural size" interchangeably make it appropriate here to restate the difference between them. One of the most common mistakes made in taking examination quality photographs is either not using a scale or using an improper scale. A scale should always be used when making examination quality photographs of evidence so that a reference of size is present and it should be used in every examination quality photograph taken. Many years ago, it was reported that a judge in one case did not accept photographs of footwear impressions that depicted a ruler next to the impression. This rationale was that only photographs of the impressions, as they naturally appeared and were first seen at the crime scene, should be used in court. Unfortunately, as an over-reaction to this alleged, but not confirmed, single incident, some individuals have instructed their students to alternately take photographs first without, and then with, a scale. Several of the older articles on the topic of footwear impression evidence also recommend that only every other photograph of an impression should contain a scale. Although in theory, two subsequent photographs of equal quality, one having a scale and the other not, could be taken by an expert photographer, this rarely proves to be the case in real-life practice at crime scenes. In addition, this requirement would automatically double the number of photographs that otherwise would have to be taken. Even though there is no known problem admitting photographs with a scale into evidence, for some unknown reason, there are actually persons today who still teach this counter-productive method. Any examination quality photograph, without a scale, is of limited value to an examiner. Always use a scale in every examination quality photograph! Should the unlikely instance ever occur where a court requires photographs without the scale in them, then photographic prints with the scale cropped out can be used. Also, remember that the close range general crime scene photographs, which do not contain a scale, can also be used in court as a record of where that impression was found and how it appeared when first discovered. The best type of scale. Many items have been placed next to footwear impressions for use as a scale. These items, which include countless varieties of rulers, coins, pens, pencils.

36

Footwear Impression Evidence, 2nd Edition

business cards, keys, flashlights, and shoes, were positioned beside the impression with the hope that they could be used as a reference of size to enlarge the impressions to their natural size. Frequently the question arises "What is the best scale to use when photographing impression evidence?" Before answering that question, it is necessary to understand what qualities are needed in a scale, why they are needed, and the degree of accuracy that different scales can provide. Based on years of experience in examining, photographing, and working with photo­ graphic enlargements of impression evidence, certain qualities of scales have been recog­ nized as essential. These qualities are best assembled in the form of a linear scale such as a ruler. Length of the scale. The scale used should ideally extend the full length of the impression. It should be a minimum of 6 in. (150 mm) long. The scale should be positioned evenly and on the same plane as the impressed surface. This is sometimes more difficult with a very short scale. The additional length is also important when natural-sized photographic prints are being made. It is far easier to be accurate when making a natural-sized photo­ graphic print using the reference marks on a scale 6 to 12 in. in length than it is to use reference marks on a scale which is only 1 or 2 in. long. Realizing that it is sometimes difficult in a darkroom to line up the scales precisely, consider this: If the person making the photographic enlargement is 1/32 in. off when using a 1-in. scale, then for a 12-in. footwear impression, the total error will be 12 times that amount, or 3/8 in. If a 12-in. scale is used instead, and the person making the enlargement is 1/32 in. off for the full 12in. scale, the total error would be only that same 1/32 in. Using the full 12-in. scale in the darkroom simply makes it much easier to be accurate. Of course, it is possible to print accurate enlargements with the smaller scale, but it is far more difficult and more prone to error. Aids in checking perspective. The ruler should be level and parallel to the impression and the film plane, or perspective and scaling problems can occur. Photographs of impres­ sions that are positioned directly over the impression and taken in the correct manner should not have any significant perspective problems. Since the examiner is frequently not the photographer, something present in the photograph, which will confirm that the perspective is correct, is often valuable. Whereas pronounced perspective problems are usually very apparent in a photographed impression, minor perspective problems are harder to identify without aids. In the case of a ruler, certain aids, if present, can provide assistance in detecting and/or correcting perspective problems. One such aid is a right-angled ruler. A right-angled ruler is a better instrument for the determination and possible correction of any perspective problems than a straight ruler. It is also particularly valuable for those two-dimensional impressions that seem to disappear when the camera is positioned directly over the impression, yet seem to show up well when viewed and photographed at an angle. In those cases, as a last resort only, it might be necessary to intentionally take the photograph out of perspective and then attempt to correct that perspective later on. If a right-angled ruler is available, it should be used whenever the ruler can be placed evenly and on the same plane as the questioned impression. This would include most two-dimensional impressions and some threedimensional impressions. Precautions should be taken when using a right-angled ruler to assure that the ruler is level, does not sag, and does not cross over the top of the impression.

Photography of Footwear Impressions

37

An angled or tilted ruler could make the photographed impression appear to be out of perspective. Another aid that provides assistance in detecting and/or correcting perspective prob­ lems is a circle. Circles that are viewed straight-on will appear round. If they are viewed at an angle, they will appear elliptical. Thus, any ruler, straight or right-angled, with circles on it, can offer some additional assistance in both detecting and correcting perspective. Surface qualities of scales. Whether a straight or right-angled ruler, the scale should have a nonreflective surface with contrasting numerals and markings. This will make them more distinct and readable under the variety of lighting and exposures that will be encoun­ tered. The contrasting scale should be finely divided into increments of 1/32 in. or into millimeters. A variety of rulers is available in nonreflective colors, i.e., black numerals on a white background, black numerals on a gray background, white on gray, and so forth. The nonreflective surface is necessary to prevent unwanted reflections of light into the lens of the camera, which in turn could interfere with both the overall exposure of the impression and the legibility of the scale in that area. One way to place a nonreflective matte surface on any reflective ruler is to spray the ruler with a photographic matte spray. This will dull the reflective surface and can trans­ form a highly reflective metal or plastic ruler into a usable nonreflective scale. Physical characteristics of scales. The ruler should be both flat and thin. The thickness of the ruler should be ideally no greater than 1/32 in. thick. Flatness is needed for several reasons. The ruler must be placed on the same plane as an impression. A thick ruler simply cannot be placed on the same plane as an impression on a hard surface such as a tile floor. A 1/4-in thick ruler next to a bloody footwear impression on a tile floor, when enlarged so that 12 in. on the ruler equals 12 in. on the photographic print, will have an error factor of approximately 1/8 in. per 12 in. With a 1/32-in. thick flat ruler, the error is negligible. In a three-dimensional impression in sand, soil, or snow, where the ruler must be set into the adjacent surface so that it is on the same plane as the bottom of the impression, the thickness is not a factor since the ruler can be set into the ground until the top surface bearing the scale is on the proper plane. Figure 2.4B depicts three identical rulers that were placed on different planes at a distance of approximately 1/4 in. between each level. The 80-mm mark of each scale was lined up evenly between each ruler and was photographed from above (Figure 2.4C). The rulers appear to be different sizes, even though they are identical. The ruler closest to the camera appears larger and the ruler farthest away appears smaller. Note the differences in the scale markings. This demonstrates the potential problem of photographing an impres­ sion with a ruler that is not on the same plane. In the example, if the ruler closest to the camera is the scale and the ruler farthest away from the camera is the impression, the impression would be misrepresented as being smaller than it actually is. The impression can only be enlarged to its natural size accurately if the scale is on the same plane as the impression. The ruler must also be rigid in order to assure that it is not sagging or twisting. It is also important that the ruler be totally flat as opposed to a beveled or sculptured ruler. The flatness assures uniformity of the scale markings and also prevents a misreading of the ruler during the enlargement process as in cases where the scale markings on the ruler vary from high spots to low spots. Rulers that have the scale angled on their beveled or sculptured edges are not desirable.

38

Footwear Impression Evidence, 2nd Edition

(B )

Figure 2 .4

(contin u ed ) (B) T h ree rulers, here placed on differen t planes, sim u la te the problem th a t couJd be en co u n tered w h en p h otograp h in g three-d im en sion aJ im p ressio n s w h ere th e scale is on a different plane th an th e im p ressio n and th e sca le is later u sed as a reference to enlarge that photograph to an accu rate natural size.

Bureau scale. For many years, every time I examined photographs from a crime scene or those photographs taken in the laboratory, a different scale was used. Some of these scales were satisfactory, but others were not. In an effort to provide a scale that met the requirements for examination quality photography at the crime scene, forensic photogra­ phy in the laboratory, as well as photogrametry, four individuals in the FBI Laboratory' jointly designed an L-shaped ruler. The ruler is very thin, but rigid, and is non-reflective. One side is white and the other side black, both containing finely divided increments of 1 mm. Although the ruler has a metric scale, its length approximates 13 in. and its width approximates 7 in. It is thin enough to cut with scissors, should its larger size not be needed or should its L-shape interfere with the positioning of the ruler. A shorter companion ruler, approximately 6 in. in length, was also produced. The white sides of both rulers are used for most crime scene and laboratory photography. The black sides are used for longer exposures, such as those taken of the black electrostatic lifters under special lighting conditions. Both sides of the rulers also include three circles, which assist in detecting any perspective problems. The ruler is non-reactive to ultraviolet or infrared light, allowing for its use in the full spectrum. The ruler, or others that are very similar to it, has been used extensively since its introduction. Scale comparisons. Figures 2.5 and 2.6 show a comparison of several scales and the advantages and disadvantages of each. The choices listed represent those that have been ' William ]. Bodziak, Gerald Richards, David Lowe, and Danny Reen.

Photography of Footwear Impressions

. .■i

,,,

39

.................. . ... .

§e.

'

??i

-

'

'is

, , ;

i--;.'.'"’« .-w

i

,1

(C)

Figure 2 .4

(continued) (C) T h e sa m e th ree rulers as in Figure 2.4B , w h en ph otograp h ed on different planes, are n o t rep resen ted at th e sa m e siz e . T h e rulers w ere ph otograp h ed so th at th e 8 0 -m m m arks lin e up ev en ly . N o te th e v a riation s on each sid e o f th a t p oin t, du e to th e differen t d ista n ces of th e rulers from th e film plane.

encountered in casework. It is unfortunate that so many of the poorer choices are still occasionally used. Two common reasons why a better scale is not used is (1) because the photographer is unaware of what constitutes a proper scale or (2) a proper scale may not be on hand at the crime scene when it is needed. Cloth measuring tapes, sculptured plastic rulers, and metal retractable tapes all have shortcomings when it comes to meeting the criteria of being flat and/or rigid. Coins, pens, pencils, and similar "scales of desperation", even if submitted along with the film to be used as a reference of size, prove to be difficult to use accurately in the darkroom during the enlargement process. Another scale that is commonly used is a paper scale or paper evidence tag bearing the agency's name. These are fine for identifying the photographer or the impression being photographed, but their use as a scale is very limited. Paper scales are very seldom more than 2 in. in length, which is a limitation in itself. In addition, they are often curled or have corners that are bent. This causes inaccuracies when they are the only scale to rely on during the enlargement process. I have also witnessed, on a number of occasions, the practice of making photocopies of paper scales because the supply had run out. Since many photocopying processes do not reproduce items in their precise actual size, scales that have been copied are potentially inaccurate. Photocopies of previously photocopied scales would further compound this.

Footwear Impression Evidence, 2nd Edition

40

Figure 2.5

S om e of th e m an y proper and im proper sca le s used in th e p hotography of im p ression

ev id en ce.

Labels or Evidence Tags In conjunction with the markers that are used in the general crime scene photographs, a label containing the same impression number or other appropriate identifying data (Figure 2.ID) should be placed in the photograph. In cases where there are several impressions, especially if they are at different locations, it will be difficult for the photographer to remember where each of the photographed impressions came from, or the sequence they were in. By labeling or marking the impressions in each photograph with the same numbers used for the general scene photographs, sketches, notes, photographic logs, lifts, and casts, the photographer will be documenting precisely where a particular photographed impres­ sion came from. This will also make it easier for the examiner to collectively examine ail of the photographs that were taken of each impression, as well as any lifts or casts of that impression. The label can be placed either on or next to the ruler.

Tripods It is very important to use a tripod when taking examination quality photographs. The tripod assists in the proper positioning of the camera and provides a steady base that helps

Photography of Footwear Impressions

41

QUAUTIEIS MN SCAËÆS as they relate to the

Photography of Footwear Impressions

CHOICES 1

Thin, Rigid Rulei 9-12 inches long, with 90® right angle; Nonreflective surlace and finely divided scale Thin, Rigid Ruler 6-12" long, Non-rellective surface, finely divided scale

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

no

ye»

no

no

no

yes

no

no

no

Colored or Clear yes fS X Sculptured Plastic Ruler

no

no

yes

no

no

m

not If no yes curled

no

2 = 3

Yardstick or 12" thick Brown Wooden Ruler with Block Numerals

4

Metal Retractable ^ Tape Ruler

5 ®

7 ^

Cloth Measuring Tape

— ^ Paper Label with Scale ^

Pens, Pencils

9 cifc» Coins Miscellaneous Objects such as Business Cards, Paper CUps, Etc.

Figure 2.6

some yes

fd s

yes some no

no

no

no

no

yes

no

m

no

no

no

yes

no

no

no

no

yes

no

yes

yes

no

ye®

some

no

no

no

some some some

C om p arison of th e q u a litie s of th e sca le s pictured in Figure 2.5.

hold the focus and prevent movement of the camera during exposure. In order to avoid a perspective problem when photographing an impression, it is imperative that the film plane in the camera be parallel to that impression. If the impression is not on a level surface, the tripod can still hold the camera in a position so that the film plane will be parallel to the impression. The tripod enables the photographer to do this in the most accurate and efficient manner. The type of tripod best suited for impression photography is one that can hold the camera beneath its center and directly above the impression (Figure 2.4). This allows for easier positioning and adjustments and reduces interference from the tripod s legs. Tripods that cannot be inverted may be more awkward but can still be successfully used. The tripod also leaves the photographer's hands free for other tasks such as the positioning of the light source. When using a tripod, always use a cable shutter release, or the camera timer, to reduce the chance of movement at the time of exposure. If the timer is used, it should be set before focusing the camera. Likewise, caution should be used when activating the shutter release mechanism to assure the camera is not moved out of focus. Trying to take examination quality photographs while holding the camera in your hands may seem quick and convenient, but it is a poor method for this type of photography (Figure 2.7E). Reliance on ones' senses to place the film plane parallel to that impression combined with the continuous movement of the camera while held in one's hand will affect perspective and focus and are likely to result in poor photographs. Further, if photographing impressions as shown in Figure 2.7E, it would be physically impossible to hold the flash at the proper distance and position during time of exposure, without the assistance of a second person.

42

Footwear Impression Evidence, 2nd Edition

(B )

Correct Correct

(D)

Figure 2.7

C orrect and in co rrect tripod setu p s. (A) O n a lev el su rface th e cam era sh o u ld be placed on a tripod w ith th e film p lan e parallel to th e im p ressio n , as p ictu red in Figure 2.4 A . |B) If th e surface is o n an in c lin e , th e cam era sh o u ld be an gled so th a t th e film p lan e is still p arallel to th e im p ressio n . (C) A n in co rrect p o sitio n of th e cam era on th e tripod is d ep icted , sin c e th e cam era is m o u n te d at an a n gle and th e film p lan e is n o t p arallel to th e im p ressio n . (D) A n o th er d ep ictio n of an in correct cam era p o sitio n , w h ic h is o n an in c lin e w ith th e cam era p o in ted straigh t d ow n and n o t w ith th e film p arallel to th e im p ressio n .

Figure 2.7 demonstrates some correct and incorrect positions of the camera over an impression.

Photography of Footwear Impressions

43

(E)

Figure

2 .7 (contin u ed ) (E) T h is e x a m p le, a lso in correct, rep resen ts th e ta k in g a p hotograph w ith o u t u sin g a tripod. P erson s ta k in g p h otograp h s in th is m a n n er w ill se ld o m su c c e e d in g ettin g th e film p la n e parallel to th e im p r e ssio n and w ill a lso h a v e d iffic u lty in avo id in g m o v e m e n t of th e cam era and in k eep in g th e p ictu re in focu s. Further, it w ill be im p o ssib le to correctly u se o b liq u e lig h tin g , u n le ss a ssiste d by a sec o n d person.

Lighting There are many types of lighting that can be used when photographing impressions at crime scenes. Some photographs can be taken with natural lighting, but most require artificial lighting from either a flood light or a camera flash. Natural or ambient light Ambient light is the available or existing light that naturally surrounds the impression. Impressions that show up well under the normal existing light should be photographed initially using that light source. The "through-the-lens" meter is all that is needed to get a proper exposure with existing light. It should be emphasized that although ambient light may indeed produce a seemingly good photograph, more than one method should always be employed. It is always desirable to take additional photographs using a second light source, normally an oblique light source, which usually provides improved detail and contrast over the photographs taken with the natural existing lighting. Reflected light Examination quality photographs should never be taken with the flash mounted on the camera and aimed directly at the impression. This causes a reflection of the light from the flash, back into the lens. It is known as "flash-bounce" and results in an overexposed portion of the photograph as well as reduced contrast. Cameras that are equipped with a built-in flash, which cannot be turned off, should therefore not be used for this type of photography. Sometimes a detailed impression can be seen well by the human eye in the ambient light that surrounds it, but additional light is needed for the impression to record well on the film. A flood lamp or camera flash which is reflected off the ceiling or wall or which.

44

Footwear Impression Evidence, 2nd Edition

on a flash extension cord, is directed at the impression at a 45° angle from at least 4 to 5 ft away can increase the light surrounding the impression in the same manner as the existing ambient light and allow a better exposure to be made. In other situations, the impression can only be seen with the reflected ambient light, such as from a window or overhead light fixture, but the impression is only visible when viewed from an angle. If a camera is placed directly over the impression, the impression, when viewed through the lens, is almost invisible and is therefore not able to be photo­ graphed. Sometimes impressions of this type can be photographed by using a pair of polarized filters, one between an oblique flood light source and the impression, and one between the camera lens and the impression. That technique is a possible studio solution to the problem and is not normally used at the crime scene. A last resort is to photograph an impression of this type using the reflected ambient light and to photograph the impres­ sion at the angle from which it is most visible. When photographing the impression, a rectangular ruler or a right-angled ruler, such as the one shown in Figure 2.5, may be positioned around it so that the perspective problems that will exist in this photograph might possibly be corrected. It is difficult to take detailed photographs of impressions of this type, since the camera usually needs to be some distance away from the impression. Hopefully, the original impressions of this type will be retrieved or lifted or enhanced after photography. Oblique light. More often than not, an impression, although visible and photographable with existing ambient or reflected lighting, does not allow its maximum detail to be recorded with that lighting. By using oblique light, a greater amount of contrast and detail can be provided in that photograph. To supply oblique lighting, either an electronic flash or a flood light can be positioned at a low angle-of-incidence relative to the surface being photographed. Oblique lighting is also commonly referred to as "side lighting". Oblique light, in the instance of three-dimensional impressions, creates shadowing between the high and low areas of the impression, which in turn provides a greater amount of contrast between those areas in the photograph. As a result, the shape and contours within the impression will be better revealed. In the instance of impressions in soil, sand, or snow, the best angle for the oblique light, i.e., the one providing the best contrast, will vary with the depth of the impression. The deeper the impression, the higher above the ground the oblique light will need to be positioned. In more shallow impressions, the oblique light will be positioned closer to the ground (Figure 2.8). For two-dimensional impressions, such as those in dust or residue, the oblique light is most effective at a very low angle, and must sometimes be positioned on the ground so the light is just grazing the impression. This will cause the light to be reflected off the dust or residue particles and up into the camera lens (Figure 2.9). Any experienced footwear examiner will recognize that the failure to properly use oblique light is one of the most serious mistakes encountered in reviewing photographs of footwear impressions. Oblique light should always be used when photographing threedimensional impressions and for most two-dimensional impressions^ particularly those in dust or residue. The illustrations in Figure 2.10 and 2.11 display the difference in results when oblique lighting is used and when it is not used. Using oblique light with three-dimensional impressions. To photograph a three-dimen­ sional impression, first determine the optimal height (angle) for the oblique light source. To do this, direct a flood light, flash light, or other bright light source across the impression.

Photography of Footwear Impressions

Height of light from floodlight or flash should be adjusted as needed to create best contrast in impression

Different amount of light is reflected from shadowed and non-shadowed areas providing greater contrast

(Impression)

Figure 2.8

45

Oblique light photograph of three-dimensional impressions

O b liq u e lig h t p h otograp h y of th ree-d im e n sio n a l im p ressio n s.

Light is reflected off dust particles and into camera

■ ^ t* t

Light from floodlight or flash held very low to ground

(Impression)

Oblique light photograph of two-dimensional impression Figure 2.9

O b liq u e lig h t p h otograp h y of tw o -d im e n sio n a l im p ressio n s.

Vary the height of the oblique light source from the ground up to about 45° until you find the position that seems to provide the best shadowing. Remember that the photographic reason for using oblique light in a three-dimensional impression is to improve the contrast in the photograph by shadowing the low areas in the impression while illuminating the high areas. Therefore, if the impression is shallow, the oblique light source must remain at a fairly low position or else it will result in illumination of the entire impression. If the impression is deep, the oblique light must be raised higher or too much of the impression will be shadowed. Figure 2.11 shows four photographs of the same impression. Figure 2.11A was taken with existing overhead lighting and no oblique lighting. As a result, the contrast is very poor. Figures 2.1 IB, C, and D were taken with the oblique lighting at different heights, at angles of 10°, 25°, and 45°, respectively. The position of the flash at 10° and 25°, for this

46

Figure 2.10

Footwear Impression Evidence, 2nd Edition

Photographs of heeJ im p ressio n in d u st (A) w ith and (B) w ith o u t o b liq u e lig h t. T h e heel im p ression is n o t v isib le u n le ss o b liq u e lig h tin g parallel to th e su rface is used.

Photography of Footwear Impressions

47

|A)

(B )

F ig u r e 2 .1 1 Four photographs of th e sa m e im p ression w ith th e lig h t at differen t h eig h ts. T h e use of an ob liq u e ligh t so u rce at th e proper h eig h t is of great im p ortan ce w h en p h otograp h in g th ree-d im en sio n a l im p ressio n s. (A) w as tak en w ith e x is tin g overh ead lig h tin g and no o b liq u e light. (B) w as taken w ith o b liq u e lig h t at 10° and (C) w as ta k en w ith o b liq u e lig h t at 25°. (D) w as taken w ith o b liq u e ligh t at 45°. T h e sm a ll go lf spotter, used as a ligh t sou rce in d ica to r is located b etw een th e ruler and th e im p ressio n and p rovid es a reference to th e d irectio n and ap p roxim ate angle of th e ligh t. N o te th e len gth of th e sh a d o w ca st by th e g o lf sp otter in crea ses as th e ligh t angle d ecreases.

particular impression, provided better contrast than with the flash in a position of 45° or with existing overhead lighting. Once the desired height of the oblique light has been determined, it will become the height that the camera flash is held at when photographing the impression. The distance of the light source to the impression should be approximately 4 to 5 ft to allow for an even distribution of light. If the camera is equipped with a flash but does not have a long extension cord that will enable that flash to be positioned at the proper height and distance, it will be impossible to take proper photographs using oblique lighting. Even when the camera is equipped with a long extension cord, poor photographs can result when a tripod is not used and the camera is held by hand since it is virtually impossible for anyone to properly hold and position a flash 5 ft from an impression at the proper height and still properly hold the camera in focus directly over the impression. Also, many extension cords for 35-mm cameras are only 3 ft in length, which is inadequate for this type of photography. If only 3-ft extension cords are available, connect and tape two 3-ft extension cords together.

Footwear Impression Evidence, 2nd Edition

48

(C)

(D)

-îîa!»,. ,- '*

' ■\:r'^’’'

Figure 2.11

(continued)

The importance of positioning the flash at a distance of 4 to 5 ft from the impression and aiming it evenly across the impression must be re-emphasized. If the flash or light source is not positioned or not aimed so that it will disperse light evenly across the impression, uneven lighting will occur. Two examples of uneven lighting would be (1) aiming the flash at the impression at an angle so that light results in a bright, washed out, and overexposed area of the photograph, and (2) positioning the oblique light too close to one side of the impression, so that too much light is on the side of the exposure closest to the light source and too little light is on the side farthest away from the light source. Some examples of uneven lighting are shown in Figure 2.12. Figure 2.12A was obtained using a flashlight as an oblique light source. The quantity of light and the uneven disperse­ ment of light from a flashlight are not sufficient to be used for this type of photography. Figure 2.12B resulted when an electronic flash was both too close to the impression and was improperly angled toward the ground on the near (heel) side of the impression instead of evenly across it. This resulted in greater exposure of the heel area in comparison to the toe area. When photographing three-dimensional impressions, particularly those that are deep, the shadowed areas create better contrast, but also may result in the loss of important detail in the shadowed areas. To partially recover some of that detail without losing the contrast, some light can be reflected back into those areas through a technique known as

Photography of Footwear Impressions

49

(A)

(B )

Figure 2 .1 2

T h e o b liq u e Light so u rce sh o u ld be at lea st 4 to 5 ft from th e im p ressio n and sh o u ld be a flood lig h t or an e le c tr o n ic flash. (A) is an ex p o su re m ad e w ith a fla sh lig h t, w h ic h provided u n even and inadeq u ate ligh t. (B) is an ex p o su re m ad e u sin g an e le c tr o n ic flash held to o c lo s e to th e im p ression and aim ed at th e h eel sid e of th e im p ressio n in stead of e v e n ly across the surface. A s a result, th e p ictu re is overex p o sed at th e h eel end and u n d erexp osed at th e to e end.

fill lighting. This is accomplished by positioning a piece of white chart board perpendicular to the part of the impression farthest from the oblique light source so it will reflect some of the oblique light back down into the impression. If desired, the use of an inverted thumb tack or golf spotter, shown in Figure 2.11, can be included in the photograph to show the direction of the shadow cast by the oblique light source. The golf spotter may be placed on the ruler. It should never be placed in the impression itself. This method of using a light source indicator was first suggested by Hamm (1982). Its purpose is to provide the examiner with information, so that the same shadow effect could be recreated in a photographed known impression, should that be necessary. Golf spotters, thumbtacks, and other items, when used as a light source indicator, can help the examiner interpret and re-create the direction of light and are recommended for those reasons only. They are not recommended for use as scales. Although there may be ways to mathematically calculate the depth of an impression by the length of the shadow

50

Footwear Impression Evidence, 2nd Edition

cast by a light source indicator of known height, this may not be as certain or as easy as it sounds for most photographers. Errors could be caused in photographs of impressions on sloping or uneven ground. For instance, there would be no reasonable way for an investigator or examiner to know whether the entire crime scene is on a 5° slope or if the impression s surface was uneven where the light source indicator was placed. It should also be noted that a circular golf spotter or thumbtack is not preferred by most photographers for accurately enlarging photographs to natural size and should not replace, but only supplement, the linear ruler scale. Using oblique light with two-dimensional impressions. Two-dimensional impressions in dust or residue should also be photographed using oblique light. Since tw^o-dimensional impressions are enhanced by light being reflected off the dust particles and into the camera, the light source in those cases almost always works best when positioned on or near the surface (Figure 2.9). The distance of the flash or flood light source should be approximately 4 to 5 ft from the impression to assure even lighting. If using a flood lamp, it should be positioned near or on the surface to provide the maximum enhancement. The electronic flash can be placed either near or flat on the ground so the light is nearly parallel to the surface. It should be placed on the manual setting to provide the maximum light output. Most cameras have automatic exposure features which are useful for taking these types of photographs. The shutter will stay open for the proper exposure, dependent on the light reflected from the impression. However, if using an oblique light source that is positioned to graze the impressioned surface and if using manual exposures along with a light meter, it will usually be necessary to open the f-stop on the camera 4 to 5 times more than the setting indicated by the light meter. Even when using the automatic exposure cameras, always take multiple exposures while slightly varying the position and angle of the flash light source. This will assure a better chance of success. If the two-dimensional impression is on an interior surface, the interior lights should be turned down or off to maximize the effect of the oblique light flash. Should the interior light be from exterior sources such as light entering a window, or the two-dimensional impression be outside, attempts to reduce that ambient light should be made as described elsewhere in this chapter and as illustrated in Figure 2.14. Number of exposures. Whether using manual or automatic settings when photograph­ ing a two-dimensional or three-dimensional impression, you should take several exposures of each impression. It is difficult to accurately calculate or guess the best f-stop and light angles in any oblique light situation. This is particularly true with two-dimensional impres­ sions. The practice of taking multiple exposures is commonly used to ensure that some photographs have been made with the ideal exposure and lighting. The extra exposures are added insurance that the impression has been recorded well. Additionally, the slight variation in the position and angle of the light source with multiple exposures will provide more information than only one exposure of that impression. When taking multiple exposures, the focus should be checked before each exposure. After the exposures are made from the first oblique light position, the oblique light source should then be moved to two more positions around the impression, and several additional exposures should be made at each position, again varying the f-stop and check­ ing the focus for each exposure. The three positions should be at least 100° apart. For example, three positions at which to place a light source might be 30°, 130°, and 230° on a circle around the impression. This procedure is depicted in Figure 2.13 along with photographs with the light source taken in different positions. The same would apply for

Photography of Footwear Impressions

51 -W '

V-'(A) ;/

(B)

(C)

Figure 2.13

T h e o b liq u e lig h t so u rce sh o u ld be placed in th ree d ifferent p o sitio n s at least 100° apart. In th is ex a m p le, (A) is at 70°, (B) is at 190° and (C) is at 290°. T h e varied p o sitio n s w ill c o lle c tiv e ly capture m ore detail than p h o ­ tographs from o n e p o sitio n alon e. T h e e x a m ­ p les sh o w n in (A), (B), and (C) are su m m a rized in (D).

two-dimensional impressions. Since the light is low and often grazing the surface, this is mainly to assure that an uneven floor or other obstacle does not interfere with the light and cast a shadow across the impression. By moving the light source to different positions around the impression, shadows will be cast in three-dimensioual impressions or light will be reflected off the dust or residue in two-dimensional impressions in different ways. The combination of the photographs taken with the light source in the three different positions

Footwear Impression Evidence, 2nd Edition

52

L ight S ource' in Third P osition

L ight S ource r ^ A in First

290“

T flT^^^osition

270

(D)

L ight Source, in S eed

P osition

After determ ining the proper height of the oblique light source, photograph with the light source in three different positions with at least 100 degrees separation.

Figure

2 .1 3 (con tin u ed )

will collectively depict far more detail and information from the impression than photo­ graphs with lighting from one side alone. Although examination quality photography at the crime scene does not sound like an easy task, once the basic principles are understood and the proper procedures are estab­ lished, they are easily and effLciently accomplished in minimal time and will result in superior photographs. Taking several photographs of each impression in accordance with the above instructions assures a greater likelihood of capturing the maximum detail in each impression. This is particularly true and important in those instances when subse­ quent lifting, casting, or enhancement may not be possible and the most important rep­ resentation of the evidence will be the photographs. Film is cheap in comparison to your time, the total cost of the investigation, and the seriousness of the crime. Special problems with oblique light. When using oblique light in situations where there is a great deal of ambient light, such as is often the case outside on a sunny day or even a bright cloudy day, it is necessary to shield the impression in some way from that bright ambient light source. The light can be shielded in a number of ways, including using a piece of cardboard, the shadow cast from a fellow officer, or by draping a black cloth over and around the tripod. Anything that will block out some of the bright light to allow the electronic flash to become the dominant light source will improve the resulting photo­ graphs. Figure 2.14 shows a simple way of achieving this. After the camera has been set up on the tripod, a black cloth is draped around the sides of the tripod to make a partial tent. This will block out a considerable portion of the bright ambient light and will allow for a picture of greater contrast to be taken with the oblique light provided by the electronic flash. Figure 2.15 shows the difference this procedure can make. Figure 2.15A is an impres­ sion photographed with the existing sunlight. Figure 2.15B was taken with an oblique light source and the existing natural sunlight, but no sun screen. In Figure 2.15C, an oblique light source has been used with a sun screen.

Photography of Footwear Impressions

53

Figure 2 .1 4

W hen th e a m b ien t (existin g) lig h t is to o in te n se , su ch as on a su n n y or bright hazy day, a p iece of black clo th or o th er m a k e sh ift item can be u sed as a su n screen by draping it around th e tripod. T h is w ill b lo ck o u t m u ch o f th e a m b ie n t lig h t and w ill a llo w th e o b liq u e ligh t from th e elec tr o n ic flash to be u sed m ore e ffectiv ely . T h e o b liq u e lig h t from th e flash can be directed in to th e open sid e of th e te n t as v ie w e d here.

Inversion Effect Occasionally, when viewing a photograph of a three-dimensional impression, the actual indented areas of the impression will appear to be raised (see Figure 2.16). By rotating the photograph 180°, the same areas will then appear indented. If several persons were to view this photograph simultaneously, some would perceive the impression as indented, while

54

Footwear Impression Evidence, 2nd Edition

» * 'M - X ' . ■' ■'

2^ ■'-, ÆK'

(B)

,-Ÿ: ■ *' l i l w ■f

â -i ■'it ’*' liïf'.V^ •I

Figure 2.15

Im pression p h otograp h ed (A) w ith e x is tin g su n lig h t w h ic h h ap pened to be at a low an gle and no sun screen , (B) w ith e x is tin g su n lig h t co m b in e d w ith o b liq u e flash h ut no sun screen , and (C) w ith an o b liq u e flash and sun screen . T h e c o m b in ed o b liq u e lig h t and sun screen (C) p rovid es greater co n tra st and th erefore greater d etail.

Photography of Footwear Impressions

55

'f. *





v

V

i

i

'¡VMM :

.# 5 ^ ' (C)

1 / / :

-P ;i

■■ % mm

f

HP

-

I 1,

'•' y-f'IF f ifSP?'

jf ■ '.:'

'JjEZj ÏÉI

-

■ ;'l'.V-7- .C 4Í|¿í1& ' . 0 4 ^ ‘^ W ^ W ^ ñ 5-

H .........

:tV ■-í#i

,

IÍM ÍjÉ i¿ jiÍi» ii

F ig u r e 2 .1 5 (contin u ed )

others may perceive it as raised. This phenomenon is referred to as the "inversion effect," which is merely an optical illusion. The inversion effect is occasionally encountered in the photography of three-dimensional impressions, particularly those taken with strong nat­ ural oblique light. It does not interfere with the examination and interpretation of pho­ tographed impressions.

Focusing the Camera The auto-focus feature of a camera can be used for examination quality photography if it is focused on the impression itself and not the scale. Manual focus provides better control of the focus plane and position. It is hard to imagine that anyone who knows how to use a camera and does so on a regular basis would take photographs that were out of focus; however, poor focus is one of the most common mistakes encountered in photographs of impression evidence. One reason for this is obviously simple carelessness, i.e., forgetting to focus the camera. Another reason occurs when the camera has been focused on the ruler or label instead of on the impression. Although both the ruler and the bottom of the impression should theoretically be on the same plane, there will always be minor differences. The bottom of the impressiotiy and not the ruler or label, should always be the object of focus. Out-of-focus pictures can also occur when the film plane is not parallel to the surface of the impression, causing part of the impression to be out of focus when another part is in focus. Whenever photographing three-dimensional impressions, the f-stop should be at a setting with a small aperture size, such as fl6 or f32, to maximize the depth of field. This will create a larger range of focus.

56

Footwear Impression Evidence, 2nd Edition

Figure 2.16 T h e in version effect is an op tica l illu sio n w h ich is freq u en tly e n co u n tered in photographs u tiliz in g o b liq u e ligh t. Indented areas of a photograph w ill appear raised w hen v iew ed on e w ay b ut appear depressed w h en inverted . If the camera is held by hand and not with a tripod, it will not be possible to photograph the impression properly. Common sense would dictate that any photographer bending over an impression, checking the exposure, while holding the flash to the side, and then trying to hold the camera in focus, is going to have many out of focus photographs due to unintentional movements and fatigue caused by attention to all those tasks. Even in cases where the camera is positioned properly on a tripod, focus can be lost due to settling of the tripod legs into the soft ground or if the tripod is unintentionally disturbed. Examination quality photographs, because they are concerned with fine detail and because they will be enlarged many times, need to be in sharp focus, not just approximate focus. A shutter cable release or the camera self timer should also be used to assure that the camera remains still and stays in focus when the shutter is activated. Since there are many ways to lose focus, the last thing that should be done before every exposure is to check the focus of the camera.

Photography of Footwear Impressions

57

H Figure 2.16

(continued)

Checklist For Examination Quality Photography Step-by-step guidelines set forth in Figure 2.17 are useful for taking examination quality photographs of impression evidence. Having a photographic kit prepared in advance will help in the proper photographic treatment of evidence. Below is a list of items that should be included in a crime scene kit to cover general crime scene photographs and examination quality photographs: Camera(s) with manual focus and interchangeable lenses Normal macro-lens and variable zoom-lens Cable shutter release (if applicable) Electronic flash Flash extension cord that is at least 6 ft long Focus aids if needed Tripod (preferably the invertible type) Fine-grained films (black-and-white and color) Rigid flat ruler(s) for use as a linear scale Right-angled ruler as a linear scale

Footwear Impression Evidence, 2nd Edition

58

Procedure Checklist for Examination Quality Photographs The following step-by-step guidelines are useful for taking examination quality photographs o f impression evidence: STEP

1

STEP 2

STEP

STEP

STEP

3 4 5

STEP 6

STEP

STEP

STEP

stepI

7 8

9 0

Identify the impression you wish to photograph and place a good linear scale such as a ruler next to and on the same plane as that impression. Place a label in the picture to identify which impression you are photographing. Load a camera capable o f manual focusing with fine-grained color or black and white film, having an ISO o f 125 or less. Check the ISO setting on the camera if it does not have an automatic feature. Attach a cable shutter release if one is being used. Place the camera on a tripod and position it directly over the impression. Adjust the height o f the camera or adjust the zoom lens so the frame is filled with the impression and ruler. Make sure the camera is positioned so the film plane is parallel to the impression. Check the f/stop. For three-dimensional impressions, the f/stop should be set on f / 16 or f/22 to allow for a greater depth o f field. Attach the electronic flash to the camera with a 6-foot or longer extension cord. With a flashlight or flood lamp, determine the height o f the light as besi for each impression. Block out any bright ambient light with a sun screen to maximize the benefit o f the oblique light. Use a cable shutter release or set the automatic timer feature to prevent movement o f the camera during exposure. Focus the camera. THE FOCUS SHOULD BE ON THE BOTTOM OF THE IMPRESSION, NOT ON THE RULER. Take an existing light or refiected light photograph if desired. U sing the shutter release or activating the self-timer, hold the flash 45 feet from the impression at the pre-determined height and carefully aim the flash evenly across the surface of the impression al the time of exposure. Take the necessary exposures, then move the light to another position, adjusting the sun screen as needed and repeat steps 7 through 9.

Remember to Use a Scale in Every Photograph and Always Focus F ig u r e 2 .1 7 Procedure c h e c k list for ta k in g e x a m in a tio n q u a lity photographs.

Labels and writing instruments Numbered markers or cones for general scene photography Wliite chart board for fill lighting Black cloth or other suitable sun screen Lens filters

Casting T hree-D im ensional Footwear Im pressions

3

Decades ago, the casting process was the predominant method for recovering three-dimen­ sional footwear impression evidence. Although the impressions were also photographed, the bulky and less sophisticated photographic equipment, combined with the slower films of those times, made photography more difficult, less available, less convenient, and often less successful than casting. Most of the older literature on casting footwear impressions advocated the use of plaster of Paris. The casting procedure required the use of about 5 lb of plaster of Paris for the average footwear impression. This translated into an inconvenient, messy, and time consuming procedure, especially if this process had to be repeated for several impressions. In addition, and most important, because the plaster of Paris was not a sufficiently hard form of gypsum, much of the fine detail, usually necessary for positive identifications, was routinely washed away when the soil was cleaned from the cast. In the 1960s, 1970s and 1980s, as improved photographic equipment and films made photographing footwear impression evidence easier and more convenient, the use of pho­ tographs to recover footwear evidence increased while the practice of casting footwear impressions declined. Many departments simply abandoned the practice of making casts. In recent years, better quality casting materials and more simplified procedures have changed the casting of footwear impressions into an easier, more convenient, and successful process. Most important, examiners recognized that casting can capture additional detail over photographs and is therefore essential to a thorough examination. As a result, casting has again become a widely used and routine method of recovering three-dimensional impression evidence.

Introduction To Casting Definitions Three-dimensional footwear impressions are those that have significant depth in addition to length and width. They are most commonly found outdoors in soil, sand, and snow. They can range from being very shallow to several inches deep. Due to the various textures, compositions, and conditions of soil, sand, and snow, the degree of detail that can be transferred from the footwear and retained by the substrate will vary tremendously. The detail in some of these impressions may be very coarse and may not even reflect the gross

59

Footwear Impression Evidence, 2nd Edition

60

characteristics of size and design. Other impressions may be unbelievably clear and reflect microscopic detail transferred from the footwear that made them. Casting, in the simplest of deflnitions, is the filling of a three-dimensional void. In the case of forensic footwear impression evidence, casting may be defined as the filling of a three-dimensional footwear impression with a material that will acquire and retain the char­ acteristics that were left in that impression by the footwear. The Importance of Casting Whereas photography is worthwhile and necessary, casts are capable of capturing additional qualities that are present in three-dimensional footwear impressions but are not revealed through photography. A cast is an actual life-size molding of the impression. It reveals every characteristic including the unevenness of the surface and the variance in the depth of the impression. It is capable of reproducing all of the detail that is present in an impression, including microscopic detail, which can later be closely examined in the laboratory. There are no focus problems or lighting problems, as is often the case with photography. Additionally, there are no size or perspective problems. Modern casting materials have excellent dimen­ sional stability. A dental stone cast is, for all practical purposes, the true size of the impression it filled. Because the cast is a positive likeness of the footwear which made the impression, it can be compared directly with the known footwear. In the courtroom, the cast provides a tangible piece of evidence that is easily displayed and understood by the jury. Articles written on the methods of retrieving three-dimensional impressions have always supported casting. None that I am aware of have stated that casting was unnecessary. Over 50 years ago, an article in the FBI Law Enforcement Bulletin stated. Casts are considered superior to photography since they reproduce all three d im en sio n s o f the im pression and thus perm it a m ore detailed exam ination than could be m ade from a photograph (1945).

DeHaan (1982) pointed out that ‘‘useful information is more often found in the cast than in the average photograph. A similar opinion is expressed by Mansfield (1970): "For impressions outside, the ... cast provides better evidence than the photograph because of its perspective depth." In their book. An Introduction to CriminalisticSy O’Hara and Osterburg (1949) state, "By far the best means of studying an impression in mud, snow, or other surfaces is that of the ... cast. Quite frequently, a properly made cast will offer much more information to the eye than the impression itself." Kirk (1974) is quoted as saying “Although the photograph of an impression is of value for purposes of record, and even for comparison of detail, it is less useful than is a good cast of the impression.” Finally, Cassidy (1980) comments, “The number of accidental characteristics recorded in the three-dimensional impression will surprise you.” My own experiences have demonstrated that casts of footwear impressions are extremely valuable as a means of recovering the maximum amount of detail from an impression and they provide the examiner with far more information than photographs alone. Whenever there is a three-dimensional impression at a crime scene, it should be cast!

Casting Three-Dimensional Footwear Impressions

61

9 "Photography and casting supplement one another to give the maximum amotmt of information about an impression to the examiner"

E x a m in a tio n Q u a iity P h o to g r a p h s

C a stin g

■ Show im pression a s it |■ Gives Life-like and w as a t the crim e scene actual-size m olding along w ith any rocks, of th e original im pression stick s or o th er debris including uneven which m ay be in, surfaces a n d d ep th s aro u n d or part of the im pression | ■ Gives reproduction of microscopic ■ Show th e condition characteristics a n d detail of th e im pression | ■ In deep im pressions, gives reproduction of ■ In som e in stan ces, ch aracteristics of the su c h a s w ith sides of outsoles a n d im pressions in m idsoles of th e shoe extrem ely coarse w hich are u su a lly not re ­ surfaces, photographs produced in photographs m ay re p re se n t the im pression b e tte r th a n ■ No focus or scale a cast problem s

IB ack u p

castin g

■ Provides tangible 3— dim ensional evidence ■ B acks u p photography

iiiiiiiiiiiiTnifîiiiniiiMmiiiiifiiïiirm F ig u r e 3 .1 Photography and c a stin g su p p le m e n t on e another.

Benefits of Casts Over Photographs Both photography and casting provide a great deal of information about an impression, but each can also supply some information that the other may not. As summarized in Figure 3.1, photography and casting supplement one another, and together, provide the max­ imum information about an impression to the examiner. As an illustration of how a cast may provide information not easily obtained from a photograph. Figure 3.2 depicts the mechanics of a common scenario in three-dimensional impressions, that of an impression being made in a soft, yielding surface. As the heel strikes the surface (Figure 3.2A), some of the surface material is pushed forward into a mound. As the impression continues, the shoe will roll over the mound (Figure 3.2B) and push off the other side to complete the impression (Figure 3.2C). This can be easily demonstrated by walking in sand, first very slowly, and then gradually faster. The faster the walk, the harder the heel will strike and the deeper it will dig into the sand. The deeper the heel goes, the greater the amount of sand that will mound up. The resulting impression will not be a level or flat impression. When photographs are taken of this impression, two problems will immediately arise. First, because the impression is not flat, it will not be possible to place a ruler on the same

62

Footwear Impression Evidence, 2nd Edition

(A)

---------------------

IB)

mmBims ofmi

OVERMOliNO

F ig u r e 3 .2 A typ ical th ree-d im en sio n a l im p ressio n in a soft, y ie ld in g surface. T h e h eel strik es th e surface and p u sh es th e soil forw ard (A). A s th e step c o n tin u e s, th e sh o e rolls over th e m ou n d of soil (B) and th en p u sh es off (C). T h e resu ltin g im p ressio n has an u n ev en surface and appears shorter in a photograph than th e sh o e th a t m ad e it (D).

plane over the length of the entire impression. The impression's varied depth will therefore affect both the scale factor and the ability to have the film plane parallel to the full impression. This will be a negligible variation in most cases, but in deeper impressions, it can be more pronounced. Second, photographs of the impression would depict the length of the impression as dimension B in Figure 3.2D, which is shorter than the actual outsole of the shoe that made it as represented by dimension A in Figure 3.2D. A cast of the impression will help to account for this unevenness and will accurately bring all of the three-dimensional aspects of the impression to the examiner, assisting in the overall com­ parison and evaluation. Figure 3.3 depicts a second type of three-dimensional impression, i.e., that made by a relatively even strike of the footwear on a more firm surface. The impression is shallow and any unevenness would be negligible. Photographs of this impression would be in agreement with the size characteristics of a cast of this impression. But even in such a simple impression as this, the more minute characteristics, no matter how capable the photographer was, are often not recorded well through photographic means. Figure 3.4 illustrates one possible reason why. The majority of significant detail and identifying characteristics are present on the bottom surface of a shoe sole because these areas touch

Casting Three-Dimensional Footwear Impressions

63

(C)

ID)

Figure

m mmimmthe mtummmmmm * r is mmshoe mmn w

3 .2 (continued)

the ground most frequently. Thus, the areas with the most important detail are represented in the deepest areas of the three-dimensional impression, and are often hidden instead of enhanced by the shadows present in photographs taken with oblique light. If the impression is photographed with the oblique light source from three different positions or if a “fill card” is used to recapture some of the detail in the shadowed area, it may be possible to capture most of the detail of those minute characteristics. However, the crime scene photographer does not know where those characteristics are present as he or she photo­ graphs each impression. No matter how well intentioned the photographer may be, all of the characteristics in an impression will not be photographically retrieved. In fact, in the day to day practice of photography at crime scenes, much of this minute detail is routinely lost. Casting is the best way to ensure that this detail is preserved. An illustration of this

64

Figure 3.3

Footwear Impression Evidence, 2nd Edition

An ev en im p ressio n in a firm surface.

xOBLIOUE LIGHT •' '■’ '■s h o e '''’''''"'’' IMPRESSION

POSSIBLE LOSS OF DETAIL IN PHOTOGRAPHS TAKEN WITH OBLIQUE LIGHT

A iC U TS HIDDEN IN l i l f SHADOW OF miOBLIQUE LIGHT Figure 3.4

S hadow s ca u sed by o b liq u e lig h t p h otograp h y can ob scu re so m e ch a ra cteristics in th e im p ression .

Casting Three-Dimensional Footwear Impressions

65

(A)

Figure

3 .5 P hotographs of a very enlarged area of a cast (A) and sh o e (B) sh o w in g m icr o sc o p ic detail reproduced in th e cast.

fine detail can be seen in Figure 3.5, which depicts a very enlarged portion of a small segment of a cast of an impression and the corresponding area on the shoe that made the impression. Once this detail is retained in a cast, any segment of the cast can be examined and photographed in the laboratory with appropriate lighting to further enhance the detail.

Casting Materials C hoice of Casting Material A search of the literature on the casting of footwear impressions reveals that many casting materials have been used at one time or another and with varying degrees of success. Those materials used have included various silicones, moulage, paraffin wax, alginates, plaster of Paris, and dental stones. For three-dimensional impressions, silicone-based materials are expensive, often do not adequately release the material (such as soil) in which the impression was made, and are often too thick to flow properly into the impression. Most silicone based casting materials also take a significantly longer time to cure. Although certain impressions, such as those in heavy clay soils, could probably be cast with more fluid silicone materials, the silicone would not rival better choices. Paraffin wax is not suitable for a number of reasons. It is inconvenient to use because of the 20 to 30 min it takes to melt the necessary 1 1/2 lb needed for each impression. It

Footwear Impression Evidence, 2nd Edition

66

_ _ _ _ _ _ _ _ , . , . - n T o - T iif n n iri T ii- ii m i r ii i n n ■ ■ ■ ■ " i - i i M i M ii i i i i r B '

f fj‘/ F

IË I m

Figure

3 .5 (continued)

is also more expensive than other choices. Additionally, paraffin wax does not reproduce the degree of detail that other materials do on the large variety of surfaces in which casting materials are used. Moulage, often mentioned in the older literature, is a hard, plastic-like material that must be heated in a double-boiler until it melts. The hot liquid is then poured into an impressioned area. When it cools, it hardens and can be removed. The process is long and the detail it renders for footwear impressions is not as good as that obtained with gypsum products. For years, softer plasters, such as hobby or modeling plaster and plaster of Paris were the most commonly used casting materials. As is explained later, soft plasters, i.e., those gypsum casting products which are softer and have lower compressive strengths, are not regarded as a desirable material for use in the casting of footwear impressions. Although all plasters have the ability to reproduce fine detail, it is very difficult and in fact, in most instances, impossible, to clean casts made of the softer plasters without serious loss of detail. Further, many have experienced that some of the softer plasters are unpredictable in quality. This may be explained by the fact that modeling plasters and plaster of Paris may have been purchased in small quantities from a local hardware or hobby store, after its shelf life had expired. Casts made from materials such as that, on a single occasion, may turn out chalky, while on other occasions they may turn out soft and wet and resistant to drying. The RCMP Gazette reported “Many casts fail through the use of a poor grade or old plaster, which does not set properly"(1965).

Casting Three-Dimensional Footwear Impressions

67

Denta] stone is a gypsum cement which has been further modified for use in the dental industry. As early as 1950, there is reference to dental stone being used and preferred over plaster of Paris.' Then, Assistant Special Agent-in-Charge E.L. Boyle wrote, I have found generally that for this (casting) purpose, plaster o f Paris is n ot too satisfactory and is too fickle a material even for an h id expert’.... I looked around for so m e other material and hit upon the com m ercial product called C astone .... I have found it a m uch m ore satisfactory casting material than plaster o f Paris. Its detail is 100% better, it is m uch harder, and for sm all casts at least, no su p p ortin g twigs or other m aterial are necessary.

Unfortunately, most persons did not change to dental stone at that time. In recent years, however, dental stone has been used with great success as a casting material for footwear impressions. In 1986, a revised FBI Law Enforcement Bulletin advised, "It is now recommended that only dental stone be used for casting impressions"

Qualities Casting Materials Should Possess To be suitable for casting footwear impressions, and considering the needs of both the person making the cast and the person who will examine it, certain criteria for casting materials need to be met. The casting material should: 1. be capable of reproducing very fine detail, 2. have the fluidity necessary to flow evenly into the impression but not be absorbed into it or pass through it, 3. be able to be cleaned without loss of detail and should release itself from the material in which the impression was made, 4. be reasonable in its cost, 5. be easily obtainable in a consistent form and quality, 6. be easy to mix and use, even under adverse conditions, 7. set in a reasonable amount of time, be durable, and have dimensional stability, 8. not require special equipment or complex procedures, and 9. not have a limited shelf life. As can be observed in Figure 3.6, dental stone meets all of the requirements necessary to be a good casting material. It is easy to use and mix. It requires only a couple of pounds of material to cast a full-size footwear impression. It is hard, durable, and easy to clean without any loss of detail. It is inexpensive, readily available, and does not have shelf-life problems. Another beneficial quality is that it is available in colors. Figure 3.7 depicts an enlarged portion of a cast of an impression made by a new shoe in clay soil. Half of the cast was made using dental stone while the other half was made using a softer grade of gypsum known as plaster of Paris. The cast was allowed to dry for 4 days and was then carefully cleaned. The plaster cast, being softer, lost considerable detail during the cleaning process. The detail on the dental stone cast remained sharp and intact after cleaning.

FBI memorandum, Assistant Special Agent-in-Charge E.L. Boyle, )anuary 24, 1950.

68

Footwear Impression Evidence, 2nd Edition COMPARISON of MATERIALS for CASTING 3-DIMENSIONAL FOOTWEAR IMPRESSIONS Plaster o f Paris

Dental Stone

Silicone

Shelf Life and Quality

U N C ER TAIN

EX CELLENT

V AR IES

Cost

Not expensive

Not expensive

Expensive

Ability to Reproduce Fine Detail

YES

YES

Hard to apply to without damaging impressions

Hardness and Durability

NO

YES

YES

Ability to be Cleaned without Loss of Detail

POOR - due to softness, cannot chemically dean or immerse in water without serious loss o f detail. Brush will destroy detail.

E X C E L L E N T - easy to clean by immersing in water and, if needed, in potassium sulfate solution. Can use soft brush to help clean

V ARIES - depends on surfece and viscosity o f silicone

Positive Identifications with Known Shoe

FEW - because o f loss o f detail when cleaning

M A N Y - retains excellent detail

N O T LIKELY

Amount of Material and/or Water Needed for Footwear Impression

About 5 Pounds o f Plaster o f Paris and approximately 90 ounces o f Water

2 lbs. o f Dental Stone and between 9 to 12 ounces o f water, depending on W P ratio

Approximately 1 ‘/ i to 2 pounds o f silicone plus catalyst

Reinforcement Material Needed?

Y E S- Needed to prevent cast from breaking

N O - Not Needed

N O - Not Needed

Form Around Impression Needed?

Y E S- Needed for thickness so that reinforcement material can be placed within it

N O- Not needed unless used to restrict flow o f material.

N O - Not needed for strength-only if necessary to restrict flow o f material

Application and Ease of Use

Messy and cumbersome because o f quantity needed

Use o f zip-lock bags make use easy and not messy.

Messy to mix with catalyst at scene; longer time to cure

Popularity among Crime Scene Personnel

N O T POPULAR

POPULAR

N O T POPULAR for 3-D Impressions

Figure 3.6 Comparison of materials for casting three-dimensionaJ impressions. Dental stone, or another form of gypsum cement with a higher compressive strength, is therefore recommended for casting footwear and tire impressions. Nevertheless, the common names of plaster and plaster of Paris have been known for so long it has been difficult to convey to all crime scene technicians the reasons and the need for the change to the harder forms of gypsum cement, namely dental stones. About Plasters, Gypsum C em ents, and D ental Stones Gypsum based materials, in the most general use of the word, are all referred to as plasters. Hence, the term plaster is a very general term which includes a//casting products composed of a form of gypsum. However, gypsum is processed in different ways to provide different properties suitable for specific uses. Qualities such as setting time, consistency, fineness, hardness, strength, surface characteristics, and color distinguish the various gypsum prod­ ucts that are given names such as plaster of Paris, molding plaster, gypsum cement, and dental stone. Commercially, they are used to cast many objects such as lamp bases, art objects, molds, novelties, displays, teeth, etc. Figure 3.8 A-C shows the relationship of the various gypsum products in terms of their names, compressive strength, and consistency. Although the overall range of all gypsum products are sometimes collectively referred to

Casting Three-Dimensional Footwear Impressions

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Figure 3.7 A cast of an impression in clay soil made by a new shoe. Half of the cast was made with buff-colored dental stone (the darker side) and the other half with plaster of Paris. The cast was dried thoroughly and then cleaned. Note how the plaster of Paris portion looks washed out (top arrow), contains brush marks (bottom arrow), and has not retained the crisp, sharp detail of the shoe. The dental stone portion has retained all of the original detail.

A.

... - plasters.....................^ [veiy gei^ral tefereoce to ail gypsum products]

B. -«mÊÊÊÊÊmmplaster grade
(CaS04)2 • H , 0 ----- > CaS0 4 ----- > CaS04 110-130°C 130-200°C 200-1000°C Gypsum Plaster Stone (calcium sulfate (calcium sulfate (calcium sulfate dihydrate) beta-hemihydrate) alpha-hemihydrate) Depending on the method of calcination, different forms of calcium sulfate hemihydrate can be obtained and are referred to as alpha- or beta-hemihydrates. If crushed gypsum is heated in an open oven at a temperature of around 130° C, a product called beta-calcium sulfate hemihydrate, but more commonly known as plaster of Paris, results. The beta-hemihydrate requires more water to float its particles for mixing because the crystals are more irregular in shape and are more porous. /4 different method is used to obtain alpha-hemihydrate. Its production includes heating the gypsum mineral in an autoclave under pressure and in the presence of steam. The powder produced by this method contains particles that are more uniform in shape and more dense than the plaster particles. The resulting alpha-hemihydrate requires much less water when mixing and results in a much stronger and harder cast.^ There are many different procedures to produce both beta- and alpha-hemihydrates. According to the gypsum industry,^ there are a wide range of plasters and gypsum cements produced. As indicated in Figure 3.8A, the term plaster is used to generally describe those gypsum casting products that have a consistency greater than 50. Having a consistency greater than 50 simply means they have 50 or more parts water per 100 parts plaster. In Figure 3.8B, note that as the ratio of water to powder decreases, the compressive strength or hardness of the material, measured in pounds per square inch (psi) increases. Gypsum cements (a.k.a., hydrocal, stone, etc.) are products that have a consistency less than 50, meaning they have less than 50 parts water per 100 parts plaster. The name si one generally refers to those gypsum products having a consistency of approximately 35 or less. Stones are further processed or mixed with additives for the specific purpose of utilizing this material in the dental industry, hence the name dental stone. The additives include materials that accelerate the setting time and also that give the various dental stones different colors, so they can easily be distinguished in the dentist’s office. The quicker setting times and addition of color suit crime scene casting applications well. With regard to the casting of footwear impressions, their strength and durability make the stones superior to the plasters. For the crime scene officer, the increased strength of dental stone means it is no longer necessary to pour a cast several inches thick, surrounded by a form and filled with re-inforcement material. When using dental stone, two pounds of casting material will be all that is needed to fill an average size footwear impression. Since the water-to-powder ratio of dental stone is much less than that of plasters, the two pounds of dental stone powder will only require approximately 9 to 10 oz of water. As will be discussed later, dental stone can easily be stored in a zip-lock bag to which a pre-

^ Phillips, R.W., S c i e n c e o f D é n i a i M a t e r i a l s . W. B. Saunders Co, 1991. ^ United States Gypsum Company, Chicago, IL.

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measured quantity of water can be added when needed, thus assuring the proper consis­ tency. Water-to-Powder Ratio (Consistency) The amounts of water and casting powder should be pre-measured by weight. The exact water-to-powder (W:P) ratio will vary with the specific gypsum product, such as dental stone, being used. The W:P ratio, i.e., the quantity of water by weight per quantity of powder by weight, is known as the consistency of the mixture. A “40 consistency” mixture would mean 40 parts of water per 100 parts powder and its W:P ratio would be .40. The W:P ratio is extremely important and relates directly to the density, hardness, strength, and durability of the cast. The higher the W:P ratio, the longer will be the setting time, the lower the compressive strength, and the softer the cast. The following table shows the W:P ratio of a few different gypsum products, varying from a consistency of 100 down to 21. Consistency Pounds water per 100-lb plaster 100 80 57 50 42 38 33.3 30 21

Plaster per pounds water 0 lb. 16oz. 1 lb. 4oz. 1 lb. 12oz. 2 lbs. Ooz. 2 lbs. 6oz. 2 lbs. lOoz. 3 lbs. Ooz. 3 lbs. 3oz. 4 lbs. 12oz.

Dry compressive strength (psi) 650 1400 3000 3750 5500 7000 9750 11000 15000

M ixing The casting process, simply described, involves the combination of the proper proportions of water and casting powder, mixing those together, pouring the mixture in a mold or impression, allowing the cast to set up, and drying the cast. Mixing the casting powder with water is a very important part in producing a cast since the mixing disperses the particles in water. The amount of energy in the mixing process is directly related to the final strength of the cast. “Optimum physical properties are in direct relation to energy input in mixing”, so “hand mixing will not result in a ... cast with the best properties.” Mixing by hand provides less energy than mixing in industrial usage, where special mixing equipment is used. The significance of this is as follows. The qualities published on the container of casting materials, including the compressive strength (psi), are based on data obtained through industrial mixing and drying. Since the resultant qualities and hardness (psi) of the cast are directly related to the amount of energy that goes into mixing, hand mixing will result in a cast of less compressive strength than the published data. For instance, for a dental stone product that states on its container that it has a compressive strength of 8,000 psi, only approximately 50% of that strength (4,000 psi) might be realized when mixed by hand and air dried instead of through industrial mixing and drying. The significance of this is that a gypsum product should be used that has a compressive of at least 8,000 psi to assure it will be sufficiently hard to retain all of its detail when cleaned. Miller, L., United States Gypsum Company, personal communication, 1997.

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According to the gypsum industry, the casting powder should be added to the water. It should be added by sifting the powder into the water as opposed to dumping it all at once. ''An ideal plaster mix is one in which the plaster particles are completely dispersed in the water to produce a uniform, homogenous slurry.”^ However, the zip-lock bag method, which involves the addition of water to the powder in a plastic zip-lock bag, is satisfactory, if the exact quantity of water is added all at once and mixing begins immedi­ ately.^ Casting materials begin to set as soon as the water and powder come together. For this reason, it is necessary to combine the proper amounts of water and powder at one time and begin the mixing at once. This can only be done if the powder and water portions are premeasured. As soon as the water is added, the mixing should be continuous for 3 to 5 min. Allowing the material to stand and soak before mixing is not necessary.^ Watering Out The crime scene officer should be aware of the process known as watering out. Watering out is a term that describes the separation of water after mixing. It is often observed after the cast is poured. It refers to a situation where water rises to the top surface of the cast. This occurs when the plaster was mixed at the wrong W:P ratio or was not mixed for a sufficient duration. If a quantity of powder and water are mixed in a bag and the material is thicker during the second half of the pour, either the W:P ratio is wrong or it was not mixed enough.

Methods Of Casting With Dental Stone Have Casting Materials Available A major reason why casts are often not made at crime scenes is simply that no casting materials are on hand when needed. Obtaining the necessary casting materials and supplies beforehand and having them readily available and pre-measured is essential. It is not convenient, practical, or good planning to have to hastily look for casting supplies while trying to conduct other matters of importance at the crime scene. The following materials should be obtained and kept available:

1.

Dental stone, or other suitable form of gypsum cement having a consistency of 35 or less, and a psi of 8000 or more, either in bulk form or pre-measured into several zip-lock bags (2 lb per bag). 2. Water and a graduated cup, so the proper pre-determined amount can be added. 3. Form material (only needed on sloped surfaces). 4. Spoon or flat stick (optional, for bulk mixing in a bucket). 5. Rubber mixing bowl or bucket for bulk mixing.

^ United States Gypsum Company, Chicago, IL. ^ Miller, L., United States Gypsum Company, personal communication, 1997. ^ Miller, L., United States Gypsum Company, personal communication, 1997.

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(A)

Figure 3.9 Dental stone and water are all that are normally needed to make a cast (A). Figure 3.9A depicts the few items needed to prepare a quality cast of a footwear impression. In most instances, only dental stone in a zip-lock bag and water are needed. Dental stone is readily available from local dental supply houses. If local sources are not available, dental stone can be easily ordered and shipped through the mail from several national suppliers. The actual prices of softer plaster, such as plaster of Paris, are essentially the same as prices for the harder gypsum materials, such as dental stone. Upon consider­ ation that only 2 lb of dental stone are needed per impression compared to the 5 lb necessary for plaster of Paris casts, dental stone is actually a far less expensive casting material. Preparing the Footwear Im pression for Casting Most impressions need little if any preparation prior to casting with dental stone. One item that has received much attention in prior literature has been the instruction that the impressioned area should be cleared of any debris. It should be emphasized that in no instance should an attempt be made to remove any debris that is part of the impression or that was there at the time the impression was made. When footwear impressions are

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74

IB)

Figure 3.9 (continued) A pancake dental stone cast poured over an area filled with footwear impressions (B). made over rocks, sticks, or other debris, those items are pressed into the ground. Excellent transfer of detail is still very possible and probably exists in the areas immediately adjacent to the debris. Any attempt to try to remove such debris, particularly if it is imbedded in the impression, will almost certainly interfere with and ruin those adjacent detailed parts of the impression. Furthermore, because those items were between the shoe and the ground when the impression was made, their removal will in no way reveal any useful impression beneath them. If for some reason a loose leaf or twig has managed to have fallen into the impression after it was made and is clearly laying on top of the impression, then it can be carefully removed. It would seem, however, that this would be a less frequent occurrence. W hen Forms Are N ot U sed The older published articles on casting usually advised using a form to surround the impression. This was necessary because all casting was done with the softer plasters such as plaster of Paris. The form was required because the plaster cast had to have sufBcient thickness to permit reinforcement material to be placed within it. Footwear impressions that are cast with dental stone on level surfaces do not require a form. The casting material can be carefully poured into the impression until it overflows out of the impression. The end result will look somewhat like a pancake. Pancake casts are pictured in Figure 3.9B and C. It should be emphasized that the entire impressed area should be filled with casting material, particularly in deeper impressions. Significant detail is sometimes transferred from the midsole and the sides of the shoe to the sides of the impression. Figure 3.9D depicts the edge of a pancake cast of an impression which has retained detail from the side of the shoe. Once the impression has been filled, any additional material left in the bag can be slowly poured over the center of the cast to add thickness.

Casting Three-Dimensional Footwear Impressions

75

- âl^Ari'

»'■%

' >' TV'ÿ?,;;:.f ' .T:\'-yv/r / , "-". ':t'''.'.'-?

Figure

3 .9 (continued) T h e cast after clea n in g (C). T h e sid e of a p an cak e cast th at has retained detail m ade hy th e sid e of th e sh o e (D). N o te th e letterin g from th e brand n a m e and th e sid ew a ll stitc h in g in d icated hy th e arrow s.

U sing a Form Occasionally an impression may be on a slope or very uneven ground and require a form to control the flow of the casting material into the impression. In most of those instances, a form needs to be placed on one side of the impression only, positioned so the thickness builds up on that side first and directs the flow of the casting material back toward the

76

Footwear Impression Evidence, 2nd Edition

.Cm-

'Z?

. .'- / r li.'Æ '" '

Figure 3 .1 0

A partial form u sed to retain th e c a stin g m aterial over th e area o f a fo o tw ea r im p ression on a slig h t h ill. N o te h o w th e d en tal sto n e is poured o n to th e ground on th e up h ill sid e of th e im p ressio n , th u s a llo w in g th e dental sto n e to flo w in to th e im p ressio n . C a stin g m aterial sh ou ld n ev er be poured d irectly on th e im p ressio n .

impression. Form material can consist of premade forms, aluminum flashing, strips of chart board, or other suitable material. In those cases where a form must be used to contain the dental stone mixture, care should be taken in the placement of that form around the impression. At least 1 1/2 to 2 in. of space should be left between the edges of the actual footwear impression and the forming material. This will not only allow an area onto which the casting material can be poured, but it will also reduce the possibility of any distortion of the impression as the forming material is pressed into the ground. The form material itself should rest evenly on or in the ground so that the casting material will not seep or flow beneath it. It may be necessary to gently press the form material into the ground or, once the form is in place, fill any gaps that may remain between the form and the ground by placing some loose soil on the outside edges of the form. This will prevent the casting material from flowing beneath the form. Figure 3.10 illustrates the proper use of a partial form to contain the dental stone mixture in an impression that is on a slight slope. Re-enforcem ent Materials Re-enforcement materials, such as hard cloth wire or metal strips, were traditionally nec­ essary with plaster of Paris casts, to prevent them from breaking apart. On some occasions, persons trying to be resourceful used pieces of wood or wood sticks as re-enforcement materials. These absorbed the moisture from the drying cast, which caused the wood to swell, often contributing to or causing the cast to break. Dental stone and harder gypsum casting materials do not need any re-enforcement material and it should not be used.

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Fixatives and Release A gents A fixative is a material applied to a two- or three-dimensional impression, normally one which is of a fragile nature, for the purpose of preventing the impression from being altered or destroyed when it is cast. A release agent is a material applied to a three-dimensional impression to help prevent the soil or sand from adhering to the surface of the cast. Throughout the footwear literature, there have been numerous "recipes" recommended for preparing the impression with a release agent or a fixative prior to casting. For example, one article stated "If the surface containing the print consists of dust or sand, we should first apply a clear plastic or lacquer coating as a fixative using a spray applicator" (Samen, 1972). More than 30 years ago, the Ohio Law Enforcement Training Bulletin directed, "Spray ordinary white shellac, thinned with wood alcohol, into the print... Allow the first coat to harden ten to fifteen minutes ... Apply the second coat of shellac ..Allow to harden" (1959). Similarly, in 1951, the FBI Law Enforcement Bulletin recommended, "Impressions in sand, loose soil, and snow must be strengthened with a plastic spray, shellac, or other quick dry fixative... the spray should be directed over the impression rather than directly at it" (1951). More recently, Cassidy (1980) advocated a different technique for casting impressions in soil: The im pression sh ou ld n o w be covered w ith som e form o f release agent to allow the dirt to com e away from the cast w ith ease. Various agents from frying pan sprays to oil can be used for this purpose. However, from tests co n d u cted I have fou n d baby pow der to be an excellent release agent ...T he talc should be drifted over the im pression using a sm all atom izer or aerosol can plus a deflector card.

There also have been references which implied that release agents or fixatives are of no benefit or may possibly harm the impression: “The last item that can and should be eliminated from the casting kit are the fixative and release agents ... Damage to an impres­ sion is as likely to occur when the release and fixatives are used as when they are not” (Vandiver, 1980). The same author also states, “Tests without a fixative and with a clear fixative pointed out that neither ... helped produce a better cast” (Vandiver, 1981). There continues to be different views on whether or when a fixative or release agent of some form should be used. Many of the older recommended methods of “fixing” an impression, particularly those using shellacs, pump sprays, or hair sprays, were used in conjunction with the softer plaster of Paris and were intended, according to their authors’ directions, to build up a protective layer or shell over which the plaster was poured. This was undoubtedly being done, not because plaster would harm the impression, but rather to provide a protective layer which would prevent the detail from being lost when the soft plaster cast was later cleaned. This “protective layer” is not necessary with dental stone. Because it is not necessary, the applications of fixatives can only have the potential of harming the impression. Spraying any fixative over a dry impression, such as one in dry sand or loose, dry soil, has not demonstrated any increase on the retention of detail in a dental stone cast. It could, however, damage the impression if applied carelessly or incor­ rectly. Further, the improper use of fixatives or their use in excessive quantities might even obscure or fill in minute detail in the impression.

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Footwear Impression Evidence, 2nd Edition

Light talcs or very fine powders, so fine that they would not obscure even the most microscopic characteristics, are occasionally used as a release agent to provide a "cleaner" cast. A very light, indirect dusting of the talc or powder over the impression will prevent some of the soil from adhering to the cast. The dusting should be so light that it is hardly visible. The talc or powder should not be applied so heavily that it builds up on the surface of the impression. Casts of impressions that have been treated this way will release most, if not all, of the soil when they are lifted. Dental stone is sufficiently hard to allow it to be cleaned thoroughly without any loss of detail. The use of materials to fix or assist in releasing soil from the cast is a personal choice, not a requirement. M ixing D ental Stone at the Crime Scene As previously explained, because casting material mixed at a crime scene is hand mixed, it will not be mixed as efficiently as industrially mixed applications. The quick and thorough combination of the (1) pre-measured proper ratio of water and powder followed by (2) continuous mixing for 3 to 5 min, are the two most critical components. This is equally true, regardless of whether the materials are mixed in a plastic zip-lock bag or in a bucket. Reclosable bag method. Reclosable plastic bags, with zipper locks, are recommended as a means of storing premeasured amounts of dental stone. A zip-lock bag measuring approximately 8 x 12-in. can easily store 2 lb of dental stone powder. When the time comes to make a cast, the zip-lock bag containing the dental stone powder can also be used as the mixing container. With premeasured zip-lock bags on hand, casting impressions at the crime scene will involve only the addition of the proper quantity of water. The bag can be used to both mix and pour the dental stone mixture. Those who have tried this method have found it to be a quick, clean, and convenient method of casting. Dental stone, like other gypsum materials, is usually sold in bulk quantities of 25, 50, or 100 lb. Carrying containers of this size around at a crime scene is often not practical. The casting powder can be quickly divided into 2-lb portions in 8" x 12" plastic zip-lock bags. The weighing of those portions should be reasonably accurate. Once the bags are filled, they can be laid on one side and flattened to remove the excess air and then be zipped closed. The bags will keep the casting material dry and will be convenient to use when needed. It is both an advantage and is recommended to prepare these pre-weighed bags of dental stone powder in advance. Then, when the time comes to prepare a cast at a crime scene, the zip-lock bags of dental stone are ready and convenient. Dental stones require about 5 oz of water per pound, depending on its consistency. Harder stones will require even less water. As an example, Castone^ dental stone has a consistency listed on its container as 30 ml/cc water per 100 g powder. Converted, this would require 2 lbs of Castone dental stone to 9.2 oz of water. Since the exact W:P ratio will vary slightly from one consistency or brand of dental stone to another, the pre-measured amounts of water to powder must be computed for the specific product you are using. An easy way to compute the amount of water to be combined with a 2-lb portion of dental stone casting powder is to multiply the consistency by a factor of .306729.^

® Dentsply International, York, PA. ^ For 2 1/2 lb, the multiplication factor would be .383411. So, 2 1/2 lb of dental stone powder, having a consistency of 30, would compute as 30 x .383411 = 11.5 oz of water.

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For two p o u n d s o f dental ston e pow der having a con sisten cy o f 30: 30 X .306729 = 9.20 oz o f water.

For convenient reference, the table below lists the quantity of water, in ounces, rounded off to the next highest 1/10th oz, for 2-lb portions of casting powder, for various different consistencies. For instance, if you purchased Brand X dental stone and on its container it stated its consistency as 35 parts water (35 ml/cc) per 100 parts powder (100 g), then, for a 2-lb portion of powder, you would look at the below table and determine that 10.8 oz of water was needed. It is important to note that a very slight additional amount of water may be needed to improve the pourability of the material. A pre-marked water container should be used to ensure the correct amount of water is being used. C on sisten cy

Fluid o u n ces w ater ad d ed to 2-lb pow der

26 30 35 40 45 50 55 60

8 9.2 10.8

12.3 13.8 15.4 16.9 18.4

Once the proper ratio is determined, mixing should proceed as follows. Add the pre­ measured water to the zip-lock bag and close the top. Immediately mix the casting material by massaging and mixing through the bag continuously for 3 min. Make sure that all of the material in the corners of the bag is mixed. The proper viscosity should be that of pancake batter or thick cream. If the proper consistency (W:P ratio) has been used, the viscosity should automatically be correct. When the water and dental stone are completely mixed for 3 min, the casting material is ready to be poured. This is easily accomplished by simply unzipping the bag, holding it low and next to the edge of the impression, and carefully pouring the material onto the ground, directing its flow into the impression. If the mixture is too thick, or, if after the cast is poured, watering out occurs, either the W:P ratio is off or the mixture was not mixed enough. The zip-lock bag method has been very popular and user-friendly. It provides a con­ venient, clean, and rapid way of preparing a quality cast. Although it involves adding the water to the powder, instead of the opposite, using proper pre-measured amounts and mixing them immediately is acceptable. If more than one cast is being prepared, the person in charge of doing the casting can solicit the help of another individual to assist in the mixing portion of this process. If the impressions are extremely large and deep, it may be more desirable to mix a larger amount of dental stone in a small bucket or rubber container rather than using several bags.

It is important to note here that, although this amount of water is the correct ratio, the mixture is slightly thick and may he difficult to pour. An extra 1/2 to 1 oz of water (hut no more) may he needed for easier pouring and is perhaps necessary for pouring the materials quickly.

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Mixing dental stone in a bucket. If a large quantity of dental stone is to be mixed at one time, first make an assessment of the quantity of material needed. For instance, if there are 6 full footwear impressions, you can figure on 12 lb of dental stone, and the appropriate ratio of water. In the example cited above for Castone, 2 lb required 9.2 oz of water, so 12 lb of dental stone would require 55.2 oz of water. Again, it may be necessary to increase the water quantity very slightly, as previously noted, to improve the pouring qualities. The water should first be added to a bucket. The dental stone should be sifted into the water and continuously stirred for 3 to 5 min. The combination of a portable electric drill and a paint mixer attachment would provide an excellent mixing aid. Once mixed, the material can now be poured into the impressioned area. As previously mentioned, mixing via the bag and bucket methods combined with air drying will not result in casts having the compressive strength that is published on the container of a particular casting material. Should you begin with a product with a published dry compressive strength of 3,000 psi, you will wind up with half ( 1,500 psi) or less which is too soft to clean without risking loss of detail. By beginning with a product having a dry compressive strength close to 8,000 psi or higher, the resultant hardness will be more than sufficient. Pouring the Casting Material Whether a form is used or not and whether the casting material is mixed in zip-lock bags or in buckets, the procedure and precautions for pouring the casting material into the impressioned area are the same. Casting material has sufficient weight and volume to easily erode and destroy valuable detail if it is carelessly poured directly onto the impression. This is especially true in the case of fragile soil and sand impressions. When pouring the casting material from the zip-lock bags, the bag should be placed next to the impression so that the casting material does not cascade onto the impression but instead flows onto the adjacent ground and then into the impression. When pouring the casting materials from a bucket, the bucket should be held close to the ground and the casting material should be poured onto the ground or a spoon or flat stick next to the impression in a way so that the casting material would not directly strike the impression but would naturally flow toward and into the impression (Figure 3.10). Again, it should be emphasized that the entire impression must be filled with casting material until it has overflowed. If the pourability of the dental stone appears ideal when the first cast is poured, but too thick by the time the last cast is poured, this is due to insufficient mixing or an improper W:P ratio. Often in this same situation, the cast will ‘‘water out”, i.e., water will work its way to the surface of the poured cast as it hardens. Making sure the dental stone and water proportions are correct and the materials are thoroughly mixed before pouring each impression should eliminate these problems. When the cast sets and loses it gloss, but before the cast completely hardens, it is possible to scratch the date, your initials, and any other desired information onto the top of it. The cast should then be left undisturbed for at least 20 to 30 min in warm weather. If the temperature is cold, the cast should be allowed to sit longer. Many casts have been destroyed or damaged because they were lifted too soon. When the time has come to lift the cast, care should be taken so as not to damage it. If the cast has been poured in sand

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or loose soil, it should lift very easily because air can get beneath it. Casts poured in heavier soils, such as mud or clay, may require more careful treatment and sometimes even slight excavation to assist their removal. Trying to pry a thin cast out of heavy soil by pulling on its edge may cause it to break.

A fter th e C ast is P ou red The reaction that takes place upon combining and mixing water and a gypsum product requires time for completion. During that time, there are a number of stages in the setting process of the cast, which are defined below: Mixing time: The time from the combination of the powder and water until mixing is complete. Working time: The time available to use the mix, such as the time after mixing during which the cast may be poured, before it sets. Setting time: The time that elapses from the time of mixing to the time of initial hardening. Loss of gloss: The point during the reaction at which sufficient excess water is consumed in the reaction so that the mixture loses its gloss. Ready for use: A subjective amount of time at which the cast may be safely handled (normally 20 to 30 min in average temperatures). The ready for use time is the time at which the cast can be lifted carefully from the impression and then dried. It does not imply that the cast is totally dried or ready for cleaning.

How Casts Dry Plasters, in general, require about 18.6 parts water per 100 parts plaster by weight for complete hydration in the setting process.” Since it is necessary to have more water in order to mix the powder and water in a slurry, greater quantities of water must be used. Later, after the mixture has been poured and set, any water above the 18.6 parts is excess and must be removed by drying. To remove the ‘"/rcc” water from the cast requires energy. This energy can be provided through evaporation or through the use of industrial dryers. During drying, water from the interior of the cast moves to the surface to replace evaporating moisture. The total compressive strength of a cast only increases only slightly until 93% of the excess water has been re m o v e d .F o r example, an industrially mixed gypsum cement having a normal consistency of 38 may have a final optimal dry compressive strength of 7,000 psi, but may only have a wet compressive strength of 3,500 psi one hour after setting. This is because the cast has not yet totally dried. If the cast was mixed by hand, its psi after one hour will be considerably less. This is highly significant because it illustrates the importance of completely drying a cast before attempting to clean it.

United States Gypsum Company, Drying Plaster Casts, Bulletin No. IG502, Chicago, IL, February 1996. United States Gypsum Company, Bulletin No. IG502, Chicago, IL, February 1996.

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A llow ing Crime Scene Casts to Air Dry Once removed, casts poured at crime scenes will usually have some quantity of wet soil or sand that sticks to and possibly covers the impression side of the cast. No attempts should be made to clean the cast at this point. Although the dental stone has set and appears to be hard and dry to the touch, it is not completely dry nor hardened. The cast should be allowed to air dry at room temperature for at least 48 hours. The cast should be positioned so air can circulate around and beneath it. After the cast is/t///y dried, it is then ready for cleaning by the examiner, or it can be safely placed in a sturdy paper hag for shipping to a laboratory or for storing. Casts should never be placed or stored in plastic bags for they may still contain some moisture. If a cast still containing moisture is placed in a plastic bag, the bag will trap the moisture escaping from the inside of the cast and it will re-condense on the outside of the cast. Underwater Casting Impressions that are only partially underwater, or that simply have standing water in them, can be cast with the regular casting procedure. Pouring the dental stone mixture into the impression will simply displace the water in the impression. Impressions that are totally underwater can also be cast. The following instructions should be followed: Do not attempt to drain away any of the water over the impression area. This is not necessary and will only risk disturbing the impression. If any leaves or twigs are floating over the impression, you may safely remove them, but do not attempt to remove any debris if it is part of or is touching the impression. Movement of any type in the water risks disturbing the entire impression. Carefully place a full casting frame around the impression that is large enough to allow a minimum of 2 in. of extra space on all sides of the impression. This will prevent the impression from being distorted or disturbed when the form is pressed in to place. The frame should be high enough so that its sides will rise above the water line, permitting it to be put in place without having to reach into the water. A disposable frame made from chart board or cardboard, or a bucket with the bottom cut out, can be used for this purpose. Lightly sift the dental stone powder over the areas of the impression that are underwater until 1 in. of the casting powder covers that area. Prepare a mixture of dental stone in a separate container in the same manner as you would for dry impressions. Prepare enough so that it will fill the framed area with a 2-in. thickness of dental stone. Add the mixture to the framed impression by carefully pouring it into that area, allowing it to settle through the water and onto the impression. Make sure the entire bottom surface is eventually covered with the casting material. The cast should be allowed to set for at least 60 min. The water will act as a release agent, as any detail will be visable when the cast is lifted. Cleaning Stone Casts An important and significant quality of dental stone casting material is that it can be cleaned without loss of detail. Because the casts should air dry for 48 hours before cleaning, the cleaning is normally performed in the laboratory by the examiner who will be exam­ ining the cast. Newly poured casts should never be cleaned at the scene because they are

Casting Three-Dimensional Footwear Impressions

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not totally dried throughout and will therefore not have reached their maximum hardness. Most casts require little cleaning. Those having loose soil or sand adhering to them can be cleaned by rinsing the cast surface with water assisted by if needed, the use of a soft brush. If the casts are covered with heavy clay soil, the method below, suggested by Brennan, works well. Brennan reports that dental stone and die stone are best cleaned in a saturated solution of potassium sulfate for approximately 1 hour.‘^ During this procedure, degassing of the cast will take place resulting in streams of air bubbles being released from within the cast. This assists in loosening clinging soil. This procedure will not work with the softer plasters because immersion of the softer plaster casts in the solution will further soften them and result in erosion and loss of detail. In fact, placing a soft plaster of Paris cast in water will likely dissolve it. A good demonstration of this is to make a plaster of Paris cast and a dental stone cast. After the casts have dried for 48 hours, place each cast in a separate bucket of water overnight. The plaster cast will be ruined, whereas the dental stone cast should be unaffected. To clean a cast containing heavy and difficult to remove soil, a container large enough to submerge the cast is needed, along with an ample supply of potassium sulfate. A saturated potassium sulfate solution should be prepared in the container. The cast should be carefully submerged in the solution at room temperature and allowed to sit for approximately 1 hour. On placing the cast in the solution, streams of air bubbles will be released from within the cast. After the soil has been softened and loosened, a soft bristled brush can be used to help remove that soil from the surface of the cast. Brushing can be done with the cast still submerged in the solution. The cast should then be thoroughly rinsed with water and allowed to drain and air dry. Failure to thoroughly rinse the cast will result in a white residue of potassium sulfate on the surface when it dries. Photographing the Cast After any cast has been cleaned, and prior to examination, it should be photographed with a scale to capture the maximum amount of detail. To photograph the cast, use a fine­ grained, color or black-and-white film having an ISO of 400. In a darkened room, use a strong oblique light source which is capable of directing a focused beam of light from several feet away. This assures that the lighting across the surface of the cast will be uniform. The camera’s f-stop should be set to give the maximum depth of field. The use of fill lighting to lighten the shadowed areas is usually beneficial. Photographs of the cast can serve many purposes. The photographs will provide a permanent record of the cast. Notations can be made on them during the examination, and they can be used later for presentation in court. Shipping and Storing Casts Although dental stone casts are very durable, they are still capable of being broken and therefore will require reasonable common sense and attention during storage and subse­ quent shipment. The casts should never he shipped when wet. After thorough drying, they can be placed in separate paper bags. They should never be sealed in plastic wrapping. Brennan, J., Dental Stones for Casting Depressed Shoemarks and Tyremarks, 1983.

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Figure 3.11

An im p ressio n in sn o w ¡A), w h ic h is h ig h lig h te d by spraying th e im p ressio n at an angle w ith Sn ow Print W ax (B) and th en co a ted w ith th ree or four h eavy sprays o f S n ow Print Wax (C). T h e im p ressio n is th en filled w ith a c o o le d m ix tu re o f d en tal sto n e (D).

When shipping casts, dry packing material which is sufficiently thick should be used to separate all surfaces of each cast from the others and to afford the necessary protection from breakage. The container should be marked "fragile".

Casting Footwear Impressions In Snow B ackground In many areas of the country, snow is on the ground for a substantial number of days each year. Footwear impressions in snow can provide investigators with excellent information regarding the number of suspects, the approximate time of the crime, the point of entry and exit, and the direction in which the suspect left the crime scene. As with other footwear impressions, examination quality photographs of impressions in snow should be taken before casts are made. Additional examination quality photographs, with the added high­ lights provided with a light application of Snow Print Wax or other colored spray aerosols, will provide further detail. Figure 3.1 lA shows an examination quality photograph of an impression in snow. The contrast is very poor because of the white color of snow and the translucent nature of it. Figure 3.1 IB shows that same impression after it has been high­ lighted with a light spray of red Snow Print Wax. Older methods of casting footwear impressions in snow involved tedious procedures with very limited results. For instance, a 1972 article recommended the following method: Shake or dust lightly a thin layer o f talc over the im pressioned area, follow ed by a layer o f shellac or clear lacquer. This step is repeated a m in im u m o f three tim es, allow in g several m inutes betw een each application ... O n ce the base is dry, shake or dust three thin layers o f dry plaster, alternating w ith a water spray over the original crust. (Sam en, 1972).

Casting Three-Dimensional Footwear Impressions

Figure 3.11

85

(B)

(continued)

Years before that, the FBI Law Enforcement Bulletin advised that “a fine layer of talcum powder sprinkled over the surface of a snow impression will serve to insulate the snow from the heat of the setting plaster” (Anonymous, 1951). “Whenever practical, crime scene footwear impressions in snow should be photo­ graphed and then cast to preserve their evidentiary value” (Nause, 1992). Snow Print Wax Snow Print Wax offers a quick and easy method for casting footwear impressions in snow (Carlsson, 1982; Ojena, 1984; Kenny, 1994). This product, originally used in Sweden, was introduced in the U.S. around 1983. It is an aerosol spray wax, bright red in color. When it is applied to the impression, it forms a wax shell and will preserve the detail in the snow impression. The wax shell is then filled with cooled dental stone to ensure stability and a solid structure for the wax shell so that it may be lifted from the ground. This product comes in an aerosol can with step-by-step instructions. It should not be confused with the white snow wax spray used for Christmas decorations, for that type of decorative wax will melt and destroy snow impressions. Red Snow Print Wax is best utilized in the retrieval of footwear impressions as follows: First, always take general scene and examination quality photographs. Snow impres­ sions will have a variety of depths, so it is important to assure that the ruler is on the same plane as the impression (Figure 3.1 lA). Next, using Snow Print Wax, lightly spray the footwear impression at an angle so as to highlight the raised areas of the impression, but not to entirely cover the impression. Be careful not to hold the can so close to the impression that the blast of the aerosol may damage the impression. After highlighting the features of the impression, rephotograph it in the same manner as before as shown in Figure 3.1 IB. This technique is very quick and simple and can be used to add contrast to impressions as well as show their location in the general scene photographs.

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Footwear Impression Evidence, 2nd Edition

(C) 3 .1 1 (continued)

Once impressions have been sprayed with Snow Print Wax or other colored sprays, they will absorb additional heat from the sun which will cause the impression to melt rapidly. This is particularly true if they are in direct sunlight. For that reason, any time a snow impression is sprayed in sun or even on a bright cloudy day, the sun's rays should be shielded from striking the impression after it is highlighted. Surprisingly, melting will occur even if the outside temperatures are extremely cold. After the highlighted impressions have been photographed, continue to carefully spray layers of Snow Print Wax over the impression. Add a total of three generous layers of Snow Print Wax to the impression, allowing the wax to dry for 1 to 2 minutes between each layer. Attempt to evenly and thoroughly cover the entire impression, as shown in Figure 3.11C. Include spraying areas on the side of the impression as well. If any areas are not completely sealed with the wax, the dental stone that is later added may seep through the holes and undercut the impression. This could harm the impression by allowing the dental stone to flow and harden beneath the impression. It takes at least three, and sometimes four, applications of Snow Print Wax to provide a sufficiently thick coat over the impression. The coating of wax as viewed from the top will not reveal any detail of the shoe impression. The detailed portion of the wax shell is facing down against the snow impression. The detail will be visible when the cast is later lifted and turned over. When you are satisfied that the impression has been completely covered, allow the wax shell to dry for about 10 min. During this time, prepare a 2-lb mixture of dental stone. Since heat is released during this process, using cold water or substituting some snow for the water in the mixture will help reduce the heat emitted by the dental stone mixture. The consistency of the dental stone mixture should have sufficient viscosity so it does not break through the thin areas of the wax shell. Some persons recommend waiting 2 to 3 minutes, after mixing but before pouring the dental stone, to reduce the time the warm material will be in the wax shell before it sets. The dental stone should be carefully poured into the impression over the wax shell (Figure 3.1 ID).

Casting Three-Dimensional Footwear Impressions

Figure 3 .11

87

(continued)

If the outside temperature is well below freezing, potassium sulfate can be added to the water used to mix the dental stone. A 5% solution is adequate. A 5% solution can be mixed by dissolving 50 g of potassium sulfate in water and then increasing the volume of water to 1 1. The use of potassium sulfate in the water will both accelerate the setting of the cast and will reduce the freezing point of the solution. This is essential if a cast is being poured in extremely cold conditions. An examiner from Alaska reports that if potassium sulfate is not used, the cast may freeze before it has time to set.'"* Allow the cast to sit undisturbed for at least 60 min or longer, if necessary, to provide adequate time for it to set in the colder temperatures. The cast may be covered with a box or section of newspaper to help it set more quickly in the cold weather. When the cast is removed, it must be handled carefully to avoid touching the bottom surface which contains the soft wax shell containing the detail of the impression. The wax shell will remain soft and must be treated accordingly. Figure 3.12 shows the finished red wax cast. Attention should be directed toward the storage of Snow Print Wax in cold weather. The label on the Snow Print Wax can states that the can must be at room temperature or it will have insufficient pressure. It also states that the can may be placed in warm water to restore the pressure. Therefore, if the cans are subjected to freezing conditions, such as would occur if they were stored in a car during a cold winter, they may not be readily usable at a crime scene. It may be wise to keep only a portion of the supply of this product inside the crime scene vehicle in cold weather, with the remainder being stored safely indoors where it will always remain at room temperature. That way, if there is any problem, the material that has been stored in a warm environment would be available. Beheim, C., Alaska State Crime Laboratory, personal communication.

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Figure 3 .1 2

T h e ca st m ade u sin g th e S n o w Print Wax procedure sh o w n in Figure 3 .1 1 .

Casts made using Snow Print Wax are very fragile. The wax shell that contains the detail is soft and can be rubbed away through contact with the hands or other careless handling. For that reason, nothing should be allowed to touch the impression side of the cast. Snow Print Wax casts should be photographed to assure that a record of their detail is maintained. Caution should also be exercised with casts at the crime scene. If a Snow Print Wax cast is allowed to sit in the sun, the wax shell may melt. Two newly made casts were lifted and then left in the sun for about 10 min. Even though the outside temperature was a cool 52°F, the intense rays of the sun began to melt both casts, one of which is pictured in Figure 3.13. This can be avoided simply through careful storage and handling of the casts. The wax shell will not melt at normal indoor temperatures. Sulfur Casting Casting footwear impressions in snow with sulfur has been practiced in many countries for years. Some of the difficulties encountered with this technique are discussed by Carlsson and Maehly (1976): At present, the recom m ended procedure for securing im pressions in sn ow — at least in Scandinavia — is casting w ith sulfur. T his must be d o n e slightly above the m elting p o in t o f Sulphur ( 1 13°C) and is tricky to carry out. If the tem perature is too high, m eltin g will occur and valuable detail will be destroyed. Even under perfect con d itio n s, so m e m eltin g takes place and gives a cast w ith a som ew hat porous and unsharp surface. Also, in loose pow dery snow , the sulfur so m etim es runs through the trail and collects under its surface.

Other examiners appear to have experienced no problems with this technique: T he traditional m ethod o f casting sn ow im pressions is with m olten sulfur. The sulfur in pow der form is heated to approxim ately 115°C and then the m olten mass is poured into

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Figure 3 .1 3

A cast m ade w ith S n ow Print Wax th at w as a llo w e d to sit in th e su n . N o te th e m e ltin g of th e w ax sh ell, w h ich form ed a glaze. the snow im pression w here it solid ifies, accurately capturing the im pression's detail (Cassidy, 1980).

In reporting and comparing various casting methods in snow of various textures and moisture content and at various temperatures, it was reported ... prill sulphur is recom m ended for casting footwear im pressions in sn ow before other m ethods. The use o f Snow Print Wax in con ju n ction w ith prill sulphur is a good technique; however, com parable results can be achieved w ith prill sulphur alone (N ause, 1992).

There are many people who have had good success casting footwear impressions in snow with sulfur, though personally I have had only limited success with sulfur casting. 1 have been able to recover size and design detail in all cases, but fine detail in only a few. All of the persons I know who have claimed to be satisfied with sulfur casting reside in

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very cold climates. Their success with sulfur casting appears to be a result of the type of snow and conditions of that colder climate. Nause summarized his experiences by stating: Im pressions in pow dery sn o w displaying poor pattern detail w ill n ot cast w e l l .... Im pres­ sions suitable for casting w ill usually be form ed w hen the tem peratures are just below freezing, allow in g the sn ow to com press and record excellent pattern detail (N ause, 1992).

In other words, if the texture of the snow crystals is coarse, it wUl not allow for finer detail in the impression to be retained. Instead, the sulphur will reproduce the coarse snow texture. Casting with melted sulfur involves (1) the careful melting of a quantity of sulfur, (2) the re-cooling of the melted sulfur to a temperature just above its crystallization point, and (3) the rapid pouring of that sulfur into the snow impression. As the sulfur comes in contact with the snow, it recrystallizes immediately, retaining the detail of the impression. To make a sulfur cast, the following materials will be needed: 1. A quantity of crystalline sulfur. Approximately 5 lb of powdered sulfur will be needed

per impressioQ. Prill sulfur, which has been melted and resolidified, is reportedly better. 2. An electric heating plate or propane burner. The heating plate offers much safer and more uniform heat than a propane burner; however, if the casts need to be made far from a power source, a propane gas burner must be used. Appropriate cautions must be used whenever heating sulfur with an open flame heat source. 3. A 1 qt aluminum pot with a handle and a lid. This will be used to contain the sulflir. The lid and handle will come in handy if you need to transport the hot molten sulfur some distance from the heating source to the impression. 4. A large metal spoon to stir the sulfur. 5. Some strips of chart board, wood, or metal flashing which can be used to create a pouring channel. To make a sulfur cast of an impression, a channel must be prepared which will direct the flow of the molten sulfur into the footwear impression. To do this, build up a portion of the snow to a level that is to the side and higher than the impressiou. This, either by itself or with the assistance of some form material, will serve to direct the sulfur into the impression. No other preparation of the impression is needed (Figure 3.14B). Fill the aluminum pot with sulfur. Place the pot on the heating plate or burner and turn the heat on a low to medium setting. Sulfur melts at around 115°C; however, if the sulfur should reach 170°C, the sulfur will irreversibly change into a syrupy, thick, brown mass and will be permanently ruined. For that reason, the sulfur must be heated very slowly. Increase the temperature a little at a time while stirring constantly. As the sulfur begins to melt, it will take up less room in the container and additional sulfur can be added until eventually the proper quantity of melted sulfur fits into the melting pot. About 5 lb of sulfur is required for one impression. Continually stir the sulfur throughout this entire process to avoid the sulfur on the bottom from getting too hot. Nause, L., Casting footwear impression in snow: Snowprint wax vs. prill sulphur, R C M P G a z e t t e , 54(12), 1992.

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(A)

(B)

Figure 3.14 T h e procedure for m a k in g a su lfu r ca st in v o lv e s (A) m e ltin g th e sulfur, (B) preparing a ch a n n el to direct th e su lfu r in to th e im p ression , and (C) p ou rin g th e su lfu r in to th e c h a n n el, a llo w in g it to flo w in to th e im p ressio n area. When all of the sulfur has been melted, as shown in Figure 3.14A, the heating source can be removed or turned off. The stirring must continue to ensure that a uniform temperature remains throughout the liquid sulfur. When the uniform temperature of the

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(C)

Figure 3.14

(continued)

sulfur drops to within a few degrees of the crystalline point of 115°C, the sulfur will begin to crystallize around the edges and on the surface. Continue stirring slowly until the crystals will no longer dissolve, even during the stirring process. At this point, the sulfur is very close to 115X and is ready for pouring into the impression. A thermometer with an appropriate scale can be used during this entire process to monitor the temperature, if desired, but this is not necessary. Pour the entire amount of sulfur into the prepared channel so that it will be directed down the channel and into the impression. The pouring process should be done quickly and without hesitation. The sulfur will crystallize immediately as it makes contact with the surface of the impression and will take on the detail in the impression (Figure 3.14C ). Although the re-crystallized sulfur will appear hard, the inner areas of the sulfur cast will remain hot and soft for some time. The cast must therefore be allowed to sit undis­ turbed for at least 30 min until it is thoroughly cooled. Sulfur casts are extremely fragile and brittle, so extreme care must be exercised when lifting and handling the cast. The sulfur cast will provide a representation of the detail in the snow impression, but, as previously mentioned, will also reproduce any texture pattern present in the snow. This is shown in Figure 3.15.

Paraffin Casting Paraffin wax can also be used to cast a footwear impression in snow; however, it is not a recommended material. The paraffin must be slowly melted and will require at least 1 1/2 lb for a footwear impression. A black or colored wax crayon can be added to the paraffin to provide color to the cast and provide better contrast. The paraffin must be melted slowly for safety reasons, since rapid melting of paraffin can result in it popping or ’’exploding". The paraffin can be melted in an aluminum pot on a heating plate (Figure 3.16A). A

Casting Three-Dimensional Footwear Impressions

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Figure 3.15

A su lfu r cast o b ta in ed u sin g th e procedure sh o w n in Figure 3 .1 4 . N o te th e cast reflects th e tex tu re of th e sn ow .

channel must be prepared, like that for the sulfur cast, to guide the melted paraffin into the impression (Figure 3.16B). When the paraffin completely melts, the heat should be turned off and the paraffin should be stirred occasionally as it cools back down to its melting point. As the cooling paraffin approaches that temperature, a wax skin will begin forming on the surface, which will re-dissolve with additional stirring. When it cools a little more, it will be harder for the skin to dissolve. The paraffin is then ready to be poured into the channel. Up to this point, the time required and general procedures for melting the paraffin are very similar to that of sulfur. When the paraffin flows into the impression, it will form a shell where it makes contact with the colder snow impression. The rapid cooling can cause air entrapment between the wax and the impression. This trapped air can interfere with the detail in the impression, and an accurate recording will not be reproduced in those areas. In addition, the remaining paraffin in the interior parts of the cast that are not in direct contact with the snow will remain very hot. The hot paraffin will keep the hardened portion next to the impression soft, which, combined with the weight of the paraffin, can result in distortion, sagging, twisting, and bending of the cast. Both the air entrapment and twisting can be seen in Figure 3.17. For these reasons, and due to the length of the procedure, paraffin is not recommended as a casting material for snow impressions.

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(A)

(B|

Figure 3.16

T h e procedure for m a k in g a paraffin ca st in v o lv e s (A) m e ltin g th e paraffin and (B) pouring it in to a prepared ch a n n el th at d irects th e paraffin in to th e im p ressio n .

Auto Paint Primer Spray with Dental Stone Another method of highlighting and casting snow impressions has been recommended by some (Johnson, 1983; Wolfe and Beheim, 1989 and 1994). This technique involves the use of gray auto spray primer that conies in aerosol cans and is used to prime cars before

Casting Three-Dimensional Footwear Impressions

95

|AI

' -'r-'V V", -’ > V' ' : î,^I^'-i'>k'' .

IB)

F ig u r e 3 .1 7 A paraffin cast. N o te th e tw is tin g of th e ca st (A), w h ich has resu lted from th e sagging of th e w arm , so ft paraffin under its o w n w e ig h t as th e sn o w m e lts b en eath it. A lso n o te th e spaces form ed from trapped air (B).

painting. It is available in any store carrying basic auto supplies. As cautioned previously, the application of color sprays, including the gray primer, to the impression s surface, if in direct sunlight, will cause the impression to melt rapidly. This will occur even in sub-zero temperatures. To avoid this, a piece of chart board or another makeshift opaque sun screen should be placed in a position to shield the impression from the sun prior to using this method. The impression is first lightly sprayed with the gray primer to highlight it in the same way previously demonstrated with the red Snow Print Wax. At that point, additional examination quality photographs of the highlighted impression should be taken. In cli­ mates where it snows and the air temperature is at or just below freezing, I would not recommend the primer be used to coat it in the same manner as Snow Print Wax. However,

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Figure 3.18

A gray a u to body p rim er/co o led d en ta l sto n e ca st (cou rtesy of A lask a S c ie n tific C rim e D e te c tio n Laboratory).

examiners in colder climates (Wolfe and Beheim, 1994) recommend spraying the snow impression with several thin coats of gray Krylon‘^ primer to form a thin shell to accept the dental stone. The impression should now be filled with a mixture of dental stone prepared with a 5% solution of potassium sulfate in water. Then add snow to the water to make a slurry of icy water. Use this icy potassium sulfate solution to mix with the dental stone. As previously stated, the potassium sulfate mixture can reduce the freezing point considerably, thus allowing the cast to set before freezing occurs. The finished cast will have the color of the gray primer. A cast obtained with this procedure is provided in Figure 3.18.

Summary of Snow Casting Snow and snow crystalline structure vary because of differences in temperatures and other variables that naturally occur over different climatic conditions. Snow can be dry or wet, powdered or well packed, fresh or remelted. The choice of whether to use Snow Print Wax, sulphur, or gray primer, combined with cooled dental stone for casting snow impressions should be based on one's personal experience with each method, as well as the snow conditions and temperatures existing at a particular crime scene.

The Importance of Casting all Three-Dimensional Impressions The question is often asked as to whether it is necessary to cast every footwear impression located at the crime scene. The answer is yes, and there are many good arguments which support casting every impression. A partial impression, due to the soil makeup and the manner in which the soil received the detail of the footwear, may leave a more valuable Krylon, Sherwin-Williams, Solon, OH.

Casting Three-Dimensional Footwear Impressions

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The Importance of Casting all Three-Dimensional Impressions The question is often asked as to whether it is necessary to cast every footwear impression located at the crime scene. The answer is yes, and there are many good arguments which support casting every impression. A partial impression, due to the soil makeup and the manner in which the soil received the detail of the footwear, may leave a more valuable and detailed impression than one that includes the whole surface of the shoe. It is not possible when processing a crime scene to see all of the detail present in each impression, nor, without the shoes, would it be possible to recognize the true value of that detail. This would be guesswork at best. If a crime scene technician were confronted with 10 latent fingerprints at a scene, he or she might surmise that some of those impressions may have sufficient detail to effect an identification and others may not. She or he would know that the best place to determine that is in the laboratory and not at the scene. The technician would not lift only 5 of those 10 impressions and leave the other 5 at the crime scene because of the real possibility that the most valuable impression might be left behind and lost. The same consideration should apply to casting footwear impression evidence. For each impression that could be cast, but is not, whether a partial or full impression, the potential for losing an identification or otherwise meaningful conclusion exists. There maybe a few excuses why it is not possible or reasonable to cast all of the footwear impressions at a scene, hut few good reasons. Unless adverse weather conditions prevent it, all footwear impressions should be both photographed and cast. In actual practice, not much more time or effort is involved in casting 10 impressions than in casting 1 or 2, providing you are properly prepared. Most shoes, particularly athletic shoes and hiking boots, have synthetic outsoles and have sufficient acquired random characteristics such as cuts and nicks on them which serve to make them unique and identifiable. The chances of such shoes leaving three-dimensional impressions that retain sufficient detail to be suitable for identification are excellent. Evidence with the potential to provide such important information should never be left at the crime scene. All impressions, whether in soil, sand, snow, or even underwater, are suitable for casting. Casts should always be made of three-dimensional impressions. Evidence that is left at the crime scene is lost forever!

Treatm ent of T w o-D im ensional Footwear Im pressions

4

Lifting Two-Dimensional Footwear Impressions Two-dimensionaJ footwear impressions can be composed of virtually any material a shoe tracks through, ranging from blood to dust to mud. The impressions range from very light to heavy depositions of that material onto a variety of substrates. In some cases, the materials will contrast very well with the substrate onto which they are tracked, while in other instances the contrast may be so faint as to go unnoticed. Lifting a footwear impression is a way of transferring a two-dimensional impression from its original surface to a surface that will provide better contrast. The lift provides improved visibility of the impression's features through improved contrast, and also pro­ vides a means of recovering and transporting the impression to the laboratory for exam­ ination. In addition, certain lifting procedures can actually be used to locate latent footwear impressions that would otherwise go undetected. Some impressions will lift easily and with much detail, whereas other impressions may only lift partially, or not at all. As a result, there is sometimes a risk that impressions may be destroyed during attempts to lift them. Visible footwear impressions on items that can be removed from the scene such as those on paper or broken glass should not be lifted at the scene. They should be transported carefully to the laboratory where forensic photo­ graphs may be taken and where there will be more time and resources to carefully study and determine whether lifting or other methods should be used to enhance the impressions. Footwear impressions that are visible should usually be lifted only when the item bearing the impression cannot be removed from the scene without risking damage to the impression. A common example of impressions that cannot be removed and must be treated at the scene are those found on bank counters. One of the problems crime scene officers often encounter is the unavailability of adequate footwear impression lifting materials. As a result, the crime scene officer often must resort to makeshift lifting materials or to materials primarily developed for lifting powdered latent fingerprints. Whereas some of these makeshift materials are used success­ fully for lifting fingerprints, they are not always as successful or adequate for lifting footwear impressions. For example, clear 2-in. adhesive lifting tape, routinely and successfully used

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to transfer powdered fingerprints to white cards, is more clumsy and difficult to use for the much larger footwear impressions (Figure 4.15). Another problem has been the false assumption that any lifting material will lift any footwear impression. This misunderstanding of the lifting process has resulted in countless impressions lost or damaged during those attempts. There are many different types of lifting materials and techniques and not all are best suited for all types of impressions. Products and materials specifically developed for lifting footwear impressions are available through forensic suppliers. These include electrostatic lifting devices, footprint-sized gel­ atin and adhesive lifting materials, and silicone casting materials. Footwear impression lifting materials which are not recommended are those of the makeshift variety and include other adhesive coated papers such as shelf or contact paper, clear and colored tapes of all types and sizes, and carbon paper. These should not be used. The many materials through which a shoe may track and then redeposit, in the form of an impression, combined with the many surfaces on which a shoe can impress those materials, results in a large number of impression/surface combinations. Deposited mate­ rials will adhere to different surfaces in a variety of ways. A dry origin residue impression will not bond well to a smooth, clean, dry surface and therefore will easily lift from that surface. Add moisture to the residue or surface, and the degree of bonding will increase. Successful lifting of the impression then becomes more difficult. Further, impressions that result when a person tracks through oil, grease, blood, or other similar materials usually will penetrate or bond to the surface sufficiently to interfere with the lifting process. Recognizing these factors will assist in determining whether an impression can or should be lifted and, if so, the best methods to use. Some of the factors to consider when deciding what methods of lifting or enhancement should be used for two-dimensional impressions include the following: 1. Surface features: porous vs. nonporous, dry, wet, clean, dirty, etc.

2 . Specific surface the impression is on, such as plastic, paper, carpet, fabric, etc. Can

that impression be removed and taken to the laboratory or must it be treated at the scene? 3. Composition of impression: dry residue, wet residue, wet mud, blood, grease, etc. 4. The color of both the surface and the impression and the amount of contrast between the two. 5. The presence of any materials such as dirt, dust, or grease which may obscure the impression or interfere with the lifting process. 6 . High humidity or moisture which may interfere with electrostatic lifting. There is no way to list or prescribe what the best method of lifting might be for every possible situation. As previously mentioned, if the object can be removed safely from the scene, then do so. The choice of whether to later lift or enhance any impressions can then be made in the laboratory. For those impressions on objects which cannot be removed, as a matter of routine procedure and before any lifts are made, always take examination quality photographs first. In those cases where the original impression cannot be retained and a lift must be attempted, crime scene technicians and examiners experienced with the various methods and materials should be able to select the most appropriate lifting method. When original evidence cannot be recovered, careful thought must be given to what lifting technique or other enhancement procedure should be utilized.

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101

Lifting Impressions Electrostatically The Origin of Electrostatic Lifting In May, 1965, Tokyo’s Yomiuri daily newspaper contained an article, the translation of which stated the following.' T he M etropolitan Police D ep artm en t (M PD , Japan) has d eveloped a new m eth od for exact reproduction o f footm arks — often a vital elem en t in crim inal investigations. T he n ew m ethod is the brainchild o f a group o f three M PD identification experts led b y p olice sergeant Sancyasu Toma, ..., w h o used static electricity to produce this sim p le yet highly practical device. T he new m eth od consists o f rubbing the surface o f a black celluloid sheet w ith a piece o f w o o len cloth to generate static electricity. This sheet is then placed on an object bearing a footprint, after w h ich the celluloid sheet is rubbed o n ce again w ith the sam e w oolen cloth. T he static electricity thus generated attack dirt sticking to the surface o f the object, causing th e footm ark to em erge d istinctly on the sheet.

In July, 1970, a 41-year-old police officer named Kato Masao of Shikoku, Japan, realizing that dust had been accumulating around the high-voltage areas of the television set he was working on, concluded that the high-voltage current produced by certain television parts could be used in a similar way to assist in lifting latent footwear impressions. After further research, a static electricity machine that could produce 14,000 volts was combined with an electrode plate and a black vinyl sheet to form the first electrostatic lifting device.^ This initial machine had to be plugged into a main current source in order to operate. It utilized a permanent lifting plate which necessitated that each lifted impres­ sion be photographed or transferred to gelatin or adhesive material before the lifting plate could be used further. In 1981, Young and Morantz created a prototype battery operated electrostatic lifter and in 1983, Brennan et al. produced battery operated electrostatic lifters for use at the Metropolitan Police Forensic Science Laboratory (Davis, 1985 and 1994). Later, Foster and Freeman produced the first commercially available portable high-voltage electrostatic lifting device that operated on rechargeable batteries and utilized separate pieces of lifting film. Today, there are several commercially available high-voltage electrostatic lifting devices, which have proven very effective in the electrostatic lifting of dry residue footwear impres­ sions. These devices are portable and consist of (1) a main unit housing a rechargeable battery-operated, high-voltage source of approximately 10,000 to 15,000 volts, (2) a ground plate and a cable that connects the ground plate to the main unit, (3) a metal hand-held probe, and (4) special lifting film. The parts are housed in a briefcase, making them convenient to transport and use. The Dustmark Electrostatic Lifting Kit, pictured in Figure 4.1, was developed and commercially produced in 1984 by Foster & Freeman Ltd.^ In 1986, another commercial lifter, the Electrostatic Dust Print Lifter, pictured in Figure 4.2, was ’ Personal communication from FBI Legal Attache, Tokyo, December 20, 1965. ^ An electrostatic method for lifting footprints. I n t e r n a t i o n a l C r i m i n a l P o lic e R e v ie w , National Police Agency, 272:287-292, 1973. ^ Foster and Freeman, Evesham, Worcs., England.

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Footwear Impression Evidence, 2nd Edition

F ig u r e 4 .1 T h e D u stm a rk e le c tr o sta tic liftin g k it m ade by Foster 8k Freem an, Ltd.

produced by the Kinderprint Company, Inc/ The Electrostatic Dustprint Lifter, pictured in Figure 4.4B, is produced in Sweden/ A smaller hand-held portable unit, called the Pathfinder ESL Unit, is produced in England^ and measures approximately 4 x 6 in. (Figure 4.4C). The lifting film for these devices can be either a black vinyl or polyester film coated on one side with a conductive metal laminate. Lifting films are available pre-cut in indi­ vidual sheets or in long rolls. Figure 4.3 depicts some of the basic components of the electrostatic lifting apparatus. When the high-voltage source is turned on, this device creates a static charge on the lifting film causing the dust or residue particles composing the footwear impression to transfer to the underside or black layer of the lifting film. Dry dust and residue impressions are Kinderprint Company, Martinez, CA. Kjell Carilson Innovations, Stockholm, Sweden. ^ K9 Scene of Crime Equipment Ltd., Northampton, U.K.

Treatment of Two-Dimensional Footwear Impressions

Figure 4.2

103

T h e ele c tr o sta tic liftin g k it m ad e by th e K inderprint C om p an y.

light in color so they contrast very well on the black lifting film. Since the film is in direct physical contact with the impression, the transferred footwear impression on the film will remain true in size.

Applications of the Electrostatic Lifting Device With electrostatic lifting devices, dry origin footwear impressions can be lifted from vir­ tually any surface, both porous and nonporous. The device works best on dry dust or dry residue footwear impressions that have been tracked across surfaces that are relatively clean. For impressions in that category, the device is excellent at lifting footwear impressions. If the impressions were wet when they were made (wet origin) or if they become wet or damp prior to lifting, a greater bond will occur between the impression and the surface and the electrostatic lifting device will work poorly or not at all. It is important to under­ stand that the electrostatic lifting device is useful for impressious of dry origin, and not

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Footwear Impression Evidence, 2nd Edition

GROUND o r GROUND PLATE

Figure 4.3

S om e of th e b asic parts of th e e le c tr o sta tic liftin g d ev ices.

impressions of wet origin. It is also important to remember that impressions that the electrostatic lifter does not lift are not destroyed. Therefore, in cases where it is not known if an impression is of wet or dry origin, the use of the electrostatic lifting device will not risk the loss of or damage to the impression. Not all dry impressions can be successfully lifted. Attempts to lift residue footwear impressions on a dirty surface that itself contains loose residue will result in both the impression and the background residue being lifted together. The lifting film will be covered with residue and the footwear impression will be lost in it. However, if the shoes of the suspect are damp or sticky and the suspect then walks through a dirty surface, it may be possible to recover negative impressions where the residue on the surface adhered to the shoe and was removed, and the negative image of the shoe outsole remains. It has always been a struggle to successfully photograph, or otherwise recover, certain types of dust and residue footwear impressions, particularly if their contrast with the substrate was poor. In addition, some impressions are totally latent and may go undetected. The electrostatic lifting device permits the location and recovery of footwear impressions of these types that must otherwise be overlooked, ignored, or lost. In fact, it is an excellent crime scene device with which to make a "blind search" of areas where it is likely that the suspect walked. The best way to familiarize oneself with the usage, applications, and limitations of the electrostatic lifting device is to try different lifting procedures on a variety of both dryand wet-origin impressions and on a variety of surfaces. Equipped with this experience, the use of the electrostatic lifting device at crime scenes and in laboratory casework becomes an easy routine.

Procedure for Using Electrostatic Lifting Devices Whenever using an electrostatic lifting device, make sure that it is fully charged. To lift an impression with the electrostatic lifting device, the following procedures should be used:

Treatment of Two-Dimensional Footwear Impressions

105

(A)

Figure 4.4

L ifting an im p ressio n from a p iece of paper w ith an e le c tr o sta tic L ifting d ev ice (A).

Position the grounding device. A good ground is essential when making an electrostatic lift. The metal ground plate most commonly used is a bare metal aluminum plate. A piece of the lifting film placed with the metalized side down, and either placed along side of the impression, as shown in Figure 4.4B^ or beneath the charging unit, also provides an excellent ground. In difficult situations, when these methods do not result in a good ground, a ground lead connected to a radiator, metal pipes, or other grounding location in a house or building, should be considered. The ground wire of the electrostatic lifting device must be attached to whatever ground is being used. The position of the ground also depends on the location of the impression and the surface it is on. This is explained in the following four examples: 1. Whenever possible, position the ground directly beneath the impressioned item. This would be the best choice in the case of impressions on paper, unattached carpeting or scatter rugs, and other movable items. In cases involving small pieces of paper where the lifting film or ground may be larger than the impressioned item, place a piece of clear chart board or similar nonconductive material between the impressioned item and the ground as a separator. This will keep the lifting film separated from and prevent it from touching the ground. If the metalized layer of the lifting film comes into contact with the ground, arcing will occur, and the device may not work or be as effective. The arrangement for this lifting situation is illus­ trated in Figure 4.3 and 4.4A.

Carllson, R., D u s t p h n t L if te r I n s tr u c tio n M a n u a l, Rjell Carllson Innovation, Sundbyberg, Sweden, 1998.

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Footwear Impression Evidence, 2nd Edition

(B )

(C)

Figure 4.4

(con tin u ed ) T h e E lectr o sta tic D u stp rin t Lifter, m ade in S w ed en , u sin g a roll of film to m ak e a lift of a Larger surface area (B). A p ie c e of Lifting film , w ith th e m e ta liz e d sid e facing d ow n , is b ein g used as a ground p late. [N ote: T h e m eta liz ed film sh o u ld be placed on th e gound and sh ou ld n ot be placed on a p iece of board, as it appears here, w h ic h w as d one o n ly to provide co n trast in th is pLiotograph.] A co m p a c t h an d -h eld Lifting d ev ice (C).

Treatment of Two-Dimensional Footwear Impressions

107

UFTING FILM

GROUND PLATE (m etal side face dow n) Figure 4 .5 The ground plate can be placed next to the lifting film in situations where it cannot

be placed beneath the impression.

2. Very often the impression will be on a surface, such as a floor, where the ground cannot be placed beneath the impression. In those instances, position the ground 2 in. away from the impression. This is depicted in Figure 4.5 and also in Figure 4.4B, where a piece of lifting film, with the metallic side facing down, is used as the ground. The ground must make good contact with the surface. On uneven surfaces, use of the lifting film as a ground works particularly well, since the film provides better contact with the surface than a rigid metal plate. 3. If the impression is on a surface such as a door, chair seat, etc., place the ground so it makes maximum contact with the surface of the opposite side of the impression. For example, in the case of a door, the ground can be taped to the other side of the door (Figure 4.6). In the case of the chair, it can be taped beneath the chair seat. To be most effective, the ground should be in maximum contact with the surface. 4. Occasionally, the footwear impression will be on a metal object such as a car hood or other metal surface. In those cases, in lieu of using a metal plate or the metalized side of the lifting film, the ground lead can be attached directly to the car frame or the metal surface. However, for impressions on metal objects, an alternate proce­ dure, described below, must be used for the placement of the lifting film. Prepare and position the lifting film over the impression. Carefully position a piece of lifting film over the impression with the black side facing against the impression. The black side will face down in direct contact with the impression and the metalized side will face up, as shown in Figure 4.4A. The lifting film should be carefully placed so as not to disturb or smear the impression. Never slide the lifting material over the impression. Once the film has been positioned, do not move it. The lifting film should not be touching any part of the ground plate or film. In cases where the impressioned surface is metal, carefully place a piece of clear, thin mylar or polyester film over the impression. Then place a slightly smaller piece of lifting film, black side down, over the acetate. The acetate should be bigger than the lifting film to

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Figure 4 .6

T h e ground plate can be fa sten ed to th e o p p o site sid e of a large object, su ch as a door or desk top.

ensure that no part of the lifting film will come in direct contact with the underlying metal surface. Continue with the lifting procedure as outlined; however, remember that the lifted impression will now be on the clear film. After the impression is electrostatically trans­ ferred, the clear film and the black lifting film can be lifted as one piece. They will naturally stick together. They may be separated later, if necessary. The black film will provide the necessary contrast to permit observation of any lifted impressions. This lifting arrangement is illustrated in Figure 4.7.

of METAL SURFACE Figure 4.7 When lifting an impression from a metal surface, a piece of clear Mylar can be placed over the impression and then covered with a smaller piece of lifting film. The Mylar will provide a separation between the metal surface and the metalized lifting film.

Treatment of Two-Dimensional Footwear Impressions

109

Marking the lifting film to denote its position on the impressioned surface in order to later facilitate the orientation of the lifted impression has been suggested (Hamm, personal communication). It is common to mark lifts of footwear impressions taken from the top of bank counters. Information such as which teller window the lift was taken from, which direction the impression was leading, and which side of the lift was toward the front of the bank are commonly noted on the edge of such items. The need for this step and incorporation of this information in notes, should be considered prior to making any lifts. Place the probe on the lifting film. To lift an impression, the tip of the hand-held probe should be held in contact with the metalized backing of the lifting film. The voltage can now be turned on. It is usually only necessary to turn the voltage on a low setting, although in cases where the current must travel over longer distances or through thicker materials, or when the ground is not as effective, a higher setting will be required. The application of sufficient voltage will cause the lifting film to be drawn down tightly against the impres­ sion. If arcing or sparking occurs, the voltage is too high. There is no need to move the probe around during the charging of the film, but it should remain in contact with the film during the entire procedure. In some instances, air pockets will be trapped beneath the film. These will often disappear in a few seconds after the voltage charge has been applied. If any air pockets remain trapped beneath the film, they may be rolled out with a clean fingerprint roller or brayer while the voltage remains on. This should be done very gently by lightly passing the roller over the film. The weight of the roUer is all the pressure that should be used. If air pockets are not removed, no lifting will occur in those areas. The charge only needs to remain on for 5 to 10 seconds or until all air bubbles have been removed. On occasions, arcing will occur through the film to the ground. This is either because the power is too high or because part of the lifting film is touching or is too close to the ground plate. Turning the power down or moving the ground plate away will remedy this. After the power is turned off, allow the probe to remain in contact with the film for approximately 5 seconds to discharge the film. As the charge dissipates, the film can be seen to relax. Failure to discharge the film with the probe may result in a minor static electricity shock to the person who pulls the film off the impression! Removing the lifting film. The film can now be removed from the impressioned area by carefully peeling it off from one end to the other. Once the film is removed, lay it on a clean flat surface with the black side facing up. It may be placed in a box or folder to properly store it. In a totally dark room, examine the film carefully with a bright oblique light source to see if an impression has been transferred to it. If this is not possible at the crime scene, then all lifts should be saved until they can be examined in total darkness. Film should never be discarded without first carefully examining the film in a darkened room in this manner. Many times, lifting film viewed in normal room lighting and without a strong oblique light source will initially appear to contain no impressions, only to find later that examination of that film in total darkness with a strong oblique light reveals the presence of faint, but valuable impressions. Figures 1.5 and 4.8A and B show both high-contrast photographs of original impres­ sions, prior to lifting, and electrostatic lifts of the same impressions. Figure 4.8C depicts an unusual lift of both a positive and a negative impression made by the same shoe at the same crime scene. Some residue impressions contain heavy deposits of residue or dust. In those cases, the first lifting process may result in a lifted impression with too much residue. A second

no

Footwear Impression Evidence, 2nd Edition

¡A)

(B)

Figure 4 .8 A faint, dry residue impression after high contrast photography (A) and after lifting with the electrostatic lifting device ¡B).

lift of the same impression should be made because it sometimes results in a lifted impres­ sion that is clearer or contains additional detail. Whenever using the electrostatic lifting device, it is possible to receive minor static electric shocks from the lifting film, the ground plate, and the metal probe. These shocks are a minor nuisance similar to those that might be received after walking over a carpeted surface and touching a door knob on a dry day. They can easily be avoided by not touching those parts when the current is on and by allowing the probe to remain on the metalized

Treatment of Two-Dimensional Footwear Impressions

111

'

.-.i; t/4 12% 12% 12% 12 % 12% 13 13 % 13 % 13% 13%

Figure 6.9 (continued) part of that survey, which included 285,977,000 pairs of men’s shoes in 1995. Of those, 113,736,000 were athletic shoes. Figure 6.10 includes the size breakdown for the total number of men's shoes in all categories, as well as the size breakdown for men’s athletic shoes.

Footwear Sizing

191

Based on United States sales figures through April, 1998, o f 316,215,000 pairs o f men’s shoes, the following gives a breakdown o f the numbers sold and percentage sold, for each half size in U.S. men’s sizes. 6

4,324,000/ 1.4%

11

6Vi

2,646,000 / .8%

11 ‘/2

1

6,766,000 / 2.1%

12

IVi

6,704,000 / 2.1%

12^2

39,147,000/ 12.4% 9,504,000 / 3% 33,030,000 / 10.4% 1,603,000 7.5%

8

17,969,000 / 5.7%

13

%V2

20,371,000/6.4%

13 ^2

9

33,231,000/ 10.5%

14

3,492,000/1.1%

9 * /2

33,601,000/ 10.6%

15

1,657,000 / .5%

10

43,332,000/ 13.7%

16

363,000/.!%

10 ^2

38,205,000/ 12.1%

17 +

115,000/^ R2(1-10) L3(1 1 0 ) « ^ R3(1-10) L4(1-10) R4(1-10)

_ 1/1600 X

^,.......J,|)),,,)||||||||iiiiiiiiiiiiiiiiiiiiiiii»

Figure

1 0 .3 A sim p lifie d ex a m p le of h o w c o m b in ed cla ss ch a ra cteristics can reduce th e p o ssib le num ber of sh o es th a t co u ld h ave m ade an im p ressio n .

each shoe in 10 different distinguishable positions and which would be reflected in the impression, could further reduce the number of single shoes sharing this characteristic from 2,500 (out of 10,000) to 250 (out of 10,000). The combined occurrence of left and right shoes from the same respective left and right molds and having the toe bumper guard positions in the same respective positions on each of the respective left and right shoes would be approximately 6 pairs of shoes out of 10,000. This may sound like an extreme example; however, in certain factories, depending on the method of manufacture and the number of potential independent class characteristics, this manufacturing scenario does occur. It is noted that with shoes made from molds made with CAD-CAM or EDM technology, the class characteristics of all of the 10,000 shoes might be indistinguishable.

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On the other hand, soles made with expanded materials or cutting processes could result in more significant combined class characteristics. The numbers used in the above example are approximate of most shoes of average popularity or of off-brand shoes. On the other hand, a few of the largest footwear manu­ facturers may produce as many as 500,000 pairs of shoes in one year for a few of the very popular designs. With 500,000 shoes, the most common sizes would require approximately 10% or 50,000 pairs of shoes to be made. To meet this demand, the manufacturer might require 8 to 12 molds to be made to produce that size. For many reasons, the mold may have distinguishable features. Further, production of this quantity of shoes often involves the need to use more than one factory, which means the use of even a greater number of molds. The random matching of shoes from different left and right mold cavities and other variables from factory to factory and mold to mold could potentially reduce to a lower number the total number of pairs of shoes that were identical in all combined class characteristics. An actual case example, where a manufacturer was contacted to determine the number of Nike Air Dynamic Flight shoes of a particular size and design and sold in a particular state, is furnished below (Whitlock, 1994). Production Totals: USA total all sizes: 227,544 Size 13:Black - 8136 pairs White - 7032 pairs Total - 15,168 pairs Distribution for the State of Georgia (U.S.) All sizes: 6570 pairs Size 13: 433 pairs (approximate) The above examples and discussion are not in any way to suggest that statistics or distribution numbers can or should be used to forecast the number of possible shoes sharing certain class characteristics. Nor is it to suggest that shoes or pairs of shoes can be presumed to be so unique in their combined class characteristics as to allow for the positive identification of footwear impressions based on those characteristics alone. Although, there are some extreme cases where the manufacturing process normally involves several inde­ pendent components or processes which results in several independent class characteristics, the shoes or pairs of shoes could theoretically be unique. There is no way to absolutely know this short of the impossible task of examining every shoe of that design that has ever been made. It must be understood that each of those independent class characteristics can, and do, occur repetitively, and can therefore potentially re-occur in combination with the other class characteristics. The presence of several independent combined class character­ istics does noty by itselfy evidence uniqueness. The understanding and recognition of the potential for the presence of combined class characteristics and their resulting value can, however, in some cases contribute significantly to the overall examination results. Another point, previously discussed with regard to the footwear database in Chapter 8, should be reiterated here. That point is the innumerable thousands of designs of footwear worn by the population and the many different and distinguishable sizes that each is sold in. Each of those shoe designs are distinguishable because of their class characteristics of size and design. A shoe in a particular size and design is not rare in the sense that it is

Class and Identifying Characteristics

335

mass produced. However, when that shoe is sold and worn by one individual against the tens of thousands of shoes in other design and size combinations, the link between a shoe impression at the crime scene with the specific class characteristics of a shoe of a suspect is highly significant.

Identifying Characteristics Individual Identifying Characteristics The scientific principles gu id in g an exam in ation o f footw ear incJude the laws governing the fact that things in nature occur random ly and thus differ ... that those random occu r­ rences yield uniqueness and that q u estioned im pressions acquire or receive these unique features through the physics o f (physical) contact o f objects (Paulisick, 1994).

Tuthill states “Individual characteristics ... can be defined as characteristics that are unique .... They are basically attributed to natural deviation and to damage (wear and tear).” ' In the examination of footwear impression evidence, individual identifying character­ istics are characteristics that result when something is randomly added to or taken away from a shoe outsole that either causes or contributes to making that shoe outsole unique. Cuts, scratches, tears, rocks wedged in the outsole, gum, shoe-patching material, holes, and air bubbles are all examples of identifying characteristics because they all occurred with some degree of randomness. The term random infers that the size, shape, orientation, andlor position of the characteristic depends, to some degree, on chance. The size of the characteristic is relevant because it is random and can potentially occur in any size. Size may include the width or length of a scratch, or the diameter or depth of a hole. Shape is relevant because it is random and can occur in an infinite number of ways. Shape is highly significant if the shape of the characteristic increases in its complexity. A characteristic having more features, as opposed to a small round cut is more unique. Orientation refers to the way in which the characteristic is arranged or positioned on the sole. For instance, the way in which a scratch is oriented or aligned can be in many directions. Position refers to the part of the sole at which the characteristic has occurred, i.e., the toe, ball, arch, heel, etc. It is important to note that all of these attributes occur independently of one another, a fact which further contributes to the overall uniqueness of the occurrence of each, and particularly when two or more separate characteristics are on the shoe. Figure 10.4 illustrates several examples of individual identifying characteristics result­ ing from ( 1) items being added to the outsole, such as hardened tar or gum on the outsole and rocks wedged in the sole design or (2) portions of the outsole being lost through cuts, gouges, scratches, or areas of the design being randomly torn away. Although unique identifying characteristics usually occur through the use of the shoe after the shoe is purchased and worn, some, including random air bubbles, and others occurring in soles during the manufacturing process, either contribute to, or result in, a shoe's individuality before it is ever worn. These were discussed in Chapter 7. Some unique identifying characteristics are also caused by wear. Those characteristics include the Schallamach abrasions and ragged edges of holes, and were discussed in ' Tuthill, H., Individualization: Principle and Procedures in Criminalistics, Lightning Powder Company, Inc., Salem, OR.

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Figure 10.4

E xam ples of d ifferen t in d ivid u al id e n tify in g ch a ra cteristics in clu d e th o se charac­ teristics th at have been ran d om ly added to th e sh o e o u tso le , such as gu m or tar (A) or rocks w edged in th e o u tso le (B) and th o se th a t h a v e resu lted w h en so m e th in g has been ran d om ly rem oved from th e o u ts o le su ch as in th e ca se o f cu ts, scra tch es, ch u n k s, or tears (C) or w h en v oid areas of th e o u ts o le ran d om ly resu lted during th e m a n u fa ctu rin g p rocess, as in th e case of air bubbles (D).

Chapter 9. Other features related to changes which occur to certain components of the shoe as it ages may also result in random identifying characteristics. For instance, one case reported impressions of the size of the sole which recorded on a victim s T-shirt and which reflected cracks that were present on the side of the rubber sole. Contact with the manu­ facturer confirmed that those cracks were acquired features that occurred after they were manufactured and that varied from shoe to shoe (Whitlock, 1994).

class and Identifying Characteristics

Figure 10.4

337

(continued)

There also have been instances when a shoe sole was manufactured with recycled materials from old worn tire treads. These soles are unique due to the rarity of their pattern as found in footwear, their particular condition, and most importantly their specific cut; that is, the orientation and features of the tread and cordage of the tire fragment are different on each sole that is made.^ 2 McAllister, R., U.S. roads turn tires into soles, Footwear News, August 1992, p. 46.

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Footwear Impression Evidence, 2nd Edition

(A)

(B )

Figure 10.5

R everse photograph of an enlarged area of a p ortion of a sh o e (A) c o n ta in in g a variety of sh ap es and s iz e s o f random in d iv id u a l id e n tify in g ch a ra cteristics and an im p ressio n (B) of th at area of th e sh o e. N o tic e th e im m e n s e va riety of sh a p es and siz e s of th e random characteristics.

Identifying characteristics, because of their independent and countless possible origins, can range from the tiniest, almost obscure pinpoint-sized characteristic to one having tremendous distinctness and uniqueness. Figure 10.5 depicts a small sampling of the countless variety of random cuts on a small area of a shoe. Some of those are very small and almost without shape, while others are larger and contain both shape and direction. Wlien unique identifying characteristics of sufficient value and/or number are present in the impression and correspond with those in the shoe outsole, that outsole can be positively identified as having made that impression. Several things must first be considered by the examiner in order to assess the value that each identifying characteristic contributes toward identification. Those considerations include ( 1) the clarity of the characteristic, (2) its reproducibility and repeatability in test impressions of the known shoe, (3) its confir­ mation as a random occurrence in the shoe, and (4) its degree of uniqueness by its combined size, shape, position, and orientation. Clarity of the Characteristic in the Q uestioned Im pression The characteristics must be sufficiently clear in the questioned impression to correlate with the corresponding characteristics in the shoe outsole. The term sufficiently clear does not necessarily denote the crispest and sharpest detail possible, but rather a reasonable amount of clarity to adequately correlate the size, shape, or some detail of the characteristic in the questioned impression with the known shoe. A characteristic that is clear and correlates well with the known shoe will carry far more value in the examination than one that is not as clear or which can hardly be distinguished. This is because it can be more closely

class and Identifying Characteristics

339

associated with the respective feature on the shoe and because its individual features can be more closely examined. In some instances, characteristics are not sufficiently clear to correlate well with those in a known standard. Some clarity problems occur due to the varied or limited reproduc­ ibility on some substrates and can be recognized as such. For instance, impressions in certain substrates, such as hard soil or dry sand, usually do not enable good reproduction and retention of fine detail. Impressions made in wet materials, such as blood or mud, may result in the squeezing of excess materials into the characteristics, either filling in or masking portions of the features of those characteristics. In addition, some characteristics that have been reproduced well in the impression may lose detail, may be partially obscured, or may be totally lost in the process of recovering that evidence. The limited clarity may prevent or restrict the use of a random characteristic. If the presence and position of a characteristic, both on the outsole and in a questioned impression are the same, but the detail is of limited clarity, the characteristic may still be of some value regarding some of its features such as size and position. Characteristics that are of such limited clarity that they only appear as a possible disturbance in the questioned impression, even if they are in the same precise spot, are of less or possibly no value in the examination. The examiner must be as objective as possible in associating identifying characteristics on a shoe with characteristics in the questioned impression. There must be some degree of association between the random characteristics on the shoe and the character­ istics in the questioned impression before that characteristic can be used in the comparison. That degree of association, however slight it may be, must still be clear enough to be demonstrable to the layman. Figure 10.6 depicts four impressions of a small area of the same shoe. Three charac­ teristics (arrows) are visible in three of the four impressions, but with different degrees of clarity. In the fourth impression, the characteristics appear either very minimally or do not appear at all. Three inked impressions of the same area of the shoe are shown in Figure 10.7. The slight difference in the amount of ink and/or pressure causes these variations. A reverse photograph of the portion of the shoe used to make these impressions is featured in Figure 10.8. Reproducibility and Repeatability The reproducibility and repeatability of a characteristic in both questioned impressions and known impressions also enter into the assessment of detail in a characteristic. Any characteristic will always vary slightly in its reproduction from impression to impression, even under very similar circumstances. Although the exact conditions and materials that existed in the questioned impressions can never be precisely duplicated, the reproducibility can be assessed by making several test impressions of the known shoes. Figure 10.7 depicts three successive inked impressions of the same small area of the same shoe that was used to prepare the impressions in Figure 10.6. Even under extremely similar circumstances, i.e., the same person making the impression, the same surface, the same ink pad, etc., there is still some slight variation in the precise manner in which the characteristics reproduce. Regardless of these slight and normal variations, the basic features will reproduce and repeat in most, if not all, of the impressions. The precise quality of the reproduction of characteristics will vary in questioned impressions as well, depending on the conditions involved.

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340

(B)

(C)

(D)

F ig u r e 1 0 .6 C h a ra cteristics from th e sa m e area of th e sh o e in Figure 10.8, w h ich also m ade th e im p ressio n s in Figure 10.7. T h e se ch a ra cteristics w ill reproduce w ith a variety of clarity d epending on th e m aterials in w h ich th e y are m ade. S o m e im p ressio n s w ill co n ta in a clearer reproduction of th o se ch a ra cteristics, as d ep icted in (A) and a lso in Figure 10.7; so m e m ay co n ta in less clarity due to factors su ch as an ab sorb en t su b stra te and th e sq u eeg ee effect in a blood im p ression (B) or th e fragile nature of so m e d u st im p r e ssio n s (C). T h e im p ressio n in loose sand (D) failed to reproduce th e sa m e th ree ch ara cteristics w ith su ffic ie n t clarity to be reliably evalu ated or of any valu e.

In most instances, identifying characteristics will reproduce in a similar and consistent manner. In those cases, it is relatively easy to examine and assess the corresponding characteristics in the questioned impression. However, there are characteristics of the type which do not always reproduce. An example would be a very shallow abrasion or remnant of a cut, which is extremely sensitive to the substrate and pressure. It may only reproduce occasionally due to its nature. The fact that it may only repeat occasionally does not diminish its value. Characteristics acquired in footwear are not only diverse in their random features, but because of the normal variables of a dynamic footwear impression, some may print clear one time, less clear a second time or not at all. This is normal. There are other reasons why a characteristic may not appear in an impression. A small cut or scratch might be filled with mud or blood, which would obscure its presence. Or contaminants or other problems on the receiving substrate could prevent the recording of these features.

class and Identifying Characteristics

341

Figure 10.7

R ep rod u cab ility of ch a ra cteris­ tic s. C h a ra cteristics, su ch as th o s e m arked, vary in th e p recise w ay th ey reproduce. In th is ex a m p le o f th ree seq u e n tia l in k ed im p ressio n s from th e sa m e sh o e, th e a m o u n t of in k and pressure as w ell as o th er su b tle variables c o n ­ trib u te to v a riation s of th o se ch a ra cteristics.

Confirmation of the Characteristic as Random Each identifying characteristic being considered in the examination must be confirmed as random. Random characteristics which have been added to the outsole will be composed of foreign matter such as rocks, gum, nails, tacks, etc. and can be recognized and verified as such. They obviously were not manufactured with the shoe and therefore are unique to that shoe only. Random characteristics that are a result of the loss of part of the outsole (cuts, scratches, gouges, etc.) will be recognizable under magnification as part of the sole that has been removed. Figure 10.8 depicts an enlarged and reversed photograph of the same small area of the shoe used to make the impression in Figures 10.6 and 10.7. The two glossy holes (A) are air bubbles, while the torn area (B) represents random damage to the shoe. Areas representing coded manufacturer's marks (Figure 10.9A) or damage to a mold, as discussed in Chapter 7, will appear as raised areas of the shoe outsole and not like cuts or scratches, which are areas that have been randomly removed. If a piece of debris or rubber should fall into and temporarily stick in a mold, a depression or disturbance in the outsole would result, as pictured in Figure 10.9B. This feature, although it would look like a portion of the sole was removed, would have smooth features unlike an area torn from the sole. Examiners should be familiar with recognizing these different characteristics and how they are caused.

Footwear Impression Evidence, 2nd Edition

342

Figure 1 0 .8 T h e ty p ica l sm o o th and g lo ssy features of th e air b u b b les (A) is ea sily d is tin ­ gu ish ed from th e rough and torn featu res of th e random cu t (B). T h is p ortion of th e sh o e w a s u s e d to p r e p a r e th e im p r e s s io n in Figure 10.6 and Figure 10.7.

The Value of One Confirmable Random Characteristic In considering whether another characteristic of an identical size, shape, and position on one shoe could occur on a second shoe, a general understanding and appreciation of the probability of that exact characteristic being duplicated in another shoe needs to be addressed. The probability example provided here is only for discussion purposes and is not meant to imply that the data needed to apply precise mathematical probabilities could be obtained and used to value random characteristics in actual case examples. Probability can be defined as the number of ways something can occur divided by the sum of both the number of ways it cannot occur plus the ways it can occur. Thus, if the numbers 1 through 10 are placed in a hat, the chances of drawing the number 5 would be one in ten and could be expressed as: 1 (ih e n u m b er o f ways o f selectin g 5) Probabiliry o f draw ing 5 9 (n u m b er o f ways o f n ol selectin g 5) + 1(th e n u m b er o f w ays o f selectin g 5) w hich equals 1/10, or o n e out o f ten ch ances.

In the above example, it is easy to define the number of possibilities of the occurrence of each number and then the probability of each number being drawn. With regard to random characteristics that occur on shoe outsoles, the problematic assessment is far more complicated. In fact, in reality, there is an unlimited number of different unique random characteristics that could occur on a shoe, any of which could be on any part of the outsole. The importance of just one very small confirmed charac­ teristic on a particular part of a shoe outsole is discussed below. To illustrate the value of a single random characteristic, one examiner (Stone, 1984) offered the following example. To demonstrate the signficance of a random characteristic, he created an example using a simple pinpoint-like cut that could be contained in the space of one square millimeter. For discussion purposes, this cut was treated as having no other descriptive features such as shape or orientation on the outsole. Placing a metric grid over the shoe in this example, he revealed that it contained approximately 16,000 square millimeters of surface area on its outsole. Thus, with over 16,000 different possible places that small random pinpoint-sized characteristic could occupy, the chances of it appearing on any particular point in the outsole can be calculated to be 1 out of 16,000. Probability =

15,999+1

16,000

Class and Identifying Characteristics

343

(A)

■ ¡■ ¡■ ■ ¡■ ■ I

% ^ 3 :% „ •,J%''..%^% -% ■% -% ;'.% ?% ■■•'%---n ■;

% m vH^4H '^^ii^iii^li-%-%Ti-

**^ik •% ■%

:

.

•-Ifc ■■'% •••% -p-r

%

(B) if.i

■ ^ % :'

■'

Figure 1 0 .9 In ten tio n a l m arks placed in th e m o ld by th e m an ufacturer or d am age to th e m o ld itself w ill be in th e form of a d ep ression on th e m old surface and th erefore a raised area on th e sh o e o u ts o le (A). W hen a foreign ob ject su ch as a p ie c e of rubber, flash in g, or debris falls in to a m o ld and a sh o e is m old ed over it, a d ep ression in th e surface of th e o u ts o le w ill resu lt (B).

A cut of this type and the space it occupies compared to the number of possible positions on the outsole is illustrated in Figure 10.10. If more than one random characteristic is present on the bottom of the shoe, then the chances of another shoe having those combined characteristics in the same positions can be expressed as follows: C

N! (N-R)!R!

344

Footwear Impression Evidence, 2nd Edition

where C is the chance of the combined occurrence, N is the number of available spaces, and R is the number of random characteristics. (The mathematical expression “!” means that number is multiplied by itself minus 1, multiplied by itself minus 2, multiplied by itself minus 3, and so forth. So “5!” would be expressed a s 5 x 4 x 3 x 2 x l = 120.) With a shoe bottom having a possibility of 16,000 positions (N = 16,000) for a small pin-point characteristic, the combined occurrence formula above yields the following probabilities: C h an ce o f co m b in ed N u m b er o f characteristics

occu rren ce

2

1 out o f 127,992,000

3

1 ou t o f 683 b illion

4

1 ou t o f 2.7 q u ad rillion

5

1 ou t o f 8.7 q u in tillio n

6

1 out o f 23 sextillion

7

1 o u t o f 53 sep tillion

8

1 ou t o f 106 o ctillio n

9

1 ou t o f 189 n on tillion

10

1 out o f 300 d ecillion

Thus, the chances of another shoe containing the same two pinpoint characteristics in the same two positions on another shoe is 1 in 127,992,000; for three characteristics, the chances are 1 in 683 billion, and so forth. Remember that these simplified statistics are for confirmed simple and small nonde­ script random pinpoint cuts of independent origin. They do not take into account the many different shoe designs, shoe sizes, wear characteristics, or manufacturing variables which have already reduced the population of shoes that possibly made the impression. More importantly, they do not account for the particular descriptive features of shape and orientation, that may be associated with each random characteristic and which, together, fully constitute the uniqueness of the characteristic itself. Statistics are used here only to generate an appreciation of the importance and signif­ icance of random characteristics and are not intended to represent actual statistics or circumstances that might surround a specific case. Nevertheless, the tremendous signifi­ cance of confirmed unique random characteristics on the outsole of a shoe is clearly demonstrated by this example. U niqueness of the Characteristic The uniqueness or unusualness of the characteristic must also be considered. Some char­ acteristics are extremely unusual in their shape, size, and orientation, while others, like the pinpoint characteristic used in the prior example, are a minimal representation of a random characteristic. Figure 10.5 depicts a shoe outsole that contains various examples of random identifying characteristics. The minimal characteristic, perhaps best described as a pinpoint characteristic, is valued more for its position and size in the outsole then it is for any shape or orientation features. On the shoe outsole there are many ways a pinpoint characteristic could have occurred, although it would still be extremely rare, if at all possible, to find it in the identical position on another shoe of the same size and design. The weakness of a limited characteristic of this type lies in the difficulty in specifically associating it with the corresponding characteristic in the impression. In some cases, it may be difficult to deny

Class and Identifying Characteristics

345

lBo

uc lio LVo 130 iio-

2.00

lio 18o

Îto ,f,j ' ISù' (A)

I

no'> no too 9o 80

70

So Sc

tki %o io V

¿V?

/o

Clio" S o

^

ic

¡LO

/O

Figure 10.10

A m etric grid placed over th is o u ts o le (A) d iv id es it in to a p p roxim ately 16,000 mm^, each of w h ich can h o ld a p in p o in t ch a ra cteristic, su ch as th e o n e sh o w n w ith th e arrow. T h e enlarged area d ep icts th at ch a ra cteristic (B).

the possibility that what appears as a single pinpoint characteristic in a questioned impres­ sion could have occurred for other reasons or be attributable to contamination or coinci­ dence. In Figure 10.7 the three impressions were made by the same shoe. Yet there are numerous pinpoint-sized characteristics that appear in one of those impressions, but not in the other two, and which are attributed to the contamination of the outsole. Some of those characteristics were due to particles of grit that had temporarily adhered to the outsole. The grit had prevented contact of the outsole with the surface in that area, therefore preventing a recording of the outsole at that point. In the instance of a single pinpoint­ like characteristic, it might not be possible to determine whether the resulting void area in the impression was attributable to contamination or damage to the shoe. Any one of those void areas could coincidently be at the location of a single pinpoint cut in a suspect's shoe. Of course, if two or more of these characteristics were present in the precise positions

346

Footwear Impression Evidence, 2nd Edition

(B)

Figure 10.10 (continued) in both the impression and the shoe, then they collectively would become more valuable. This is because their occurrence in the same multiple points due to coincidence is unlikely and quickly becomes impossible as the number of points increases. When assessing the value of these characteristics during an examination, the likelihood of the random characteristic of a particular size, shape, and orientation occurring in the same exact position on another shoe of that size and design is considered. As a single characteristic begins to take on more size, shape, and orientation qualities, as do many of those features in Figure 10.5, it rapidly becomes less likely that another characteristic of the same size and shape would ever be found in the same precise position and orientation in another shoe outsole of the same size and design. Thus, if such a characteristic is found in both a shoe and impression, it also becomes increasingly unlikely and very quickly impossible, particularly as the complexity of the characteristics increases, that this event could be either coincidental or due to contamination.

class and Identifying Characteristics

347

Characteristics Required for a Positive Identification D efinition of an Identification An identification, sometimes referred to as a positive identification, is made when the questioned impression and the known shoe share one or more confirmed random characteristic(s) that, by virtue of their features and placement on the shoe outsole, in the opinion of a qualified footwear impression expert, could not be repeated on another outsole sharing the same class characteristic(s). An identification means the shoe positively made the questioned impression and no other shoe in the world could have made that particular impression. Number of Characteristics Required for Identification The question has often been asked, "How many points of identification do you need in a footwear impression to make an identification?" Obviously this question has arisen from the public's familiarity with counting "points" of identification in fingerprint examinations. In a fingerprint, there are three general features: (1) the bifurcation, (2) the ending ridge, and (3) the island. These three characteristics occur repeatedly on the fingers of all persons and appear in patterns such as arches, loops, and whorls. When one of these features appears in both the questioned and known print, it is referred to as a point of identification. In contrast, the general features of all footwear are not alike. There are literally thousands of designs of shoes, each coming in a large variety of sizes, any of which could be distinguished from one another. And even within one specific make, design, and size, there can be distinguishable manufacturing variables that will further decrease the total number of possible shoes of a particular size and design that could have made the impression. Additionally, its condition, whether new or worn, will further reduce the remaining shoes of a particular criteria. The addition of a clear, confirmable, and multiple featured random characteristic(s) can quickly make this shoe unique. As summarized in Figure 10.11 A, the features used to "identify" a fingerprint and all of the features used to identify a footwear impression are not exactly the same, although both are based on the randomness of the occurrence of certain characteristics and the positioning of those characteristics. With regard to random identifying characteristics in footwear, there is no way to ever determine the statistical probability of any single identifying characteristic's occurrence. However, innumerable possibilities of accidental cuts, gouges, tears, or other identifying random features of varied size and shape is so staggering that the presence of those characteristics, by virtue of their features alone make a shoe sole unique. One single characteristic may have multiple points or features about it. Taking into account both the random placement on a particular outsole's surface and a characteristic's points or features, the chance of recurrence of that characteristic on another shoe, in many cases, is simply not conceivable or possible. Positive identifications may be made with as few as one random identifying charac­ teristic, but only if that characteristic is confirmable; has sufficient definition, clarity, and features; is in the same location and orientation on the shoe outsole; and in the opinion of an experienced examiner, would not occur again on another shoe. The result in any comparison that concludes that a shoe positively made an impression must always take all of the features and areas of comparison into consideration.

Footwear Impression Evidence, 2nd Edition

348

FIN G E R PR IN T S

-Contain 3 types of characteristicsbifurcation, ending ridge and dot, which occur over and over again on the fingers of ail persons, from the embryo stage until decompostition after death -W hereas these characteristics occur repeatedly on the fingers of ail persons, they appear in patterns, namely arches, loops and whorls, but in different frequency and relative position to one another -T h e frequency and unit relationship of these characteristics combine to form a fingerprint that is truly unique

FOOTW EAR IM PRESSIO IV S

(A)

“ Represent only one of many thousands of possible designs, each of which is available in a wide variety of possible sizes

— Can have manufacturing variables and characteristics within that size and design

— Can have wear characteristics, which relate to both the degree of wear and the position of wear, and which are changing throughout the life of the shoe — Can have randomly acquired characteristics which, based on the presence, location, shape, and size, can make that shoe outsole unique.

Figure 10.11

C om p arison of fingerprints and fo o tw ea r im p ressio n s are often m ade (A). Both rely on th e ran d om n ess of th e o ccu rren ce of certain ch a ra cteristics and th e r e la tiv ep o sitio n of th o se ch aracteristics. F ootw ear im p r e ssio n s can also be u n iq u e, but th e u n iq u e n e ss is th e resu lt of slig h tly different criteria.

Parts A and B of Figure 10.12 depict the heel of a shoe and its impression, which reflect one characteristic in common. The characteristic, marked 1, is not in itself sufficient to establish a positive identification due to its limited size and shape features. Notice in the impression there are other characteristics which are not represented in the shoe. These are due to contamination. They were caused by pieces of grit on the shoe or surface that interfered with the impression process, leaving a void area. It is common to observe features that are representative in either the shoe or the impression, but not in both. This can occur due to many reasons, including variations in the substrate, variables in the impression making process, contaminates on the shoe outsole or substrate, and the evolution of old and new characteristics on the shoe sole. The presence of sufficient identifying character-

Class and Identifying Characteristics

349

(B)

SliK)es in the U.S.

Shoes of one design in the U,S. Shoes o f one design and size in the U.S. Shoe o f one design, size, wear 0 and random features

- ^ Shoes of one design, size and wear in the U.S,

F ig u r e 1 0 .1 1 (continued) (B) T h e w orld p o p u la tio n of fo o tw ea r can be rapidly reduced to a sin g le sh o e through th e a g reem en t of c la ss and random in d ivid u al ch a ra cteristics.

istics, particularly if one or more are unique features, can provide overwhelming evidence that the shoe made the impression. In Figure 10.12C and D the shoe conh ins a random characteristic that has multiple features. It contains sufficient size, shape, and orientation characteristics to conclude that it could not be mistakenly due to coincidence or contamination and could have only originated from that shoe. Identifications with just one characteristic are not common and should only be made when the characteristic in the questioned impression is a unique feature and is convincingly the result of the corresponding random characteristic on the shoe. Each case must rest on its own merit. According to Zmuda and Brodie (undated). The question c o m m o n ly asked by the neophyte is specifically w hat num ber o f character­ istics is necessary for an identification and w hat quality m ust these characteristics have? The answer depends upon the u niqueness and individuality o f the characteristics th em ­ selves and the num ber felt necessary in the exam iners ju d gem en t.

In a presentation on footwear evidence, one examiner (Davis, 1985) discussed the importance of size and number of outsole features: Random characteristics ... T hese are the b lem ishes that the w orking surface o f a shoe acquires constantly w hile being worn: cuts, nicks, gouges, scratches, dents, burns, holes, and so on. M ost random wear marks are acquired purely by chance and it is the co m b i­ nation o f these and other things (like general wear) that give a sh oe its unique character.

350

Footwear Impression Evidence, 2nd Edition

(A)

IB)

Figure 10.12 An

im p ressio n (A) and sh o e (B) sharing o n ly o n e sm a ll and fairly sim p le in d ivid u al ch aracteristic (arrow) w o u ld fall sh o rt of u n iq u e n e ss, due to th e lim ite d v a lu e of th a t charac­ teristic alon e. M ore than o n e ch a ra cteristic of th is size, shape, and q u a lity w o u ld be n eed ed for id en tifica tio n . H ow ever, if th a t o n e in d ivid u al ch a ra cteristic w ere m ore c o m p lex and co n ta in ed several d istin c t features, th e im p ressio n (C) co u ld be p o sitiv e ly a sso cia ted w ith th e sh o e (D). Random wear characteristics can be very large or m inutely sm all. A scientist w ould attach m uch greater significance to a large characteristic than to a sm all on e, so the difference betw een footw ear and fingerprint identification should be ob viou s. O n e good 'ch aracteristic, taken w ith other factors like pattern, etc. can be sufficient to identify a sh oe conclusively.

class and Identifying Characteristics

351

(C)

.^



1

^

4:W

ID )

F ig u r e 1 0 .1 2 (continued)

Regarding factors affecting the number of random characteristics needed, it has been stated (Cassidy, 1980) that “a number of factors enter in the number of accidental char­ acteristics required before a positive identification can be established, the most important of which are the examiner’s experience, the impression’s clarity and the uniqueness or significance of the characteristic.” It should be emphasized that a full recording of the footwear is not necessary in a questioned impression in order to make a positive identification. In fact, it is not unusual to make positive identifications of partial footwear impressions that represent only a small fraction of the outsole surface. The identification is not based on the size or completeness

352

Footwear Impression Evidence, 2nd Edition

of the impression, but in the quantity and quality of random individual features in the questioned impression that correspond with the respective portions of the known shoe. Courts have upheld forensic footwear impression examinations as far back as court records are kept. In one ruling, an appellate court^ commented specifically on shoe print identification. That case involved a shoe print on an envelope that shared class character­ istics and six random individual characteristics in common with the suspect s shoe. The court stated “where there are significant general and individual characteristics, such as would provide a basis for a positive identification, shoe print evidence may be as reliable and as trustworthy as any other evidence.” The court further stated “we believe that even one individual characteristic, depending on the nature and uniqueness, could be enough for a valued comparison.” Figure 10.1 IB represents how the combination of class and individual characteristics serves to narrow down the world shoe population to a minute fraction of that population. The agreement of the class characteristics of specific design and size alone reduces other possible shoes to a small fraction of 1%. By considering the wear pattern or general condition of the shoe as well as random individual characteristics, the number of shoes that could have made an impression can eventually be reduced to one. Case Identifications Figure 10.13A illustrates a residue footwear impression that has been enhanced with highcontrast photography. Figure 10.13B is a test impression of the same area of the known shoe. There are many random accidental characteristics on the shoe that are reflected in the known impression. Several of those characteristics also reproduced well in the ques­ tioned impression; others are reproduced with less detail or not at all. This is to be expected because of the various types and conditions of substrates and because of the variation in the way the shoe makes contact with the substrate. In addition, some of the characteristics may have been worn from the shoe with additional wear, prior to seizure of the shoes. Of the various characteristics in Figures 10.13A and 10.13B, some might be sufficient for a positive identification alone, while others would only contribute to an identification. Figure 10.14 depicts a partial impression in blood as well as a test impression of the known shoe. The arrows point to a number of random characteristics. The unevenness of the blood in Figure 10.14A is evident and resulted in some areas of the impression recording less accurately than others. In some areas, excess blood was squeezed or flowed into adjacent areas, obliterating some details. In other areas, there was a better transfer of detail and identifying characteristics that enabled positive identification of the known shoe as having made this impression. The presence of a cut, scratch, or other acquired characteristic that does not appear in a questioned impression does not constitute a basis for non-identification. Rather, this is a very common and expected occurrence. This is because all characteristics do not reproduce in all impressions, due to the varied conditions in the impression making process. Factors like the presence of mud or blood on the sole or the presence of other materials which might fill-in and obscure the characteristic could prevent a recording of that characteristic. The acquisition of new characteristics, before the shoe is seized, could also account for this discrepancy.

State of [llinois v. CharJes A. Campbell, docket No. 71335, agenda 11, Sept. 1991, Supreme Court of Illinois.

class and Identifying Characteristics

353

[A)

IBl

Figure 10.13

A p o sitiv e id e n tific a tio n based on n u m ero u s random in d ivid u al ch a ra cteristics. A lth ou gh n ot all of th e in d ivid u al ch a ra cteristics th a t appear in th e k n o w n im p ressio n (B) also appear in th e q u estio n ed im p ressio n (A), su ffic ie n t ch a ra cteristics in c o m m o n p erm it p o sitiv e id en tifica tio n . T h e ch a ra cteristics p resen t in th e k n ow n im p ressio n and n o t in th e q u estio n e d im p ressio n eith er occurred after th e q u e stio n e d im p ressio n w as m ade or did n ot reproduce in th e q u estio n ed im p ressio n . T h is is n orm al. T h e arrow s p o in t to just a few of th e id e n tify in g characteristics. M any o th ers can be found.

changes in Identifying Characteristics as Shoe Wear Continues After a random identifying characteristic occurs on a shoe outsole, it usually changes as the shoe receives additional wear. How much it changes and how long that characteristic

354

Footwear Impression Evidence, 2nd Edition

(A)

(B)

F ig u r e 1 0 .1 4 A q u estio n ed im p ressio n in b lood (A) and a k n o w n im p ressio n (B) reflect several random individu al id e n tify in g ch a ra cteristics in c o m m o n . O ther ch a ra cteristics h ave been obliterated by ex c e ss blood.

or a portion of it remains on the shoe outsole depends on a number of factors, including the depth and shape of the characteristic itself, the position that it occupies on the shoe (heel, arch area, toe, etc.), and the amount of additional wear the shoe receives. Conse­ quently, some features will change considerably in their appearance as the shoe is worn down while, in the same time frame, others will stay similar in appearance.

class and Identifying Characteristics

355

Research involving 12 pairs of shoes over a period of 50 days concluded that (1) both the disappearance and appearance of random characteristics occurs gradually over time, (2) smaller random characteristics disappear more frequently and faster than larger ran­ dom characteristics, (3) the majority (83.5%) of random characteristics were still present after 50 days, and (4) random characteristics both appear and disappear more frequently in the heel areas and beneath the metatarsal area of the feet."^ Figure 10.15 depicts impressions of a small area of the center of a heel that were taken in March, May, and September of a single year. The shoes were worn for several days each week during the entire time period. Some random characteristics present in the March impression are still present in the September impression. Other characteristics have either disappeared or are newly acquired since the first March impression. When random characteristics such as the cuts in the shoe sole in Figure 10.15 change in their appearance, some possibilities are: 1 . they can still be directly and positively associated with the questioned characteristic,

in which case its value will not be affected or diminished; or, 2. they cannot be positively associated with the precise features of that characteristic, but could be a remnant of that characteristic and is in the same position in the shoe. Their value will be reduced accordingly depending on the degree of association that still exists; or. 3. They cannot be associated with the characteristic and will no longer have any value in the comparison; or, 4. A new characteristic may be present which was acquired between the time the questioned impression was made and the time the known shoe was seized. Although it would be ideal to obtain the suspect's shoes as quickly as possible after the crime's occurrence, obtaining the shoes months later does not always prevent the possibility of an identification. Some of the random identifying characteristics will usually survive and still be present on areas of the shoe, such as the area beneath the arch of the foot which normally does not receive much wear, or on entire shoes that, for whatever reasons, have not received much additional wear. 1have either worked or have been involved in cases where the shoes were not obtained until months or years after the crime. In one particular case, I 1/2 years elapsed prior to the recovery of the shoes and in another case, 9 months elapsed before recovery of the shoes. Yet in both cases, positive identifications were made, and many random identifying characteristics were still present on the shoe outsoles. In yet another case (Grimes, 1994), shoes obtained three years after the crime were identified with a crime scene cast of a shoe impression.

Toso, B. and Girod A., ''Evolution of Random Characteristics (Appearance and Disappearance)" First European Meeting of Forensic Science, Lausanne, Switzerland, September 1997.

356

Footwear Impression Evidence, 2nd Edition

(C)

(B )

(A)

Figure 10.15 Im p ression s from a sm a ll c e n ter portion of a rubber h eel of a sh oe, tak en in M arch (A), M ay (B), and S ep tem b er (C) of th e sa m e year. S o m e random ch a ra cteristics v isib le in M arch, alth ou g h slig h tly changed, are s till p resen t in Septem ber. O th er ch a ra cteristics have disappeared and still o th ers h ave been n e w ly acquired sin c e th e M arch im p ressio n . T h e sh o e w as w orn a lm o st daily.

Comparison of the Q uestioned Im pression w ith K nown Shoes

11

In his welcoming speech, while addressing the European Meeting for Shoeprint / Toolmark Examiners, Sybrand van Hulst’ comically stated Crim inal investigation w ould be m uch easier if every sh oe had a num ber in its sole, in mirror w riting... W ith every step the wearer w ould leave his num ber in the dirt, sand, blood, or grease... A bar code w ould be better still. A hand-held bar cod e scanner w ould be enough to d eterm ine w ho is the ow n er o f size 13, printed next to the broken w indow .

Obviously this suggested method of identifying shoes is in jest and is not a realistic possibility. Instead, certain methods and procedures of comparing questioned footwear impres­ sions with known shoes are used to effectively compare and conclude whether a particular item of footwear left its impression at the scene of a crime. Although protocols for this examination are written in many laboratories, they can only be general, and are useful to a point. Each case has its own evidence and circumstances and requires individual assess­ ment. Like any other forensic examination, much knowledge, as well as a good work ethic, must go into properly and fairly evaluating footwear impression evidence. Therefore, it is not the intention herein, nor is it believed possible, to list a step-by-step method that would be proper, thorough, and appropriate, for every examination conducted. Rather, this chapter addresses some basic information and concerns that an examiner might consider when both preparing and evaluating a case.

T rea tm e n t of th e E v id en ce Receiving the Q uestioned Im pressions When evidence is received, it is a good time to assure that all casts, negatives, lifts, and original impressions have been submitted. It is not uncommon to find that some contrib­ utors will make available only certain photographs and certain casts or lifts of the impres­ sions for examination. This can be for a variety of reasons. Some well-intentioned ' chairman of the Board of Chief Constables of the Netherlands, The Netherlands Police Institute, the Hague, the Netherlands (1997).

357

Footwear Impression Evidence, 2nd Edition

358 TITLE OF CASE JOHN SMITH - SUSPECT ALICE JONES - VICTIM RAPE/HOMICIDE 3/4/99

The below described evidence was recovered on M a rc h 4, Î 999, accom panied by a le tte r dated M a rch 9, 1999. QUESTIONED ITEMS: •

Q-1

Piece of glass bearing footwear impression



Q-2

Piece of carpel bearing footwear impression in blood



Q-3

Cast of footwear impression located outside broken window

Tw enty-four p h o to ^ a p h s a n d negatives o f fo u r separate bloody fo o tw e a r im pressions on flo o r, fu rth e r described as fo llo w s : •

Q-4

Footwear impression depicted in negatives 1-4.

Q-5

Footwear impression depicted in negatives 5-8 and 21.

Q-6

Footwear impression depicted in negatives 9-14.

Q-7

Footwear impression depicted in negatives 15-20,22, 23 and 24.

KNOWN ITEMS:

Shoes o f J O H N S M IT H , ob tained M a rch 4, 1999. •

K-1

Left shoe



K-2

Right shoe

F ig u r e 1 1 .1 An ex a m p le of a w o r k sh e e t c o n ta in in g a d escrip tio n of th e footw ear ev id en ce.

contributors believe they are helping the examiner by only selecting and submitting what they believe to be the best casts or photographs. In other instances, the contributor may not be aware of all of the evidence that was recovered and, therefore, may honestly omit it from submission. The examiner receiving the evidence should make some effort to assure that alJ of the impression evidence that has been recovered, is submitted for examination. This is also a good time to ascertain the date of the crime on which the questioned impressions were made. In some cases, there may be multiple scenes relating to one crime, and there may be a significant difference in the dates of each. Since other comparisons are likely to be performed on some of this evidence, appro­ priate considerations should be given to that possibility when the evidence is received. Examinations for soil, hair, fibers, glass, or body fluids precede footwear examinations. These exams should be completed or the necessary samples taken prior to the commence­ ment of footwear examinations. The evidence should be inventoried and a worksheet should be prepared that contains a description or listing of the evidence, the case title, date of crime, file numbers, and other basic information. The worksheet often constitutes the first page of the notes that are made during the course of the examination. A general example of a worksheet is featured in Figure 11.1. The examiner may wish to initial the evidence and place an identifying mark on each item of evidence that coincides with those used on the worksheet. Depending on what form the footwear impression evidence is in, i.e., casts, photo­ graphs, lifts, or the actual impression itself, certain steps will need to be taken to prepare the case for examination.

Comparison of the Questioned Impression with Known Shoes

359

Preparation of the Evidence Treatment of known shoes. Known shoes, like questioned impressions, are often submitted for other examinations in addition to the footwear impression comparisons. If they are to be examined for other evidence, such as hairs, fibers, glass, soil, and body fluids, these examinations must be considered first. The date on which the shoes were seized must be ascertained, since comparisons of known shoes that have been obtained months after the crime can reflect additional wear than existed on them at the time of the crime. The outsoles of the known shoes should be photographed with a scale. The photographs are convenient for noting important features during the examination as well as for providing a record of the shoe. They can also be used for court presentation. Original impressions. The best evidence is the original impression itself. Objects such as paper, pieces of tile floor, carpet, and numerous other items that contain the original impressions may require a variety of treatments to optimally record and enhance the impression. The treatment will depend on the surface, the nature of the impression, the contrast between the impression and the substrate, and whether it was a dry or wet impression when it was made. The original impression should first be photographed using a scale and the type of forensic photography that will capture as much detail and contrast as possible. In many cases this simply involves high-contrast and/or oblique-light photog­ raphy. However, the use of ultraviolet and infrared photography, as well as filters, alternate light sources, and specialized films, can often enable a forensic photographer to capture far more detail than is visible in the original impression. Additional treatment of original items of evidence after photography is discussed in Chapter 5. Photographs. Whenever examining a footwear impression in a photograph, it is pref­ erable to have the original negatives. If the original negatives have not been provided, you should insist on having them. There should not normally need to be an exception to this. If for some reason only photographic prints can be submitted, the contributor should include a natural size, full frame print of each negative. Natural-sized enlargements should be prepared directly from the original negatives and should be custom printed to best depict the footwear impressions in them. As previ­ ously covered in the chapter on photography, a natural size photograph is one in which the print is enlarged until the scale in that photograph equals its true size. A photograph of an impression having a 12-in. ruler next to it would be enlarged until the ruler depicted in the photograph measured exactly 12 in. If, for some reason, there is not a scale in the photograph, then a print, 8 x 10 in. or larger, should be made to allow the examiner to more easily evaluate the content of each exposure. The natural size prints should also be printed as a full frame print, if any footwear impressions contained in them run into the edges of those negatives. Figure 11.2A depicts a photograph that was submitted as evidence to be compared with the known shoes of a suspect. Figure 11.2B depicts a full frame photographic print of the same impression. If only the photograph in Figure 11.2A and not the negative were provided, the examiner would not have the benefit of the full impression to examine, nor would he or she have been aware of the other impression that was recorded on the film. Examination of original negatives assures the examiner of having all the evidence. There have been instances when valuable characteristics in the footwear impressions were overlooked because they were depicted on the negative's edge and were lost in the printing process. Once the photo-

Footwear Impression Evidence, 2nd Edition

360

(A)

•* .■»■•

*

'

I;;'.

-----— w - , ^

. ■ir:

__

"— -

(B )

xr«

7 Oia-r

vu 0 Ij

F ig u r e 1 5 .2 (contin u ed ) T h e L orenzo and Lyon sty le s, as sh o w n in th e Bruno M agli cata lo g (B).

(Figure 15.2B). Each color of both the Lorenzo and Lyon had a different style number. The Lorenzo and Lyon were expensive shoes. They both retailed for $160 a pair and were available in U.S. sizes 6 1/2 through 13. Mr. Grueterich advised that these shoes were first distributed in August 1990 and were officially discontinued in August 1992, with some shoes still being sold until early 1993. Two of these shoes, used for display, remained in his possession, one being a size 9 1/2 Lyon and the other a size 12 Lorenzo, both of which he furnished to me. Figure 15.3A depicts the Bruno Magli U2887 sole. Figure 15.3B depicts an impression of a Bruno Magli U2887 sole. A measurement of the length of the Bundy impressions indicated they were made by large shoes. In cases where a full or nearly full impression is left at a crime scene, a general estimate can be made of the shoe size. This is done from previously collected data from many brands of shoes and shoe sizes. However, if the manufacturer is known, sometimes a precise determination of the size of the shoes can be made. This depends on the method of manufacturing used and the availability of samples of pertinent sizes from the manu­ facturer. Mr. Grueterich put me in touch with Mr. Libero Lumi, the owner of Bruno Magli in Italy, who, in turn, put me in touch with SILGA. Both Mr. Lumi and the SILGA company were totally generous with their time and assistance. Through their cooperation, I quickly received a sample left and right sole for each European size 42 through 47. The soles below size 42 were so much smaller than the crime scene impression that they were not required for the examinations.. SILGA advised that the molds for the soles were made in Italy using the hand-milled method. Only 10 molds had been made, one each for 10 European sizes, ranging from size 38 to 47. Each of the design elements in the molds were identical in their dimensions. This means that a larger sole would contain more design elements than

436

Figure 15.3 T h e

Footwear Impression Evidence, 2nd Edition

(A) (B) Bruno M agli U 2 8 8 7 so le (A|. An im p ressio n of a right U 2 8 8 7 so le (B).

a smaller sole. It would therefore be possible and, in fact, easy to associate impressions made by one size and to distinguish impressions from the characteristics of soles of other sizes. In the laboratory, 1 made exemplar impressions of the size 42 through 47 soles, utilizing several different methods. Impressions were first made using an inkless method, which provided an ink-like black recording of each impression on white paper. Next, the soles were dusted with black fingerprint powder. The impressions of each sole were transferred both to a clear roller transport film and also to a clear adhesive material. This provided two transparent forms of examples. Series of impressions were also made in latex paint. All provided first generation impressions, some of which could be superimposed over natural size photographs of the crime scene impressions. Comparison between the known impressions and each of the size 42 through 47 soles confirmed that they were easily distinguishable, due to the different number of design elements on each size and due to the varying position of those design elements on each size. In preparation for the examination, natural sized photographs of each of the crime scene impressions were prepared. Then, each impression in the submitted crime scene photographs was compared with each sole and the respective exemplar impressions of that

The Footwear Evidence in the O. J. Simpson Trial

437

Figure 1 5 .4 T h e au th or su p erim p o ses a k n o w n im p ressio n over a q u e stio n e d im p ressio n during ex a m in a tio n of th e Bundy prints.

sole. In addition, the transparent exemplar impressions were superimposed over each questioned impression in order to show correspondence or non-correspondence. This method, shown by the author in Figure 15.4, allows for simultaneous comparison of all features in the impressions. At the same time, the crime scene impressions were clearly different, and did not correspond with the molded soles in the sizes 42, 43, 44, 45, and 47. These features were so clear and easy to demonstrate, that a trial chart, including a photograph of the entire shoe and a greatly enlarged area of a portion of the heel, was produced (Figure 15.5). In all instances, the bloody impressions on the Bundy walkway corresponded with either the left or right American size 12 (European size 46) soles. The occasional outer border, which was evident in some of the bloody shoe prints, occurred when the extreme outer edge of the sole, which was raised slightly off the ground, was placed under sufficient pressure by the wearer to make contact with the ground. This was easy to simulate in the inked and latex impressions. Mr. Grueterich provided a computer printout which listed when and where the size 12 shoes had been sold. This list showed that during the late 1990 to early 1993 period, only a total of 299 of the Lorenzo and Lyon styles, each of which had the U 2887 sole, were sold in a total of 40 stores throughout the U.S. and Puerto Rico. Although Silga and 4C had provided the necessary information and the samples from the molds of the larger sizes, I did not have first-hand knowledge of the entire process. As the date of my testimony drew near, anticipation of the sales transactions of O.J. Simpson’s purchase of the Bruno Magli shoes appeared increasingly possible. Legal objections to the admissibility of the molded soles that I received in the mail from the Silga factory were

438

Footwear Impression Evidence, 2nd Edition

F ig u r e 1 5 .5 O n e of th e m an y triaJ charts used in th e crim inaJ and civiJ trials. T h is chart ilJustrates th e visuaJ d ifferen ces b e tw e e n th e p o sitio n of th e d esign on each size.

also anticipated, even though the evidence was admitted in every other case I had experi­ enced. Further, the defense might object to the entire sizing issue if 1 had not witnessed the process first hand. Consequently, it was decided that 1 should travel to Italy and visit these factories to witness the production of this shoe and resolve any questions that might be pertinent regarding sizing. On January 23, 1995, I flew to Pisa, Italy, and then, accom­ panied by Mr. Lumi, traveled to Civitinova Marche, Italy. There, at the SILGA factory, I had the opportunity to ask questions that related to the manufacture of the molds, whether any had ever been repaired or replaced, how frequently they were used, and so forth. I was able to examine the 10 molds used for this design, as well as the different name slugs used for the Bruno Magli and Lord brands. I obtained a pair of size 12 soles which they molded for me. We then traveled to the nearby 4C factory, where the size 12 soles that were just made were used to produce a finished shoe. The 4C factory only produced high-end footwear. At that factory, they utilized high quality leather, which they cut into various pieces to form the shoe uppers. The uppers were sewn and built around a last, which had an insole board tacked to it. The insole board and the portion of the uppers were stretched around the bottom edges of the lasted shoe, and were then roughed-up in preparation for the adhesive. Adhesive was added to the inner surface of the U2887 rubber sole and to the roughed bottom of the lasted upper. The adhesive on each part was heat activated. The sole and upper were then attached to each other. Stitching was then added in a groove around the edge of the shoe. In the 4C factory the same green-colored lasts used in the original production of the Bruno Magli Lyon and Lorenzo shoes were again used to make a mock-up shoe of the size 12 Lorenzo. The lasts on which these shoes were built were made using the American sizing system, and actually had U.S. sizes printed on them. The left and right lasts used to build the American size 12, one of which is depicted in Figure 15.6A, had a “ 12” printed on it. Next to the printed American size 12, and written in handwriting with a red marking pen, was the European size equivalent “46”. In other words, 4C equated a size 46 European size with a U.S. size 12. The 4C company was producing

The Footwear Evidence in the O. J. Simpson Trial

439

(A)

(B)

SIZES OF SOLES SIZES OF LASTS

38

39

40

41

42

43

44

45

46

47

6- 1/2 - 7

7- 1/2

8 - 8- 1/2

9 - 9- 1/2

10

10-1/2 - 1Í

11- 1/2

12

13

Figure 15.6

A siz e 12 Last, used to m a k e th e siz e 12 Bruno M agli sh o es. It w o u ld a lso he used to m ake a European siz e 46 sh o e (A). T h e siz e co n v ersio n chart used in Italy, w h ic h eq u a tes European and A m erican siz e s (B).

high quality shoes, including the Bruno Magli shoes. According to their explanation, the American sizing system was used to produce their lasts, since it offered more size combi­ nation choices and flexibility than the European sizing system. This, in turn, allowed them more flexibility in producing the exact fit they were trying to achieve in their shoes. 4C explained that this was done since it provided them more dimensional choices than lasts produced on European sizing systems. It was important to them, when producing highend quality footwear, to provide the best fit. Mr. Lumi and the 4C company provided a conversion chart. This chart, featured in Figure 15.6B, shows the relation of the European sizes to the respective American sizes. Mr. Lumi advised that the size 12 and size 13 shoes were primarily made for the U.S. market. These sizes were not commonly sold in Italy, where the average sizes of footwear are smaller. My prior experience with the footwear industry had enlightened me to exceptions that were occasionally made by some manufacturers when shoe uppers were combined with adjacent sized soles. In other words, could a size 11 or 13 sole be used on the size 12 shoes, or could a size 12 sole be used on a size 11 or 13 shoe? I insisted on full information and an explanation concerning this possibility. According to personal discussions with the owner and shoe fitters at the 4C company, as well as with Mr. Lumi, this conversion chart was strictly adhered to without exception. They explained that they would never substitute a different sized sole for the upper, other than what was indicated in the conversion chart. I reiterated to them that I had personal knowledge that some factories, making shoes of lesser quality and price, had occasionally taken soles at the end of a day’s production, and used them on adjacent sized uppers in order to be less wasteful. 1 asked repetitively if, under any circumstances, this was possible at the 4C company. It was clear, after discussing this with Mr. Lumi and the owner of the 4C factory, that this practice would never occur at 4C. There was an intense devotion here to quality, at any cost, and there was also intense pride in the manufacturing of their quality shoes. The size 12 Bruno Magli soles were produced only on the lasts that were marked American size 12 (European size 46).

440

Footwear Impression Evidence, 2nd Edition

In addition to locating the source and size of the Bruno Magli shoe prints, there were additional requests made regarding other footwear impression evidence or issues. Some of these were conducted in Los Angeles, while others were conducted in the FBI laboratory. I examined a pair of white Reebok athletic shoes which O.J. Simpson stated were the shoes he was wearing the evening of June 12, 1994. He had provided these to Detectives Tom Lange and Phil Vannatter. The shoes were obviously not the design of the Bruno Magli prints, but were useful as a standard of the shoe size O.J. Simpson wore. The Reebok shoes contained a sizing label which identified them as U.S. size 12. Although the Reebok was an athletic shoe and the Bruno Magli was a dress casual shoe, they were both manu­ factured in identical ways, with both having a compression molded cup sole. The exterior sole dimensions of O.J. Simpson’s Reebok shoe were identical to the American size 12 Bruno Magli Lorenzo shoe which remained from the original shipment, and which had been provided by Mr. Grueterich. Additionally, the interior dimensions from the heel to the toe were virtually identical in both the Reebok and Bruno Magli with, at most, an insignificant 1 to 2 mm variance. For elimination purposes, photographs were submitted to me of the footwear of police officers and detectives who were present at the Bundy scene. The early arriving officers were immediately aware of the bloody shoe prints, and therefore avoided stepping on them. Bloody impressions such as those on the walkway would coagulate and dry within minutes after they were made. Had any police officers tracked over the impressions, they would not have harmed or changed them in any way. The possibility did exist that some pooled blood, or blood beneath the victims, could still be moist enough for someone to track through and then leave impressions. Had this occurred, an additional set of shoe prints would have been present. None of the police officers was wearing a $160 pair of Bruno Magli shoes and, as expected, none of the elimination prints of the officers were of the Bruno Magli design. The white envelope that held the eyeglasses which Ron Goldman was returning to Nicole Brown Simpson contained a partial Bruno Magli design on one end. The envelope was covered with blood splatter and also contained a very small print on the opposite end. The dimensions of this print, shown in Figure 15.7, were approximately 1/2 in. x 1/2 in., or about the size of a drop of blood. The pattern was not that of a shoe print. It reflected no design border, such as from the edge of the sole or heel. It also reflected a very fine pattern that, by virtue of its size and features, was not a footwear design. The pattern consisted of jagged lines, running parallel to each other, and only l/16th of an inch apart. Small patterns or texture that are often present on footwear soles are created through hand stippling or acid etch texturing. These methods were previously discussed in Chapter 7. In order for this pattern to be hand stippled, the pattern on the steel dye would have to be very small and the operator would have to carefully and repetitively strike the die to create that pattern. This would not be economical, nor would the steel die have such a small pattern for that purpose. Any pattern of that size would be represented in a cluster on the end of the steel die and would be used to cover an entire area. It would not just be applied as a singular design in rows. Nor were the characteristics of the pattern on the envelope those which would be reflected in an acid-etch pattern. These patterns are also discussed in Chapter 7 and are characterized by their uniformity and their separation from one another. In addition, if a shoe had made this impression, there would possibly be a squeegee effect evident where the pressure of the shoe squeezed the blood to the sides of the pattern. There would also likely be surrounding residue impressions or depressions on

The Footwear Evidence in the O. J. Simpson Trial

441

F ig u r e 1 5 .7 A portion of th e e n v e lo p e th a t Ron G old m an carried on ju n e 12, 1994, bearing a smalJ bloody pattern w h ich transferred to the e n v e lo p e from h is jeans.

the paper, representing where the non-bloody portions of the shoe struck the envelope. None of these other characteristics were present. No further examination was made by me at this time, since it did not represent a footwear impression. In reviewing the hundreds of photographs that were taken at the Bundy scene and O.J. Simpson’s residence on Rockingham, 1 located some photographs which showed a trian­ gular piece of paper adjacent to the head of Nicole Brown Simpson. 1 requested the original paper; however, it was never recovered. The original negatives were used to make enlarge­ ments of this piece of paper. The paper, which was triangular, but only approximately 4 x 6 in. at its largest dimensions, was largely blood-soaked, but did reflect a very fine pattern in a small portion of it. This pattern was similar to the pattern on the end of the envelope. For the same reasons as mentioned previously, this pattern was not considered a footwear impression. The carpeting from the driver s side of O.J. Simpson’s Bronco had been removed. It contained some stains which were believed to be bloody shoe prints. DNA tests linked the blood to both victims. Other blood drops on the carpet were linked to O.J. Simpson. The chance was also possible that the carpet contained latent bloody shoe prints that could be developed though chemical enhancement. I was requested to travel to Los Angeles and chemically process the carpet and photograph it. This was done on September 1, 1994, in the presence of two defense experts. The carpet was first treated with a fixative. It was then

442

Footwear Impression Evidence, 2nd Edition

processed with luminol, followed by leuco crystal violet. As a result, the existing traces of blood were further developed. The blood pattern was most likely a result of the Bruno Magli shoe transferring some blood from the recessed areas of its design. The pattern contained some fragments that were similar to the shapes of the grooves between that design; however, they were too limited and incomplete to reach any positive association with the Bruno Magli design. It would have been highly significant to have been able to positively identify the Bruno Magli design in O.). Simpson’s vehicle. However, common sense would tell anyone that a shoe, even after tracking through a considerable amount of blood, would not have any blood remaining on the raised areas of the shoe sole after walking over 100 feet to a vehicle. That was the distance to the area outside the rear gate, where a vehicle would have been parked. Any blood that remained beneath the shoe would only have remained in the grooves between the shoe design elements. Blood in those areas did transfer to the carpet, but not to the extent that the design was recognizable. The blood-soaked blue jeans that Ron Goldman was wearing were examined to see if they contained any footwear impressions. They were photographed in color. They were then photographed with black-and-white film and a blue filter. The filter lightened the blue color of the jeans and darkened the red color of the blood. This allowed for the blood stains to appear darker against a lighter background. One Bruno Magli heel impression and one other partial impression of the Bruno Magli design were present on the right leg of the jeans. These impressions were very partial and, because of the absorbent nature of the cotton jeans, had been partially dispersed, lessening the detail. Many other partial marks were present on the right pants leg. None of these were characteristic of footwear impressions. Ron Goldman’s light colored Pataugas boots were size 44 (U.S. size 11). The fabric uppers of one were heavily blood stained. The Pataugas boot design was clearly different from the Bruno Magli design. No impression of the Pataugas boots were present at the scene. Nicole Brown Simpson’s black dress contained a partial heel impression. The impres­ sion was on the front of the dress. It was photographed with infra-red photography, which lightened the black dress color, improving the visibility of the blood stain. The impression was very partial and limited in detail. What detail was present did correspond with the contours of a portion of the left heel of the Bruno Magli U2887 sole. At the autopsy, some color photographs had been taken of the back of Nicole Brown Simpson. The photographs depicted a reddened mark, which had the appearance and characteristics of a contusion. Depending on the amount of force involved and the damage to the underlying tissue, contusions can range from those that are virtually invisible to those of extreme discoloration. The mark on Nicole Brown Simpson’s back was not an abrasion, which involves a scraping of the skin and has an altogether difference appearance. Neither was the mark the result of lividity, a settling of the blood as a result of gravity. Nor did it conform to any mark, indentation, or impression as a result of the movement or position of her body, or the post-mortem contact of her body with another object. I was asked to examine the mark on her back to determine if it was a shoe print. I shared the photograph with a forensic pathologist from the Armed Forces Institute of Pathology in Washington, D.G. He concurred that it was a contusion and utilized a computer enhance­ ment program to improve the visualization of the impression. 1 determined it contained contours that were not unlike the contour and general size of a portion of the heels of the Bruno Magli U2887 soles. The smooth contours of the contusions were from a man-made

The Footwear Evidence in the O. J. Simpson Trial

443

I

‘ i' F

I

Figure 15.8 T h e

Bundy w a lk w a y w as so lid co n crete, but m ade to lo o k as if it w ere c o n stru cted of individual tile s. T h e arrow at th e top p o in ts to th e area w h ere th ree (3) Bruno M agli footw ear im p ressio n s face across th e w a lk w a y in th e sa m e d irection as th e arrow. T h e sm a ll tree and shrubs to th e right w o u ld have provided a p lace to hide and m ay exp lain w h y th e prints are facing in th a t d irection .

object, such as the edge of a heel, as opposed to irregular edges or contours found on natural objects. The fact that the size and contour in that mark corresponded with the edges and corner of the heel of a test impression of the Bruno Magli shoes supported the distinct likelihood that the Bruno Magli shoe had, at one time, come into contact with Nicole Brown Simpsons back. But a more detailed and conclusive comparison was not possible, given the limited features. I examined a photograph of O.J. Simpson and his daughter, taken in the late afternoon of June 12, 1994, at his daughter’s recital. The photograph depicted him wearing sandals. The sandals did not have the same appearance or sole profile as the Bruno Magli design and were eliminated. While in Los Angeles, I visited the scene at 875 S. Bundy Drive. The walkway alongside the condominium was made of concrete. Shown in Figure 15.8, the concrete was made to appear as if it was a sidewalk constructed from individual tiles. This was done by pouring the concrete, and then, as the concrete began to set, impressing a grid design over and into its surface. With the grid in place, a coloring agent was then added to the exposed areas of the concrete. The areas beneath the grid were indented about 1/4-in. Because they were covered by the grid, they were not contacted by the coloring agent and, therefore, retained the original concrete color. Even though the entire walkway was concrete, when the grid was removed, the final appearance simulated that of a walkway having lightly colored tiles surrounded by a lighter concrete color grout.

444

Footwear Impression Evidence, 2nd Edition

_______ ___

n h • I l >'

i

‘ / __________

^1

Figure 15.9 A portion of o n e of th e trial charts, d ep ictin g th e Bundy w alk w ay, th e p o sitio n s of th e v ic tim s, and th e sh o e prints h eaded tow ard th e rear gate. I prepared a diagram of the position of each shoe print. To do this, I located the position and direction of all of the impressions on the Bundy walkway. Figure 15.9 depicts the front gate area, and some of the shoe impressions headed away from the victims and toward the rear gate. Due to their features and proximity to one another, it was clear that there were two sets of bloody Bruno Magli impressions on the walkway. The impressions were left by one individual who proceeded down the walkway to the point at or beyond where the blood was worn from their shoes and was no longer leaving visible impressions. For whatever reason, the individual returned to the bloody portion of the walkway. On the steps next ot Nicole Simpson s body are two very faint impressions, representing blood pressed from the edges and depressed areas of the shoe. One of these impressions faces toward the front gate, while the other faces toward the rear gate. These very light impres­ sions, representing in part blood that was deposited from the edges of the design elements and the grooved areas of the Bruno Magli design, were likely made when the perpetrator returned to the front gate area. After returning to the bloody scene, his shoes again tracked through the heavy blood. As he exited for the second time, toward the rear gate, his shoes left another set of tracks on the walkway. Since none of the bloody impressions touched each other, it was never possible to determine which set occurred first. Both sets of tracks eventually faded away after several steps, as the blood was worn from the raised areas of the soles. But beyond that point, there was still some footwear evidence. That evidence consisted of the blood on the edges of several steps towards the rear gate. Even though the blood had been worn from the raised surfaces, the shoes still contained blood in the grooves and depressed areas between the design elements. When the shoe curved around the edge of the steps, some of that blood was squeezed off and deposited. These deposits of blood were not detailed impressions that reflected the design, but were simply deposits of blood. At the rear step of the walkway, there was one partial blood impression that did not reflect the edge of the raised design of the shoe, but which occurred when small amounts of blood were forced from the crevices of the shoe.

The Footwear Evidence in the O. J. Simpson Trial

445

At one particular area, about 30 feet down the walkway from the victims, there are three impressions that face a different direction. These impressions labeled L, M, and O in Figure 15.9, were located just beyond a small tree and were facing toward the house instead of directly toward the rear gate, as all of the other impressions were. The position of these impressions indicated that the perpetrator stopped or turned around at this point. X-

M-

X-

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The fact that only 299 size 12 shoes had been sold at 40 stores suggested it might be possible to link the sale of these shoes to some of the buyers. During the investigation, attempts were made to link the purchase of one of the 299 pairs of Bruno Magli shoes to O.J. Simpson. Unfortunately, the investigation at these 40 stores met with some difficulty. First, nearly every store had changed their skew numbers or computer systems since 1991 and 1992, when they sold these Bruno Magli shoes. Second, through the overall investi­ gation of O.J. Simpson, it became apparent that O. J. Simpson usually purchased items with cash and not with his credit cards. Cash transactions could never be traced. The efforts to connect O.J. Simpson with the actual purchase transaction of the Bruno Magli shoes was never successful. Interestingly, one of the 40 stores that carried these shoes was Bloomingdale’s of New York. A salesman from this store, who later testified in the criminal trial, recalled at least five occasions when he sold O.J. Simpson a pair of size 12 shoes. Although the salesman could not recall the specific sole designs of those shoes, it was noted that Bloomingdales had carried this Bruno Magli design during that period of time, including the Lorenzo in the color black. The significance of this will be addressed later in the discussion of the civil trial.

It is common for manufacturers to créa e molds for shoe soles, which have interchange­ able name or logo plates. This allows the manufacturer to use the same molds for more than one customer, by using more than one name in the mold. The interchangeable name plates can be any shape, but they are most commonly oval or rectangular. This was the case with the U2887 soles samples. When 1 received the samples from SILGA, I noticed there was an oval shape in the arch area of the sole where the brand name would appear. One of the molds, shown in Figure 15.10 with the oval slug bearing the name Bruno Magli resting on it, depicts how those slugs are changed. The sole samples I received shared three different names. One of these, of course, was the Bruno Magli name. The other soles contained either the name LORD, or the Italian words, ANTICA CUOIERIA. ANTICA CUOIERIA is not a brand name, but when translated mean something like “maker of fine footwear”. The interchangeable inserts having the words ANTICA CUOIERIA were only produced for one mold size, since they were only used for samples. The name LORD, however, was a name used on other soles molded and sold by SILGA. I believed it was important to determine if there was a possibility that this same sole design, possessing the name LORD, was being sold in the U.S. These names, located just in front of the raised heel, are held off the ground and do not record in an impression on a hard surface. None of the Bundy impressions revealed any impression from this area of the shoe. This meant that, based upon the information provided by the crime scene impressions, the soles (and shoes) could not be limited to only those bearing the Bruno Magli name, but could have

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F ig u r e 1 5 .1 0 A c lo se-u p lo o k at o n e of th e U 2 8 8 7 m o ld s, w ith th e oval slu g bearing th e n am e Bruno M agli rem oved and restin g on th e m old .

been made by shoes having the LORD name, if any of the LORD shoes had been sold in the U.S. SILGA, once again, was very cooperative in providing the names of the shoe companies who purchased the soles manufactured with the LORD name. Although the total sales of the LORD soles was relatively small, it was still necessary to contact approximately 20 shoe companies who had made shoes with those soles, to determine if they had exported any of the LORD shoes to the U.S. With one exception, all of the LORD soles were sold to other Italian shoe manufacturers who used the soles to make and sell the shoes exclusively in Italy. The exception was one company in Ireland; however, they also advised that they did not export any shoes with that Silga sole to the U.S. Also contacted was the U.S. representative for SILGA, who confirmed that no other shoes were ever sold in the U.S. with the U2887 soles, except the Bruno Magli Lyon and Lorenzo styles. I was called to testify regarding the results of my examinations. The first day of my testimony was on June 19, 1995. As was the case with many of the scientific witnesses, I was first requested to provide some basic information to the jury regarding the type of work a footwear examiner performs. This involved describing the process of determining the brand name or manufacturer, the comparison of questioned impressions with shoes of suspects, and the variations that can exist between the molds used to make soles. I also explained to the jury what occurs when a person walks over a wet, blood-soaked surface. This involved illustrations that darker impressions will be left initially, with the following impressions becoming lighter and lighter until there is insufficient blood to leave a visible print. My testimony then covered the examination of each impression on the Bundy walkway, and my conclusions that the impressions corresponded with either the left or right size 12 Bruno Magli soles. This was followed by testimony regarding the other

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examinations I had performed, namely those on the envelope, dress, shoes, jeans. Bronco carpeting, etc. Numerous large charts were used to graphically present this information to the jury. One of those charts, the first to be used during my testimony, was a very large picture of the Lyon and Lorenzo styles, as well as the U2887 soles. It was hoped that the news coverage, which filmed the charts, might result in producing witnesses that remem­ bered seeing O.J. Simpson in the shoes, or perhaps the salesman who sold O.J. Simpson the shoes. My direct testimony lasted half of the day. F. Lee Bailey, one of the defense attorneys, provided my cross-examination. Some of his questions were routine and anticipated. They included questions which inferred or explored the possibility that the LAPD did not recover the footwear evidence properly or thoroughly. I testified that the LAPD did an excellent job taking examination quality photographs of the impressions. They photographed them both in black-and-white, and in color, always using a scale and tripod. All of the photo­ graphs were in focus, were labeled, and were of value for examination. Bailey insisted that other impressions should have been present, either in the soil or other areas of the scene. Since I was not actually present at the scene on June 13, 1994, I could not testify that impressions were or were not in other locations. However, I had reviewed the photographed soil areas of the scene. When I viewed those areas at later trips to Bundy, there was nothing to suggest an expectation that impressions would be retained in that soil. The soil was packed and was filled with much organic material, such as plant debris and mulch. At the time I visited Bundy, the soil was not conducive to retaining the impressions of shoes. Further, there was considerable testimony of first arriving officers, who used their flash­ lights in the dark to look for any impressions in the soil, particularly around Ron Goldman’s body. They had also looked for other impressions in and out of the condominium. None were located. Bailey’s cross-examination continued with questions about the percentage of persons who wore size 12. I had already testified on direct that over 9% of the shoes sold world­ wide were size 12. I was in no way inferring that only Simpson could wear that size. Bailey continued with his theory of how he believed it was possible that two persons, each wearing size 12 Bruno Magli shoes of identical designs, left the impressions. The front gate area of the Bundy walkway, adjacent to the victims, was covered with blood. The impressions that originated from that area consisted of the normal range of dark to light impressions that would be expected. The number of left and right impressions and their close proximity, as well as certain features of each, indicated that two sets of shoe prints were leading from the victims and headed toward the rear of the condominium. But all of these bloody impressions were from a size 12 U2887 SILGA sole design used on the Bruno Magli shoes. The limited sales (299) of the size 12 shoes over a 2 1/2-year period meant that the 40 stores which carried these shoes normally only stocked one pair of size 12 shoes at a time. This was confirmed by computer printouts which recorded the style, size, date, and store each pair of shoes was shipped to. The likelihood that two persons, both with a size 12 U2887 sole design, committing this crime side by side simply did not exist. For this to have occurred, there would have had to be two perpetrators, both who coincidently wore a size 12 shoe. First, one would have had to select the rare Bruno Magli design and purchase the shoes. Then the second perpetrator, would have had to either special order the second pair of shoes (which would have been evident in the computer printouts), or to travel to one of the other 40 stores that carried one of the other size 12 shoes. This was a ridiculous notion that was being raised by Bailey, to which I simply stated

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did not happen. Further, if two individuals were going to obtain footwear for the specific purpose of committing a crime, after which they would dispose of the footwear, it would make more sense for them to purchase a common pair of inexpensive shoes. They could easily obtain two pairs of a common shoe in size 12 without raising any suspicions. They would not buy expensive shoes that were rare. Bailey also challenged my observation of the three impressions that were turned in a different direction, and the notion that they possibly represented a place where a single perpetrator may have hidden before returning to the front gate. He argued that this area of the walkway was in plain view of anyone walking past the condominium. Figure 15.8 depicts the walkway and the area, marked with an arrow where the three impressions were located. Figure 15.9 is a drawing of the walkway. The street and sidewalk are a considerable distance outside the front gate, an area that was heavily covered with trees and vegetation. In addition, the darkness, total distance, the front gate itself, and the elevation differences between the street area and the area at that point on the walkway made it a very secluded place to hide. X-

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Charles V. Morton, a criminalist with experience involving footwear examinations, represented the defense and was in court for my testimony. He never testified and, as far as I know, never disagreed with my findings. In spite of Judge Ito s requests and the defense’s obligation to produce reports and notes of its own experts, little was known about who, if anyone, would testify to any matter about the footwear impressions at the Bundy scene. On the other hand, whenever 1 or Special Agent Doug Deedrick prepared our FBI reports, they were mailed directly to judge Ito. Judge Ito had ordered this. When he received these items, he would then turn them over to the respective prosecution and defense teams. The Simpson defense teams and presumably their experts, therefore, had an original copy of every photograph and report. They also received over 200 pages of my notes. For the matters concerning the footwear evidence, the defense produced Dr. Henry Lee, then the director of the Connecticut State Crime Laboratory. Dr. Lee had become involved very early in the case. Reportedly, he had been retained by the defense and had flown to Los Angeles on June 15, 1994, before O. 1. Simpson had even been formerly charged with the homicides. On June 25, 1994, over 12 days after the victims were discov­ ered on the Bundy walkway, he visited the Bundy scene. Photographs taken by Dr. Lee or under his supervision at that visit were enlarged and later used by the defense as exhibits to support his testimony about “imprint evidence.” ' Not long before his testimony, I was shown a page of notes taken by or for Dr. Lee, which referred to his observations when he visited the Bundy scene on June 25. The notes were very brief and contained few to no supporting details. In them were brief references to “parallel lined imprints” on the Bundy walkway, the envelope, and the jeans of Ron Goldman. Also provided were poor quality, 4” X 6” photographs taken on that date. The photographs revealed a curved metal tape measure that was used as a scale. They were not taken on a tripod and had been printed extremely dark, as if to emphasize every mark or stain on the walkway. The photographic quality was so poor, we speculated that the defense may have provided us with photographs of photographs.

*Dr. Lee defined two-dimensional footwear impressions as 'fimprints" and three-dimensional impressions as "impressions."

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When Dr. Lee testified, he did not contest any of my findings regarding the size 12 Bruno Magli impressions. But he did testify considerably about what he referred to as other “imprint” evidence at the Bundy scene. The defense had prepared numerous enlarge­ ments of the “imprints” in court. These enlargements were from a combination of pros­ ecution photographs taken at the crime scene on June 13, as well as Dr. Lee’s photographs, taken on June 25, 1999. From these enlargements. Dr. Lee was asked to point out various “parallel lined imprints.” These included those on the envelope (Figure 15.7) and a trian­ gular piece of paper, which Dr. Lee stated contained parallel lined imprints, possibly from a shoe. From another photograph he testified about parallel line imprints on the edge of a tile in the walkway (Figure 15.12). He later conceded that he could not eliminate the possibility those imprints were defects in the concrete. From another photograph, taken on June 25, he pointed to an imprint that he described as parallel lines that might be a shoe print. When shown photographs of the same tile, taken on June 13, which revealed no imprint, he explained that blood darkens with age, and therefore this light imprint may not have originally been visible. Dr. Lee also testified that the parallel line marks on Ron Goldman’s jeans were not from Goldman’s clothing but were possibly caused by footwear. With regard to all of the aforementioned “parallel lined” imprints, it is interesting to note that the specific size and spacing of these so-called parallel lines were different, with each occurring only once. Hank Goldberg, the prosecutor who cross-examined Dr. Lee, felt that Dr. Lee’s testi­ mony of multiple parallel line imprints was confusing and misleading. Was the defense team simply using Dr. Lee to point out patterns or marks that were insignificant and having him admit he could not eliminate them as possible shoe prints? Over and over again, the defense would ask Dr. Lee questions like, “could it be an ear print, could it be a nose print, could it be a Bruno Magli print, could it be a ...?” Even though in most instances. Dr. Lee would not absolutely say the “imprints” were shoe prints, the method of questioning by the defense combined with Dr. Lee’s answers left the only remaining logical choice as a shoe print of a design other than the Bruno Magli shoe. Or was Dr. Lee intending to infer that there could be several other persons at the crime scene, each having a different parallel line pattern on their shoes, and each leaving only one impression, as if they were otherwise flying around the scene? All of this, while somehow, a person, wearing size 12 Bruno Magli shoes, left two clear sets of bloody impressions on the walkway. The prosecution was certain that no other shoe prints were present at the Bundy scene on June 13. They were also certain that Dr. Lee’s testimony raised more questions and resolved none. Experts are supposed to examine evidence and reach their conclusions based on sound, demonstrable evidence. They are supposed to testify to their observations and opinions, to help clarify issues at trials, not confuse them. The prosecutors requested that I and Special Agent Doug Deedrick prepare for the rebuttal of Dr. Lee’s testimony. This required some additional study and examination of Dr. Lee’s photographs. I re-examined the very small impression on the end of the envelope that Dr. Lee had referred to as an “imprint.” I did not believe this was a footwear impression, but was now attempting to determine what actually caused the impression. I recalled the brush marks on the Bundy concrete walkway. Brush marks are placed on concrete by dragging a broom or brush across the surface just before the concrete hardens. When this is done, it creates very close parallel lines. I wondered if a drop of blood on that surface, when contacted by a falling envelope, could have transferred the brush mark pattern from the concrete to the envelope. I requested that enlarged photographs be made of the walkway tiles where the

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envelope was found. At the same time, I noticed the impression also had a design Like the warp and weft of woven fabric and considered the possibility that a drop-size area of blood on Ron Goldman s jeans was contacted by the envelope while still in Goldman’s hands. 1 also re-examined the parallel line patterns on the jeans of Ron Goldman, which Dr. Lee referred to as ‘"imprints.” None of the “parallel line imprints” that Lee had testified to contained any border representative of the edge of a heel or sole. Nor did they have the variety of dark to light impressions, which occur when a shoe sole, unevenly covered with blood, repeatedly stomps a victim, leaving heavy impressions first, followed by lighter and lighter impressions. Rather, the parallel line “imprints” were all very light and partial. Additionally, some of the parallel lines were curved slightly. A shoe sole is rigid and will, upon contact, quickly force the material or skin of a victim to conform to its rigid flat bottom and to the features of its design. A shoe sole with a parallel lined “imprint” would leave a consistent impression, even if only a partial one. It would not leave one that is straight, then another which is curved. On the other hand, when something like fabric, which is not rigid, transfers its pattern in the form of an “imprint”, the pattern normally varies in the pattern transfer process. The parallel lines on Ron Goldman’s jeans bore remarkable similarity to the parallel lines of his blood-soaked corded shirt that he was wearing. 1 referred both the envelope “imprint” and the jeans “imprint” to Special Agent Doug Deedrick, who had already performed many hair and fiber examinations in this case. He examined and took test impressions of both Ron Goldman’s jeans and shirt. This is a necessary process when making comparisons of this type, as the specific way in which a fabric will print can only be determined by making test impressions of that fabric. Deedrick concluded and testified that the parallel line pattern made by test impressions of Goldman’s jeans, corresponded with the small patterned impression (“imprint”) on the envelope and triangular piece of paper. He also concluded and testified that the test impressions of the parallel line cord patterns on Goldman’s shirt corresponded with the fragmented parallel line patterns (“imprints”) on parts of the right leg of Goldman’s jeans. In other words, Goldman’s bloodied shirt had transferred its parallel lined pattern to his jeans. In addition and separately, the pattern of his jeans had transferred a drop size “imprint” to the envelope he once carried. One of the photographs of a tile at Bundy, which was taken on June 25, 1994, and produced by the defense in court, is featured in Figure 15.1 lA. In the corner of the tile Dr. Lee’s testimony described a parallel line imprint, possibly a faint bloody shoe print, which he alleged may have gone unnoticed on June 13, yet 12 days later, on June 25, had darkened and was now visible.^ In the June 25 photograph (Figure 15.1 lA) the parallel lines appear on the right corner of the tile (right arrow). This photograph, as provided by the defense, was of very poor quality and had been printed very dark. Because this partic­ ular tile also had a Bruno Magli impression on it, it had been photographed by the LAPD on June 13. 1 reviewed the photographs taken by the LAPD on June 13, featured in Figure 15.1 IB, which include the same tile as featured in Figure 15.1 LA. The tile in that area was clean in the June 13 photograph and there was no evidence of the so-called “imprint” which Dr. Lee had referred to on the June 25 photograph. Two arrows in Figure 15.1 IB had been my experience, without exception, with both crime scene impressions as well as the thousands of impressions I have prepared for classes, that faint blood impressions quick]y fade and become lighter with age, and often become latent. They do not darken. Heavier deposits of blood, such as those in pooled areas, do darken with age.

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F ig u r e 1 5 .1 1 A photograph taken of a portion of th e Bundy w a lk w a y by or for Dr. H enry Lee on June 25, 1994, 13 days after th e h o m ic id e (A). T h e w avy parallel lin e print (top left arrow) is an im p ression in th e actual co n crete, o b v io u sly form ed years prior. T h e parallel lin ed m ark on th e right (low er right arrow) w as n ot presen t in photographs taken June 13, 1994. A p h o to ­ graph taken by th e LAPD on June 13, 1994 (B). T h e top half of photograph B is of th e sa m e tile as th e b ottom half of th e tile in photograph A. N o te (1) th e b o tto m arrow, w h ich p o in ts to th e edge of a Bruno M agli heel print; (2) th e right arrow, w h ich p o in ts to a dark spot; and (3) th e top left arrow, w h ich p o in ts to th e edge of th e Bruno M agli h eel print in th e cen ter of photograph A. N o parallel m arks w ere p resent in th e low er right corner of th e tile on June 13, 1994.

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Figure 15.12

ParalJeJ lin e s su ch as th e se w ere p hotographed and offered as parallel lin ed imprints'" during th e te s tim o n y of Dr. Lee. T h ey are p resen t all over th e Bundy w alk w ay, as th ey are trow el m arks in th e co n crete, p u t th ere w h en th e co n c r e te w as laid.

point to the edges of two Bruno Magli heel prints, and the third arrow, on the right, to a dark spot or stain, possibly from crushed berries which were present on the walkway. These same three reference points can be seen in Figure 15.11 A; however, the “parallel line imprint” does not exist. I also testified regarding two other “imprints” about which Dr. Lee had testified. One of these consisted of a shoe print having a parallel, but wavy or wiggly design which is depicted by the left arrow in Figure 15.11 A. Another consisted of a few parallel lines on the edge of one of the simulated tiles (Figure 15.12). During my return to the Bundy walkway, I located the exact tiles in these photographs. The parallel lines on the edge of the tile (Figure 15.12) were actually trowel marks in concrete, used to finish the concrete when it was poured years prior. These were present on many tiles on the Bundy walkway.

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The wavy “imprint” was, in fact, a shoe print; however, it too was in the concrete, and was made before the concrete walkway had hardened. Neither had any significance to the homicides in this case, yet the defense made enlarged exhibits of these and displayed them to the jury. One other parallel line shoe print that Dr. Lee had photographed on June 25, was in fact a shoe print. This impression was dark in color. It was an isolated shoe print, located some distance from the victims. It did not appear in the photographs taken on June 13. I testified on rebuttal on September 14, 15, and 18 regarding my opinion of these issues and was cross-examined by defense counsel Barry Scheck.

In the following weeks, I received several pictures of O.J. Simpson, taken by persons at various football games. Some of them showed him wearing lace up shoes, having a leather upper and synthetic sole, which were similar in appearance to the Bruno Magli shoes. None of them were of Simpson wearing the Bruno Maglis. The trial ended in an acquittal. X- X-

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Prior to the opening of the homicide trial, a “wrongful death suit” had been filed against O. J. Simpson, by the Goldman and Brown families. The civil trial was now scheduled and would be held in Santa Monica, California. The plaintiffs in the case requested the FBI to allow Doug Deedrick and myself to provide the same testimony in the civil proceedings as we had in the criminal trial. The criminal trial had produced evidence that O.J. Simpson wore a size 12 shoe and that he routinely shopped at Bloomingdales of New York, one of the 40 stores carrying the Bruno Magli shoes. However, a stronger association between the Bruno Magli shoes and O.J. Simpson was absent. But in a civil trial, unlike a criminal trial, O.J. Simpson, as are all witnesses, was required to give a sworn deposition. During this deposition, O.J. Simpson was asked whether he ever owned a pair of Bruno Magli shoes, either like the Lorenzo or Lyon styles. He responded that he had never owned such a pair of shoes, and added that he would never wear a pair of shoes as ugly as those. I knew this was untrue, because I had already received photographs of Simpson at football games wearing shoes very similar to the Bruno Magli shoes. Across the country, in Buffalo, New York, Rob McElroy, a professional photographer, was in the process of comparing a photograph of O.J. Simpson taken at a profession football game. McElroy knew another photographer, by the name of Harry Scull, Jr., who had taken pre-game warm-up photographs in Buffalo, New York, at a Buffalo Bills vs. Miami Dolphins football game on September 26, 1993. The game marked the 20th anniversary of the year that O.J. Simpson rushed for 2,003 yards when he played football for the Buffalo Bills. McElroy was convinced that one of these photographs showed Simpson wearing the Bruno Magli shoes. The photograph first became publicly known when it was published in the April 23, 1996, edition of the National Enquirer. I had been working with Daniel Petrocelli and Ed Medvene, attorneys representing the Goldman family in the civil trial, in preparation for re-stating the same testimony I had given in the criminal trial. They now requested me to examine the Skull photograph. I explained that it would be necessary to work with the original negative, in order to obtain the maximum amount of detail. Arrangements were made for Scull to travel to the FBI Laboratory with the negative, so that detailed enlargements and enhancements could be made directly from it.

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f i g u r e 1 5 .1 3 Photograph of O. J. S im p son w a lk in g across th e end z o n e prior to th e BuffaJo B ills vs. M iam i D o lp h in s gam e on S ep tem b er 26, 1993, and w earing th e Bruno M agli Lorenzo sh o es. T h e photograph w as tak en by Harry S cu ll, |r. © 1993 Harry S cu ll, fr. All rights reserved.

Scull had used an F-1 Canon manual 35mm camera and 400 ISO Fuji color film. He was trying a new 500mm telephoto lens. To stabilize the large lens, he used a monopod which held the camera at about 5 feet off the ground. During his warm-up shots, Scull had taken three frames of Simpson. Two of those frames depicted Simpson with other persons, and did not include his shoes. But one of those frames, frame #1, showed Simp­ sons entire body, including his shoes, as he walked across the end-zone (Figure 15.13). The photograph was taken in full sun, at approximately 12:45 p m , at a distance of approx­ imately 25 to 30 yards. The Special Photographic Unit of the FBI Laboratory printed frame #1 at different sizes. A normal printing of any negative will average the exposure for the entire print. Likewise, a normal printing of this frame, as depicted in Figure 15.13, averaged the entire content of the photograph. Printing the negative in this manner left the shoes on Simpson rather dark. This made it difficult to see any detail in the shoes. Additional prints were

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F ig u r e 1 5 .1 4 An enlarged area, ta k en from th e sa m e photograph of O.J. S im p son , but printed lighter to sh o w increased d etail of th e black Bruno M agli L orenzo sh o es. © 1993 Harry S cu ll, Jr. A ll rights reserved.

made, this time printing the frame much lighter, and printing only the portion of the picture from the knees down. The result was slightly better and is depicted in Figure 15.14. For a 35-mm negative, printed at such an enlarged size, the photograph contained excep­ tional detail, and many features of the shoes became apparent. Simpson’s right shoe had been captured by the camera in-between steps, and was raised slightly off the surface. This provided a partial view of the bottom of the shoe. To attempt to obtain further detail of the bottom of the right shoe, a final attempt was made to obtain a print of the shoe alone. The original negative was scanned into a computer, and Adobe Photoshop™ software was used to maximize its content. In the photograph, the right shoe of O.J. Simpson was positioned over a portion of the end-zone which had been painted red. Using the Adobe Photoshop™ software, the best results were obtained utilizing only the red channel to maximize the red light that was reflecting off the bottom of the right sole. A computer print was generated. The result provided even more detail of that portion of the shoe than did the photographic prints, and now showed the individual design elements and other details of the bottom of the sole (Figure 15.15). The right shoe of O.J. Simpson was positioned in a toe up attitude, taken just as his heel was striking the ground. To make the best comparison of the features in the photo­ graph, and to be able to demonstrate them in court, 1 used the size 12 Bruno Magli Lorenzo right shoe, obtained from Peter Grueterich, and photographed it in a position that was similar to that in the Scull photograph. This photograph is depicted in Figure 15.16. A comparison showed identical features in both the shoes Simpson was wearing in the

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Figure 15.15 A co m p u ter print m ade u sin g th e original n eg a tiv e of th e O.J. S im p son

photograph. It d ep icts a h ig h ly enlarged part of th e right sh o e on S im p son . © 1993 Harry S cu ll, Jr. A ll rights reserved.

Figure 15.16 A Bruno

M agli siz e 12 Lorenzo sh o e is m o d eled in th e sa m e ap p roxim ate p o sitio n for com p arison w ith th e O.J. S im p son photograph.

photograph, and in the size 12 Lorenzo shoes. These features of the sole included the profile of the sides of the soles, including all of the high and low contours, the clipped off corner of the heel, and even three rows of design elements and the inner border on the bottom of the sole. The features on the uppers included the division seams between the upper components, the round laces and eyelet features, and the bootie upper of the Lorenzo style evident in the left shoe. Any one of the numerous features might be closely matched

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on another shoe design, but not the combination of this many features, particularly since the sole and the upper style had been specifically designed for this particular Bruno Magli shoe only. According to Mr. Lumi, the SILGA company, and 4C, no other shoes were ever produced using the Bruno Magli uppers of this design. Other shoes manufactured with the U2887 Silga soles and bearing the LORD name had never been exported to the U.S., and also had different uppers. There was no doubt that the shoe in the photograph on O.J. Simpson s foot was a black Bruno Magli Lorenzo. The computerized sale sheets showed that out of the 299 size 12 Bruno Magli shoes sold in the U.S., only 29 black Lorenzos had been sold. Two of these were sold to Bloomingdale s of New York, where Simpson frequently shopped. 1 testified in the civil trial on November 20, 1996, to these findings, as well as the original conclusions 1 had reached and provided in the criminal trial. The cross-examina­ tion, as 1 had expected, was routine, and did not contest my conclusion that the shoes on O.J. Simpson in the photograph were Bruno Maglis. Instead, the defense claimed that the Scull photograph of Simpson had been doctored and was not authentic. They hired an individual name Robert Groden, a self-taught photo critic with minimal photographic training and qualifications. He concluded and testified that the photograph contained several characteristics that caused him to believe the photographs were not authentic, but instead had been counterfeited. Earlier, the plaintiff s attorney had asked me to authenticate the photographs. 1 had explained to them that 1 could authenticate the shoes in the photographs, but not the photographs themselves. This was not my area of expertise. 1 referred them to Gerald B. Richards, a retired FBI examiner and former Unit Chief of the Special Photographic Unit of the FBI Laboratory, who had spent a career examining photographic evidence. Richards examined the negatives and the conclusions of Groden and was preparing to testify. But before he was able to testify, the trial recessed for the Christmas break. Over the break, 30 more photographs of O.J. Simpson wearing the black Lorenzo Bruno Magli shoes were located. These photographs had been taken by a pho­ tographer named E. J. Flammer. They had been taken at the same football game on September 26, 1993. They consisted of both individual and group photographs taken with Simpson prior to the game. One of the Flammer pictures was actually published in the November 1993 (volume 3, #20, pi 9) edition of the Buffalo Bills Report, a black-and-white news print paper. 1 also examined the Flammer photographs and concluded and later testified that the photographs depicted a pair of black Bruno Magli Lorenzo shoes being worn by O.J. Simpson. The defense, now desperate for any questions that might raise a doubt, tried in court to make enlargements of the Bundy walkway, and fired several meaningless questions at me regarding them. Now with a total of 31 photographs depicting O.J. Simpson in the Bruno Magli shoes, including one that had been published over 6 months prior to the homicide, the pictures were instantly authenticated. Richards testified concerning the authenticity of the negatives, and to the misleading conclusions about the Scull photograph that Groden had inferred were counterfeit. Groden s testimony was discredited and the absolute proof that O.J. Simpson once owned and wore a pair of black Bruno Magli Lorenzo shoes was now known by all. The jury returned a verdict for the plaintiff, finding O.J. Simpson responsible for the wrongful deaths of Ronald Goldman and Nicole Brown Simpson.

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This case, like any of the thousands of homicides that occur each year, is a sad reminder of the types of individuals who commit these crimes. Before these individuals are convicted, our system of justice requires proof beyond any reasonable doubt. Footwear impression evidence has long been used to contribute toward the facts needed to satisfy that burden of proof. This case is no different in that respect. Although the clothing and shoes were never located, the rare and expensive size 12 shoes, later proven to be owned and worn by O.J. Simpson, were a significant contribution to this case. From a forensic science point of view, one positive aspect of this case was the news coverage of the bloody shoe prints. Because the suspect was O. J. Simpson, one of the more well-known athletes of our time, the coverage was extensive and included repetitive video footage of the shoe prints on the walkway combined with the commentary on their importance. The particular walkway scene with the bloody shoe prints continued to be shown on television around the world, over and over again, as the news of each day on this case was reported. I knew that the importance of the footwear evidence in this case would reach more investigators, attorneys, and law enforcement personnel than any article or class could ever hope to reach. The likelihood that more attention and importance would be given to footwear impression evidence in future cases is now certain.

References

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“Preserving prints o f shoes and tires on hard surfaces”, FBI L a w E n fo r c e m e n t B u l l , 3 0 (6 ), 7-10, June 1961 (revised April 1974). P ro fe ssio n a l S h o e F ittin g , N ational Shoe Retailers A ssociation, N ew York, 1984.

Putnam , BA, “Powder, prints and the effects o f wear”, presented at the International S ym p osiu m on the Forensic A spects o f Footwear and Tire Im pression Evidence, EBI Academy, Q uantico, VA, June 27-July 1, 1994. Qam ra, S. R. and Sharma, B.R. “Naked fo o l marks - A prelim inary study o f identification factors”. F o ren sic S c i I n t i , 16, 145-152, 1980. “T he reproduction o f original evid en ce in the third d im en sio n ”, FBI L a w E n fo r c e m e n t B u l l , 5 (1 2 ), 3-9, 1936. “The reproduction o f sh oep rin t and tiretread im p ression s”, FBI L a w E n fo r c e m e n t B u l l , 16(6), 5-11, 1947. Reynard, J. N., “Footprints - the practical side o f the subject”. P o lic e /., 30 -3 4 , January-M arch, 1948. Roberts, A .D ., “T heories o f dry rubber friction”. T r ib o lo g y I n t i , April 1976. Robbins, L. M., F o o tp r in ts , Springfield, IL: Charles C. T h om as, 1985. Robbins, L. M., “T he individuality o f hum an footp rin ts”, /. F o re n sic S c i , 1978, R odow icz, L., “Polish m e th o d o lo g y o f forensic sh oep rin t id en tifica tio n ”. In fo. B u l l f o r S h o e p r i n t / T o o l m a r k E x a m in e r s , 4 (1 ), M arch, 1998. Rossi, W. A., “T he high incidence o f m ism ated feet in the p o p u la tio n ”. F oot & A n k le , Am erican O rthopaedic Foot and Ankle Society, Inc., 4, 2, 1983. Rossi, W. A., “H ow sh oe sizes grew ”. F o o tw e a r N e w s M a g a z in e , 34 -3 5 , M arch, 1988. R um m elhoff, James Von, “ D oes the print b elon g to the perpetrator?” A ssoc. F ire a rm s a n d T o o lm a r k s E x a m in e r s /., (1 5 )2 , 1983. Russell, J. R., M atharu, S. S., and Brennan, J. S., “A new, portable device for the electrostatic lifting o f m arks”, M P F S L R e p o r t N o . 5 5 , M etropolitan Police, L ondon, June, 1985. Saferstein, R., C r im in a lis tic s : A n i n t r o d u c t io n to F o re n sic S c ien ce , 6th ed., E nglew ood Cliffs, NJ: Prentice-H all, 1997. Salm ons, R., “Identification by flexion creases”, R .C .M .P . G a z e tte , 48( 11), 1986. Sam en, C. C., “Major crim e scene investigation: casting (sh o e and tire im p ressio n s)”. L a w a n d O r d e r M a g a z in e : 5 2 - 5 7 , March, 1972. Schallam ach, A., F ric tio n a n d A b r a s io n o f R u b b e r, Vol. 1, T he British Rubber Producers’ Research A ssociation, 1957-1958. Schallam ach, A., “Abrasion, fatigue and sm earing o f rubber” /. P o ly m e r S c i , 12, 281, 1968. Schallam ach, A., “Abrasion o f rubber by a n eed le” /. P o ly m e r S c i , 9 (5 ), 385, 1952. Schallam ach, A., “H ow d oes rubber slide?”. W ear, 17, 301, 1971. Schallam ach, A., “A theory o f dynam ic rubber friction”. W ear, 6 , 375, 1963. Schallam ach, A., “The adhesion and friction o f sm o o th rubber surfaces”. W ear, 33, 45, 1975.

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Segura,M .A., “F ootprints and tire m arks”, F o ren sic S c i D ig . (U.S. Air Force), 7 (1), 1-17, 1981. S e le c tio n a n d A p p lic a tio n G u id e to P o lice P h o to g r a p h ic E q u ip m e n t, U. S. D epartm ent o f C om m erce,

N ational Bureau o f Standards, NBS Publication 4 8 0 -2 3 , W ashington, D.C., 1980. Serpa, J. F., “Identification o f am id o black enhanced footw ear im pressions in b lo o d ”, presented at the International Sym posium on the Forensic A spects o f Footwear and Tire Im pression Evi­ dence, FBI Academy, Q uantico, VA, ]une 27-July 1, 1994. Sharein, R., “Rainy day id en t”, R C M P G a z e tte , 5 5 (7 & 8), 15-7, 1993. Sharma, B. R., “Foot and footw ear evid en ce”, /. I n d ia n A c a d . F o ren sic S c i , 9 (1 ), 9-13, 1970. Sharma, B. R., F o o tp rin ts, T racks a n d T ra ils in C r i m in a l I n v e s tig a tio n a n d T rials, Central Law Agency, Allhabad 2, India, 1980, 61-77. “Shoe and tire im pressions”, FBI L a w E n fo r c e m e n t B u ll., 2 4 (1 ), 15-17, 1955. “Shoe and tire im pressions put the suspect at the scene o f the crim e”. F o ren sic B u ll. (C om m on w ealth o f Virginia Bureau o f Forensic Science), 4 (4 ), 2-4, 1975. “Shoe buyers guide - footn otes - an A to Z guide to sh oe term in o lo g y ”. R u n n e r s W o rld , 2 5 (1 0 ), October, 1990. “Shoe size conversion research results and recom m en d ation s”. Footwear Industry Team, U.S. D epart­ m ent o f C om m erce, C ontract No. 41 USC 252C (3), July 31, 1979. “Shoeprint on rug links m an to house robbery”, FBI L a w E n fo r c e m e n t B u l l , 18-19, June, 1961. Shor, Y., V inokurov, A., and G lattstein, B., “The use o f an adhesive lifter and pH indicator for the removal and enhancem ent o f shoeprints in d u st”, /. F o ren sic S c i 4 3 (1 ), 182-184, 1998. Slater, J., T e c h n iq u e s f o r th e E n h a n c e m e n t o f 2 - d i m e n s io n a l F o o tw e a r Im p r e s s io n s in B lo o d , diplom a thesis, Canberra Institute o f T echnology, Canberra, Australia, Decem ber, 1993. Soderm ann, H. and O 'C onnell, J. J., M o d e r n C r i m in a l I n v e s tig a tio n , 5th ed.. N ew York: Funk & W agnalls, 1945, 156-168. Som eha, S., “C hem ical techniques for the enhancem ent o f footwear and tire im pressions in Japan”, presented at the International Sym posium on the Forensic A spects o f Footwear and Tire Im pression Evidence, FBI Academy, Q uantico, VA, June 27-)uly 1, 1994. “T he soul o f a run n in g sh o e”. S c ie n c e '82, 3 (6 ), 104-105, 1982. Soule, R. L., “R eproduction o f foot and tire tracks by plaster o f Paris casting”. I d e n tif ic a tio n N e w s, 8-12, January, 1961. Sm erecki, C. J. and Lovejoy, C. O., “Identification via pedal m o r p h o lo g y ”. I n t i C r i m in a l P o lic e R ev., 186-190, August, 1985. Speller, H. C., “The identification o f crepe-rubber sole im pressions”. P olice /., 22, 2 6 9-274, 1949. Spilker, J. G., “Lum inol reaction”. Presentation at the FBI Technical C onference on Shoeprint and Tire Tread E xam inations, FBI Academy, Q uantico, VA, April 1983. Sport Research Review: Adult Foot Structure, Nike, Beaverton, OR, A ugust/N ovem ber, 1990. Stone, R. S., “M athem atical probabilities in footw ear com p arison s”, presented at the FBI Technical C onference on Footwear and Tire Im pression Evidence, Q uantico, VA, April 1984. Subotnick, S. 1., “The biom ech an ics o f running: Im plications for the prevention o f foot injuries”. S p o r ts M e d ., 2 , 144, 1985.

Tart, M.S., D ow ney, A.J., G oodyear, J.G., and A dam s, J.,“The appearance and duration o f feathering as a feature o f wear”. F o ren sic S c i Soc. R e p o r t N o. R R 7 8 6 , August 1996. Tart, M.S., Adams, J., D ow ney, A. J., Goodyear, J. G., and O hene, A., “Feathering, transient wear features and wear pattern analysis: A study o f the progressive wear o f training sh oe o u tsoles”. Info. B u l l f o r S h o e p r in t/T o o lm a r k E x a m in e r s , 4( 1), 51 -68, 1998.

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Walsh, K. A. J. and B uckleton, J. S., “An aid for the detection and correction o f inaccuracies in photographic reproduction o f sh oep rin ts” A F T E /., 19(3), 1987. Walter, E. and W ilson, D .,“lo in t forces research and resource unit physical d evelop er”. I d e n tif ic a tio n C a n ., 8 (2 ), 13-16, 1985. Warren, D. R, Briner, R. C., and Longwell, C. R., “V isualization o f latent sh oep rin t im pressions by the freeze-thaw technique or freeze-thaw HI”, C r im e L a b o r a to r y D ig ., A ugust 1983. Warren, D. R, Lem onds, A. T., Longwell, C. R., and Briner, R. C., “Photography o f footw ear latents using ultra-high contrast tech n iq u es”, A F T E /., 16(3), 113-118, 1984. Warren, G., “Snow print-w ax casting material in form ation ”, A F T E /., 15(2), 77-78, 1983. W a tso n ,}., “A m ethod o f lifting and ph otograp h in g for evid en ce”, /. C r i m in a l L aw , C r im in o lo g y a n d P o lice S ci., 49, 89-90.

W atson, J., “The technique o f lifting and photographing sh oe prints left in d u st”. F in g e r p r in t a n d I d e n tif ic a tio n M a g a z in e , 1-6, May, 1958. Weiser, W., “Analysis o f sh oe prints”, K r im in a lis tik , 4 9 4 -4 9 9 , N ovem ber 1979 (translation from G erm an). W hitlock, 1. K. and Santam aria, R., “Cracks in the sidewall o f a N ike”, presented at the International Sym posium on the Forensic A spects o f Footwear and Tire Im pression Evidence, FBI Academy, Q uantico, VA, lu n e 27-July 1, 1994. W hittle, M. W., G a it A n a ly s is , 2nd ed., O xford, England: B u tterw orth -H einem ann, 1996. West, M. H., Frair, J. A., and Seal, M. D., "Ultraviolet photography o f w ou n d s on hum an skin", /. F o ren sic I d e n tific a tio n , 3 9 (2 ), 8 7-96, 1989. W olfe, J. R. and Beheim , C. W., “D ental ston e casting o f snow im pressions”, presented at the International Sym posium on the Forensic Aspects o f Footwear and Tire Im pression Evidence, FBI Academy, Q uantico, VA, June 27-July 1, 1994. Wojcik, R. J. and Sahs, P. T , “ R eproducing footw ear evid en ce im p ression s”. I d e n tif ic a tio n N e w s, 3 4 (7 ), 6-7, 1984. K iang-Q ing, S., “E stim ation o f stature from intact long b on es o f C hinese m ales”. C a n . Soc. J. F o ren sic S ci., 2 2 , 2 , 1989. Yamazaki, M, “Footwear print reference system using an optical d isc”, presented at the International Sym posium on the Forensic Aspects o f Footwear and Tire Im pression Evidence, FBI Academy, Q uantico, VA, June 27-July 1, 1994. Yeomans, R. E .,“A n on -classic perspective on footw ear id en tification ”, R C M P G a z e tte , 4 7 (6 ), 10-15, 1985. Young, P. A., “Electrostatic detection o f footp rin ts”. P o lice R es. B u ll., 21, 11-15, 1973. Ytti, A. L, “E nhancem ent o f shoeprints w ith Polilight - A case report”, presented at the International Sym posium on the Forensic A spects o f Footwear and Tire Im pression Evidence, FBI Academy, Q uantico, VA, June 27-JuJy 1, 1994. Zeldes, 1., “Footwear and tire track exam ination in the Soviet U n ion ”, /. F o ren sic I d e n tif ic a tio n , 3 9 (6 ), 1989. Zercie, K. B, “The role o f footw ear evidence in the reconstruction o f a crim e scen e”, presented at the International S ym posium on the Forensic A spects o f Footwear and Tire Im pression Evi­ dence, FBI Academy, Q uantico, VA, June 27-JuJy 1, 1994. Zm uda, C. W., “Identification o f crepe sole sh o es”, /. C r im in o L , C r i m in a l L a w a n d P o lice S ci., 4 4 (3 ), 374-378, 1953. Zweidinger, R. A., Lytle, L. T., and Pitt, C. G., “Photography o f b lood stain s visualized by lu m in o l”, /. F o ren sic S c i , 18(4), 2 9 6 -302, 1973.

Glossary

Adhesive lifter Any of a variety of adhesive coated materials or tapes used to lift finger­ prints or footwear impressions. They are primarily used to lift powdered impressions from non-porous surfaces. Air sole An outsole or midsole having an air pocket or cushion incorporated into it. Ambient light The available or existing light that surrounds the object being photo­ graphed, i.e., natural light. Anatomic Relating to the shape of the body or parts of the body. As it relates to the foot, the natural shape of the foot. Ankle The joint formed at the lower ends of the two leg bones, where the fibula and tibia meet the talus bone of the foot. Anterior The forward portion. Arch Portions of the foot that are curved in an arc formation. The main arch is the longitudinal inner arch that runs along the inner border of the foot. Arch area The area of the sole of the shoe immediately below the longitudinal arch of the foot. Arch support A device made of leather or synthetic material that can be shaped to a person's longitudinal arch and inserted or built into a shoe to give support to that person's natural arch. Attenuated light Supplemental light that is added when photographing the luminol reaction. The light is sufficient to allow for recording of the object on photographic film, but not to significantly interfere or wash out the luminescence. Athletic shoes Any of a number of shoes used for a variety of athletic or casual athletic wear, most commonly including running, walking, basketball, tennis, and other sport footwear. Autoclave An oven or heated pressure chamber used to vulcanize rubber. Back strap A strap of leather or material running down the center and rearmost portion of the heel upper of some shoes. Ball The part of the foot just behind the large toe, formed by the intersection of the first metatarsal phalangeal joint. Bare footprint An impression made by a naked foot. Biomechanics The science that concerns itself with the structure and mechanical move­ ments of parts of the body, such as the foot.

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Blocker An oversized unit sole made of one or more components that are later die cut and/or trimmed to size. Brannock device Registered name of a foot-measuring device of the Brannock Device Company. CAD-CAM Abbreviation for Computer Assisted Design-Computer Assisted Manufac­ ture. Calendering A process where raw unvulcanized rubber is passed between rollers under heat and pressure to produce textured or designed outsole material. Casting The filling of a three-dimensional footwear impression with material that takes on and retains the characteristics that were left in that impression by the footwear. Also, a method of making a mold by first making a three-dimensional model of a shoe and then making a cast from that model. Casual shoe A shoe designed for easy, informal wear, normally having a leather upper and either a leather or a soft synthetic sole. Chemical etching A form of texturing a mold, utilizing an acid bath that erodes selective portions of the metal, leaving a resulting texture or pattern. Class characteristic An intentional or unavoidable characteristic that repeats during the manufacturing process and is shared by one or more other shoes. Clicker A name commonly used to describe a machine that strikes a steel die that cuts through outsole and/or midsole materials in a cookie cutter fashion. Combined class characteristic The combined occurence of two or more independent class characteristics. Compression molded A molding method in which a molding compound is placed into an open mold cavity, after which the mold is closed as heat and pressure are applied, causing the molding compound to melt and conform to the size and shape character­ istics of the mold cavity. D enotes that a particular characteristic or set o f features coin cid es and con form s w ith the respective characteristic or set o f features.

C orrespon ds

Court shoe An athletic shoe used for tennis, basketball, and other court sports. Crepe rubber A natural, unvulcanized rubber used for soles and heels. Most crepe rubber made today is synthetic crepe rubber. Cut outsole An outsole whose final shape and/or size has been affected by cutting or trimming. Deformable impression An impression that causes the surface to deform, either perma­ nently or temporarily. Permanent deformable impressions would include those impres­ sions in sand, soil, and snow, whereas a temporarily deformed impression would include those on skin, carpeting, etc. Also referred to as a depressed mark. Degree of wear The extent to which a particular portion of the shoe is worn. Dental stone A gypsum product similar to plaster of Paris, but with different properties due to the way it is manufactured. It is far superior to plaster of Paris for use in casting footwear impressions because of its hardness and durability. Die cutting Cutting outsoles or other shoe components by forcing a sharpened steel die through preformed outsole material with the assistance of a "clicker" machine. Die stone A gypsum product included among the dental stones, having a very high compressive strength.

Glossary

477

Dies Steel dies having a sharp edge used to cut shoe parts and outsoles. Differences Denotes a characteristic or feature that is so strong and reliable that it, in itself, indicates non-identity. Usually a difference will be a different class characteristic, such as the specific design or specific physical size of the design. Normal variations in the impression process, the absence of cuts evident in a questioned impression that appear on the shoe, or the normal advancement of wear with time do not constitute a comparative difference. Direct attach A process wherein the lasted upper of a shoe is lowered into the mold cavity after which the mold closes tightly around the shoe upper, after which the midsole or outsole is molded directly onto that upper. Distortion An unclear or inaccurate representation of the shoe outsole in the impression due to interference with the impression making process or the impression’s subsequent recovery. Dorsi-flexion Raising the anterior portion of the foot. Dress shoe A shoe for more formal or dressy wear. Dry origin A footwear impression that contained no significant moisture at the time it was made, either from the footwear itself or from the surface. Dual density A term used for a midsole-outsole combination, where the outsole and midsole are composed of materials having different densities. EDM Electrical Discharge Machine. A machine used to produce molds by electrically burning away the undesired metal portions. Electrostatic lifting device A device consisting of a high-voltage supply used with a special conductive lifting film to electrostatically transfer a dry origin footwear impression from a surface to the film. Electrostatic detection apparatus A device primarily used to detect indented writing on documents, which can also be used to detect footwear impressions on paper items. Enhancement Rendering an impression more clear or more visible through physical, photographic, or chemical means. Ethylene vinyl acetate (EVA) A soling compound often produced in an expanded form. Eversion Raising of the outer border of the foot. Expanded materials Soling materials that have a lower specific gravity and which expand during the molding process. Extension Movement of the foot forward and downward. Examination quality photographs Sometimes called evidence photographs, they are closeup photographs taken of specific items, such as footwear impressions, in a manner to capture the maximum detail so that they can later be used in a scientific comparison. Fixatives A spray or powder applied cautiously to a footwear impression prior to casting, to prevent it from loss of detail when the casting materials is applied to it. Flat foot A foot with a dropped or unsupportive longitudinal arch. Foot pad The main portion of the bottom of the foot, absent the toes and toe stems. Foot stance Position of the feet while standing or walking. The feet may be turned inward or outward. Footwear Any apparel which is worn on the foot, such as shoes, boots, etc. Footwear Industries of American (FIA) The trade association of the U.S. footwear man­ ufacturers.

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Foxing A component of the shoe used to reinforce and/or cover the edge of the shoe where the outsole and the upper join together. Usually a strip of rubber (foxing strip) wrapped around the lower part of the shoe. F u ll f r a m e p r i n t

A ph otograp h ic enlargem ent which includes printing the entire surface o f the

negative.

Gelatin lifter Gelatin and other materials laid on a pliable backing that can be applied to a porous or non-porous surface to lift a footwear impression. The lifter can be white, black, or transparent. General condition The overall condition or general amount of wear (i.e., unworn, severely worn, slightly worn). General crime scene photography General photographs taken at a crime scene to show a view of evidentiary objects and their surroundings. Hallux The large toe of the foot. Hand milling In the mold making operation, the process of guiding by hand the milling of metal during the manufacture of a mold, as opposed to the milling operation being directed by a computer. Heel A separate component attached to the rear portion of the outsole. In a one piece outsole, it is the a raised area in the rear portion of the outsole. In a flat shoe, it is the heel area. Heel area The area that is, or would normally be, occupied by a separate heel component. Heel backstrap A piece of material centered at the rearmost portion of some shoes and extending from the heel collar down to the upper portion of the midsole. Heel collar (or Ankle collar) The highest portion of the shoe upper in the rear of the shoe that surrounds the ankle when the shoe is worn. Heel counter A reinforcement or stiffener placed between the outside and the lining at the back of the shoe to prevent the upper from collapsing. Heel stabilizer A synthetic or molded piece placed between the sole and the heel to act as a motion control device and to add stability to that area. Identification The positive association of an impression as having been made by a single shoe, to the exclusion of all others. Identifying characteristic A particular characteristic, individual to a specific shoe, that resulted from an occurrence that randomly added or removed something from the shoe outsole and which caused or contributed to making that shoe outsole unique. Impression evidence Objects or materials that have retained certain characteristics or other objects or materials that have been impressed against them. indentation materializer A device capable of both electrostatically lifting dry residue impressions as well as indented handwriting and footwear impressions. Injection molding A molding process in which the sole or entire shoe is formed by injecting the midsole or outsole materia] into a closed mold. Variations of the process include molding outsoles separately (unit soles), and molding outsoles directly onto lasted shoe uppers (direct attach soles). Inlay The inner layer of the shoe upon which the foot rests. Sometimes synonymous with insole.

Glossary

479

Insole A piece of material that is shaped and sized to fit inside the shoe where the foot rests. An inlay. Inversion Raising the inner border of the foot. Known shoes Shoes that have been seized from a known individual, which are compared with the footwear impressions from the crime scene for the purpose of elimination or identification. Last

A piece of wood, metal, or synthetic material that has been shaped and sized to simulate a foot. The last serves as a form over which the shoe is built. Lasted A shoe upper on a last awaiting the bottom to be cemented or molded onto it. Lateral On the outer side. Lift To transfer an impression from its original surface for the purpose of recovering it from the crime scene and for providing better contrast. Logo A name, design, or pattern that appears on the sides and bottoms of outsoles of athletic shoes and which is a trademark of the manufacturer. Logo area The area of the shoe, normally beneath the center of the outsole, where a logo such as a company name or trademark are included in the sole design. In some cases, this area may be defined in a shoe sole in the form of a rectangle or oval, yet not contain a logo name. Manufacturer's shoe size The shoe size that a particular manufacturer has assigned to a particular shoe, and which is indicated on the shoe and/or shoe box. Matches Used by some in lieu of the word corresponds. Not a good comparative term. To say a shoe print “matches” a shoe may be misunderstood as an identification. Mark A two-dimensional impression. A shoe print. Medial On the inner side, the side of the mid-line of the body. Metatarsal bones The long bones of the foot, which join with the phalanges (toes). Microcellular Made of expanded soling material with small closed cells and a density of less than 1. A density of .95 would be more dense than a density of .75. Midsole A component found on some shoes that is often different in color, density, or materials, and is located between the outsole and the shoe upper. Molded outsole An outsole which is formed in a mold and whose final size and shape take on the characteristics of a mold. Multi-density or multi-component midsole A midsole which is composed of two or more materials, often of different colors and/or densities. Non-identification

An elimination of any possibility that a shoe made an impression.

Oblique light Light that is positioned at a low angle of incidence relative to the surface being photographed. Also referred to as side-lighting. Open pour molding A method of making outsoles normally utilizing polyurethane (PU). The mold is filled by pouring the PU into the mold cavity and then closing the mold. Single unit soles and direct attach soles can be made utilizing this process. Outsole The outermost sole of a shoe. The portion of the shoe that contacts the ground and is exposed to wear.

480

Footwear Impression Evidence, 2nd Edition

Plaster A very general term, including all gypsum casting materials. Also used to define the softer gypsum materials having a lower compressive strength. Plaster of Paris A gypsum casting material produced by heating crushed gypsum in an open oven at high temperatures. Although used for years as a casting material for footwear impressions, it is no longer regarded as an acceptable material, due primarily to its softness. Polyurethane (PU) A family of resins produced when di-isocyanate reacts with organic compounds containing two or more active hydrogens. It is used in both the outsole and midsoles of shoes. PVC polyvinyl chloride A thermoplastic polymer used in shoe outsoles. Plantar Pertaining to the sole of the foot. Plantar flexion Lowering the anterior portion of the foot. Porous A material or surface which is open grained, and which liquids or small solids could penetrate. Posterior The rear portion. Random characteristics Characteristics in which the size and/or shape and/or position and/or orientation depend, to some degree, on chance. Reference shoes Shoes known to belong to an individual, which are used as a known comparison standard in a barefoot comparison. Release agent A spray or powder applied cautiously to a three-dimensional footwear impression to prevent soil from clinging to a cast of that impression. Reverse photograph One in which the negative is turned onto the reverse side to make a print. Ritz stick A foot measuring device used for heel-to-toe and ball width measurements. Rubber A material made from the extract of the rubber plant or synthetic versions of the same material. Running shoe A shoe specifically designed for jogging or running. Same Infers it is identical. Sequenced enhancement A series of two or more enhancement procedures arranged so that none adversely affect the success of the next. Shank Part of the sole of the shoe between the heel and the ball. Also a piece of steel or leather or synthetic material placed between the insole and the sole from the heel forward, to support that area of the shoe. Shoe print A two-dimensional impression of a shoe. A shoe mark. Shoe upper The components of the shoe excluding the outsole and/or midsole. Similar A more general term which denotes a likeness or resemblance of a feature, such as the design, but does not infer that they are specifically the same. Siping The process of creating a pattern of parallel cuts across a rubber sole. Commonly found on deck or boat shoes. Sneaker Historically, the original athletic shoe, having a fabric upper and gum rubber sole, and also having the characteristic foxing strip around the upper-outsole joint. In more modern times, a general reference to an athletic shoe of any type. Snow Print Wax Registered name of an aerosol product used to assist in the photography and casting of footwear impressions in snow.

Glossary

481

Sock clad A foot covered with a sock. Sole or outsole The extreme bottom portion of the shoe. The part of the shoe that contacts the ground. Sprue The piece of material formed in the feed channel through which the material is injected in some injection molding processes, and that remains attached to the shoe when the molding operation is finished. Sprue mark A mark left after removal of the sprue. Stippling A texture or pattern which is mechanically struck into the surface of a mold by individually striking a steel die with a hammer. It is commonly found on surfaces of a midsole or outsole mold. The hand-struck stipple pattern is unique to a particular mold. Stitching Characteristic marks left by a tool used when joining the various unvulcanized rubber parts of a shoe together prior to vulcanizing. It is associated primarily with shoes made utilizing unvulcanized rubber soles, foxing strips, and rubber upper com­ ponents. Also, the application of thread through the bottom (bottom stitched) or side (side stitched) of a shoe to help join the outsole to the upper. Styrene butadiene rubber (SBR) A rubber compound commonly used in the compression molded process. Texture A rough surface of shallow design added to a mold through a stippling or a chemical etching process. Texture patterns vary in their position and features and are unique to a mold. The texture is reproduced in shoes made in that mold. Test impression An impression made utilizing a known shoe for the purposes of using it in a footwear impression examination. Toe bumper guard A thick strip of rubber that is placed around the front perimeter of the shoe surrounding the toe area. Toe cap A piece of rubber or material placed across the top of the toe area or vamp of a shoe to increase the durability and strength of the shoe in that area. Tongue A strip of material covering the instep of the foot lying beneath the shoe laces. Three-dimensional impression An impression with the dimension of length, width, and depth. Thermoplastic rubber (TR) A polymeric material that maintains rubber-like properties. Two-dimensional impression An impression, which for all practical purposes, has the dimensions of length and width but not a significant depth. A mark. Unit sole An individually molded or cut unit of a predetermined size. It must be glued and/or stitched to the upper. Upper All of the components of the shoe above the midsole and outsole. Variations Those variables or subtle dissimilarities that normally exist between repetitive impressions of the same shoe. Vulcanization An irreversible process in which a rubber compound is heated under pressure resulting in a chemical change in its structure. The process to which shoes with raw rubber components are subjected in order to permanently bond the compo­ nents together. Wear The erosion of the outsole due to frictional and abrasive forces that occur between the outsole and the ground.

482

Footwear Impression Evidence, 2nd Edition

Wear characteristics Changes in the surface of the outsole that are observable in the impression and/or known shoe and that reflect the erosion of the surface of the outsole. Wear pattern The position of wear on a shoe. An arrangement or pattern of wear characteristics that stand out against areas of relatively less or greater wear. Wellman outsole cutting machine A machine which is used to cut outsoles from unvul­ canized calendered material. It utilizes a template that dictates the size and shape of the outsole. A sharp knife blade travels rapidly around the template and cuts the sole from the calendered material. Welt A strip of leather or synthetic material between the upper and the sole to which each part is, in turn, attached. Wet origin A footwear impression containing significant moisture at the time it is made, contributed by either the footwear and/or the surface. Although the wet impression will eventually dry, it is still categorized as an impression of wet origin.

Appendix: Source Inform ation

Company

Supplies for footwear evidence

Hans Aebersold Rue de la Cole 81 2000 Neuchâtel TVA 318 947 Switzerland tel: 4 1 79 240 54 36 fax: 41 32 721 15 00

Holder for holding shoes for making known impressions. General footwear and crime scene supplies, rulers, etc.

W.l. Bodziak Forensic Consultant Services tel: 904-287-8860 fax: 904-287-8861

Training, examinations of footwear and tire impression evidence

BVDA International The Netherlands [email protected] tel: 31 (0) 23-5424708 fax: 31 (0) 23-5322358

Gelatin lifters, powders, crime scene supplies

David Jason Associates, Inc. P.O. Box 131 Commack, N.Y. 11725 1-800-352-8280 fax: 516-543-3137

Zetalabor casting material, polyvinylsiloxane

Zhermack Via Bovazecchino, 100 45021 Badia Polesine (Rovigo) Italy www.zhermack.com tel: 39 (0) 425-597611 fax: 39 (0) 425-53596

Zetalabor casting material

483

Footwear Impression Evidence, 2nd Edition

484 Dentsply Inlernational, Inc. 570 West College Avenue RO. Box 872 York, Pennsylvania 17405 WWW. den tsp ly . CO m tel: 800-877-0020 (customer service) tel: 717-845-751 1

Castone (dental stone), buff color, 25 lb carton

DOJE s Inc. RO. Box 500 Ocoee, Florida 34761 tel: 407-880-8149 fax: 407-880-8150

Polyvinylsiloxane, general forensic supplies

Eastman Kodak 342 State Street Rochester, New York www.kodak.com 800-242-2424

Kodak Roller Transport Cleanup Film, 50 sheets 1 1 x 1 6 in., Catolog #1 1 4 1555

Evident Crime Scene Products 739 Brooks Mill Road Union Hall, Virginia 24176 tel: 800-576-7606 tel: 540-576-3512 fax: 888-384-3368

Bio-Foam, fingerprint powders, dental stone, rulers/scales, lifting film. Pathfinder and other electrostatic lifters

Foster & Freeman Ltd. 25 Swan Lane, Evesham, Worcs. WRl 1 4PE, U.K. [email protected] tel: 0386 4 1061 (Evesham) tel: 703-443-9127 (U.S.)

Electrostatic Lifter (DLK), Electrostatic Detection Apparatus (ESDA)

Identicator Corporation 4051 Glencoe Avenue Marina Del Ray, California 90292 www.iden ticato r.co m tel: 310-305-8181 fax: 310-578-1910

Inkless impression supplies

Instruments S.A., Inc. Forensics Group 3880 Paul Avenue Edison, New Jersey 08820 www.crimescope.com tel: 800-438-7739 tel: 732-494-8660 fax:732-549-5125

Crimescope and Mini-Crimescope, Shortwave UV Reflectance Imager

K9 Scene of Crime Equipment, Ltd. 116a Bailiff Street Northampton NNl 3EA, U.K. 44(0) 1604 24651

Pathfinder (hand-held electrostatic lifter)

Appendix: Source Information

485

FCinderprint Company, Inc. RO. Box 16 Martinez, California 94553 kinderp rin [email protected] derp rin 1.co m tel: 800-227-6020 tel: 510-686-6667

Electrostatic lifters, gelatin lifters, handiprint adhesive lifters, fingerprint powders. Snow Print Wax, physical developer kit, general crime scene supplies

Kjel] Carlsson Innovation Rinkebyvagen 18, S-172 37 Sundbyberg, Sweden tel: 46 8 280 784 fax: 46 8 288 074

Vacuum Box (VB), Dustprint Electrostatic Lifter, Microsil, photographic equipment

Lightning Powder Company, Inc. 1230 Hoyt Street, S.E. Salem, Oregon 97302-2121 tel: 800-852-0300 tel: 503-585-9900 fax: 800-588-0399 fax: 503-588-0398

Electrostatic lifters, gelatin and adhesive lifters, fingerprint powders. Snow Print Wax, physical developer. Minutiae newsletter, linear scales, L-shaped ruler, forensic training

Lynn Peavey Company PO. Box 14100 Lenexa, Kansas 66215 tel: 800-255-6499 tel: 913-888-1066

Electrostatic lifters, general crime scene supplies, fingerprint powders

Mistral Security 7910 Woodmont Avenue Suite 1070 Bethesda, Maryland 20814 WWW. mistralgro up.co m tel: 301-913-9368 fax: 301-913-9369

“Blue” (Bromphenol Blue spray)

EREZ Forensic Technology Israel fax: 972-2-651-3118

“Blue”

Morris-Kopec Forensics, Inc. 631 Palm Springs Dr. Suite 107 Altamonte Springs, Florida 32701 tel: 407-831-9921 fax: 407-831-9922

Pre-mixed chemical formulations for enhancement, fingerprint powders

N.V. Yves Weltjens Bosdel 43 3600 Genk Belgium tel: 32-89-35-31 15 fax: 32-89-35-2191

Black adhesive lifters

486

Footwear Impression Evidence, 2nd Edition ODV Incorporated RO. Box 180 So. Paris, Maine 04281 tel: 800-422-3784 fax: 207-743-5000

Gelatin lifters, powders, Polilight, UV lamps, electrostatic lifters, general crime scene supplies

Patterson Dental Supply, Inc. 1031 Mendota Heights Road St. Paul, Minnesota 55120 www.pattersondental.com tel: 612-686-1600 tel: 800-328-5536 fax: 612-686-9331

Dental Stone (Denstone), buff color, 25 lb carton

Payton Scientific, Inc. 244 Delaware Avenue Buffalo, New York 14202 tel: 716-852-6213 fax: 716-852-3268

Luma-lite

Poly Shapes Converters, Inc. P.O. Box 156 140 East End Drive Gilberts, Illinois 60136 tel: 708-428-5311

Plastic foot covers

Universal Tracking Services 7133 Mechlam Road Everson, Washington 98247 tel: 360-966-7707

Tracking instruction and services, video tape on tracking

Index

forensic studies, 385 medical and anthropological studies, 384-385 Netherlands forensic study, 392 Royal Canadian Mounted Police research, 390, 392 Swedish Police College study, 392 U.S. Army study, 383 footwear matching conditions for examination request, 399 examination guidelines, 404-406 inner surface of shoe impressions, scenarios for encounter, 381 origin of impressions, 398 positive versus negative identification, 404, 406 purpose, 399 trying on of shoes by suspect, 400 height estimation, 407 impression examination, 397-398 known standards clay, 397 foam impressions, 394 inked impressions, standing and walking, 393-394 photography, 395 reference shoes, 395 sand, 397 slipper casts, 394-395 two-dimensional versus three-dimensional impressions, 392-393 videography, 395-396 x-rays, 396-397 Zetalabor, 394 podiatrie examination, 400-401 results reporting, 406-407 sock-clad feet, 381 Biofoam, test impressions bare feet, 394 known footwear, 302

Adhesive lift bromphenol blue-stained impressions, 156-157 difficulty, 99-100 enhancement of footwear impressions, 144 indications, 117 lifter features, 119 photography, 121-122 transparent lifters, 119-120 Age, footwear impressions, 3-4 Amido black aqueous-based enhancement, 167-168 blood staining reaction, 165 methanol-based enhancement, 165-166 Ammonium thiocyanate, 145-147 Antimony trichloride, enhancement of footwear impressions, 160 Athletic shoe, history, 197-198 Auto paint primer spray, casting with dental stone, 94-96 Awareness, detection o f footwear impression evidence, 1-2

B Back strap, definition, 475 Barefoot impression case studies of examination, 408-411 class characteristics, 401 details, 404 early considerations by investigator, 399-400 fingerprint comparison, 381 foot individuality biometrics, 385 Canadian Army foot survey, 383 Federal Bureau o f Investigation research, 386-390

487

488 Blocker unit assembly, 253 cutting, 253 definition, 253 homicide case study in impression identification, 257-258, 260-261 Nike Cortez design, 260-261 specific-size components, 261-262 variability, 253, 255-256, 278 Blood impressions, see also Simpson trial chemical enhancement amido black, 165-168 diaminobenzidine, 164-165 Fuschin Acid, 168-169 leuco crystal violet spray, 160, 161-163 leuco malachite green, 173-174 luminol, 169-173 ninhydrin, 169 overview, 160-161 Patent Blue, 168 5-sulfosalicylic acid fixation, 161 Tartazine, 169 lifting, 124, 125 removal from crime scene, 160-161 Bromphenol blue enhancement procedure adhesive lift, 1 5 6 -157 spray method, 156-157 formulation, 155 principle of footwear impression enhancement, 154-155 Bruno Magli shoe, see Simpson trial

Calendered rubber cutting, 244 design rollers, 240-24 1 processing, 240-242 variability sources, 243-244, 266, 277 Camera, see Photography Carpet electrostatic processing, 13 holographic detection o f footwear impressions, 8 lifting o f footwear impressions, 128 luminol enhancement in Simpson case, 441-442 quality of footwear impressions, 10-11 Case studies, see Denver multiple homicide case; Naperville case; New York Gap store homicide case; New York serial robbery/homicide case; St. Croix homicide case; Simpson trial; South Carolina homicide case

Footwear Impression Evidence, 2nd Edition Casting benefits over photography, 61-63, 65 definition, 59-60 dental stone air drying, 82 cleaning, 82-83 gypsum conversion, 69-70 history of use, 67 mixing, 71-72, 78-80 pouring, 80-81 preparation of footwear impression, 73-74 qualities, 67, 68 shipping and storing of casts, 83-84 storage o f dry mix, 70-71 terminology, 68, 70 water-to-powder ratio, 7 0 -7 1 watering out, 72, 79 drying, 81 -82 equipment for crime scene, 72-73 fixatives, 77 forms, 74-76 gypsum casting product comparisons, 68-69 importance, 60, 96-97 moulage, 66 paraffin wax recommendations for casting, 65-66 snow impression casting, 92-93 photography, 83 plaster of Paris, 59, 65, 66, 67, 68, 70 preparation of evidence, 361 re-enforcement materials, 76 release agents, 77-78 setting process, 81 shrinkage and expansion o f casts, 364 silicone, 65, 68 snow impression casting auto paint primer spray with dental stone, 94-96 conditions o f snow, 96 dental stone pouring, 86-87 history, 84-85 melting, 88 paraffin wax, 92-93 snow print wax, 85-86, 87-88 sulfur casting, 88-92 success of definite identification, 24 underwater casting, 82 CCTAS, see Converse Chuck Taylor All-Star shoe Class characteristic bare feet, 401 combined class characteristics examples, 330 mold variations, 331-334 reduction of shoes for positive identification, 332-333

Index significance, 334-335 definition, 329 single class characteristic features, 329-330 Clay, test impressions bare feet, 397 known footwear, 301-302 Clicker, definition, 476 Clothing, lifting of footwear impressions, 129-130 Compression-molded outsole, see Molding process Computers computer-aided design-computer-aided manufacture, shoe molds, 199, 218 enhancement and processing of footwear impression images, 176-178 Converse Chuck Taylor All-Star shoe (CCTAS) assembly variations, 220-222 combined class characteristics, 330 compression-molded outsole variations diagonal lines, 220 diamond designs, 219-220 hand-made versus computer-aided design-co m p uter-ai ded man ufacture molds, 216-219 shoe brand and size area, 220 stippling, 220 transverse bars crossing toe and heal areas, 219 foxing strip variations, 220-221 outsole dimensions and sizing, 185-186 toe bumper guard variations, 221-222 Courts attitude towards footwear impression evidence, 2 case studies, see Denver multiple homicide case; Naperville case; New York Gap store homicide case; New York serial robbery/homicide case; St. Croix homicide case; Simpson trial; South Carolina homicide case expert witness definition, 375 footwear examiner qualifications, 375-376 last minute examinations, 379 pretrial conferences, 377 presentation o f evidence photographs, 378 prints, 378 slides, 378-379 visual aid functions, 377 Court shoe, definition, 476 Crime scene general procedures, 21,25 hypothetical example, 22-24 photography, see Photography reconstruction with footwear impression evidence, 4,414-415,443-445

489 sealing, 21 searching for footwear impression evidence exterior areas, 21 likely surfaces, 18-20 near other impressions, 21 overview, 22 path through crime area, 20-21 point o f crime, 19 point o f entry, 20 point of exit, 21 Cushion, lifting of footwear impressions, 128 Cut process blocker unit assembly, 253 cutting, 253 definition, 253 homicide case study in impression identification, 257-258, 260-261 Nike Cortez design, 260-261 specific-size components, 261-262 variability, 253, 255-256,278 calendered rubber cutting, 244 design rollers, 240-241 processing, 240-242 variability sources, 243-244, 266, 277 die cutting characteristics in impressions, 250, 253 die variance, 250 process, 247 variation between outsoles, 247-249, 253, 277 materials, overview, 237,240 pre-molded oversized unit soles, 245 pre-molded sheets, 244-245, 278 pre-molded specific-size unit soles, 245,247, 278 Wellman outsole cutting machine boots, 266-267 distribution of use, 262 materials for cutting, 262 templates, 263 variations in products, 263-266, 277 Cyanoacrylate fuming footwear impression enhancement, 158-159 principle, 158

D DAB, see Diaminobenzidine Dental stone, see also Casting air drying, 82 cleaning, 82-83 gypsum conversion, 69-70 history of use, 67

490 lifts, 124 mixing, 71-72, 78-80 pouring, 80-81 preparation of footwear impression, 73-74 qualities, 67, 68 shipping and storing o f casts, 83-84 snow impressions, 86-87, 94-96 storage of dry mix, 70-71 terminology, 68, 70 water-to-powder ratio, 70-71 watering out, 72, 79 Denver multiple homicide case background, 418 left versus right shoe impressions, 418-419 manufacturing variability evidence, 418-422 superimposition of impressions, 419-420 DFO,see l,8-Diazafluoren-9-one Diaminobenzidine (DAB) blood staining reaction, 164 enhancement procedures soaking technique, 164 towel or bottle application, 164-165 formulation, 164 l,8-Diazafluoren-9-one (DFO), enhancement of footwear impressions, 152 Die cutting, see Cut process Digital camera, examination quality photography, 33 Dirt, tracking on clean surface, 12-13 Discretion news coverage in Simpson trial, 431,458 obtaining known suspect footwear, 279 Distortion, causes in footwear impressions, 362-364 Dry origin impressions, overview, 8-14 Dual-density shoe, injection-molded outsoles, 224 Dulling spray, negative test impressions of footwear, 297 Durability, footwear impressions, 3 Dust, cleaning from impressions and lifts, 114-115

EDM, see Electrical discharge machine Electrical discharge machine (EDM), shoe mold manufacturing, 200 Electrostatic lift development, 101 dust, cleaning from impressions and lifts, 114-115 enhancement of impressions, 142 film handling and storage, 113-114 positioning, 107-109 probe placement on lifting film, 109

Footwear Impression Evidence, 2nd Edition removal, 109-1 11 rolls, 1 11-1 12 ground device positioning, 105, 107 indentation detection with electrostatic detection apparatus, 127-128, 142-143 instrumentation charging, 104 commercial instruments, 101-102 components, 101, 102 Pathfinder ESL operation, 113 Vacuum Box, 112, 127-128, 142-143 paper footwear impressions, 127-128 photography of black lifting film impressions, 115 potential substrates, 13-14, 103-104 Enhancement, footwear impressions chemical methods, see specific chemicals classification o f techniques, 135 forensic photography alternate light sources, 139-140, 144 cross polarization, 138 filters, 137 high-contrast photography, 136-137 indications, 135-136 infrared light, 138-139 oblique light, 4 4-45,47-50, 52, 137 ultraviolet light, 138, 144 physical methods, see Adhesive lift; Electrostatic lift; Fingerprint powder; Fluorescent powder; Gelatin lift selection of technique, 135, 174-175 three-dimensional impression enhancement, 175-176 computer enhancement, 176-178 Evidence tag, examination quality photography, 40 Expert witness definition, 375 footwear examiner qualifications, 375-376 lastminute examinations, 379 presentation o f evidence, 377-379 pretrial conferences, 377

FBI, see Federal Bureau o f Investigation Federal Bureau o f Investigation (FBI) database of known footwear, 284-285 foot individuality studies, 386-390 request for assistance by non-federal law enforcement, 431 scale for photography, 38 Fingerprint, features, 347 Fingerprint powder

Index footwear impression enhancement, 14-16, 126, 144 lifting of footwear impressions, 126 test impression methods clear adhesive, 294, 296 gelatin lift, 296 oil coating, 296 roller transport film, 293-294 Fixatives, casting, 77 Flash, trimming and impression, 212, 214 Fluorescent powder, footwear impression enhancement, 144 Foot anatomy, 308 arch examination, 403 ball area examination, 402 forefoot wear, 310-312 heel examination, 403 heel wear, 312-313 individuality biometrics, 385 Canadian Army foot survey, 383 Federal Bureau o f Investigation research, 386-390 footwear association studies, 384 footwear industry studies, 383-384 forensic studies, 385 medical and anthropological studies, 384-385 Netherlands forensic study, 392 Royal Canadian Mounted Police research, 390, 392 Swedish Police College study, 392 U.S. Army study, 383 movement in walking cycle, 308-310 toes, 401-402 Foot angle, gait analysis, 5 Foot impression, see Barefoot impression Forefoot, wear, 310-312 Foxing strip definition, 270 variations, 220-221,272 Frequency, footwear impression evidence, 2-3 Fuschin Acid, enhancement o f bloody footwear impressions, 168-169

Gait analysis coefficient of friction and slip resistance o f shoes, 5-6 measurements, 5 reliability, 5 tracking signs, 6-7

491 Gelatin lift enhancement o f footwear impressions, 144 fingerprint powder test impression, 296 indications, 116-117, 118 lifter film, 117-119 photography, 121-122 success o f definite identification, 24 wet origin impressions on dirty surfaces, 16 Glass, footwear impression development from trace materials, 9-10 Golden rules, footwear examination, 374 Grass, lifting of footwear impressions, 128 Gypsum, see casting Gypsum cement, definition, 69

H Heel foot characteristics, 403 shoes choice and positioning in shoe manufacturing, 270 wear, 312-313,325-326 Heel backstrap, definition, 478 Heel collar, definition, 478 Heel counter, definition, 478 Heel stabilizer, definition, 478 Height, see Stature Holography, detection o f footwear impressions on carpet, 8 8-Hydroxyquinoline, 157-158

Identification, see Positive identification Identifying characteristics changes as shoe wear continues, 353-355 clarity, 338-339 number required for identification, 347-352 positive identification, 371-372 random identifying characteristic bare feet, 404 confirmation, 341 definition, 335, 349 value o f one confirmable random characteristic, 342-344, 347, 352 wear, 350 reproducibility and repeatability in test impressions, 339-340 types, overview, 335-338 uniqueness, 344-346

492

Footwear Impression Evidence, 2nd Edition

Impression evidence, see also Courts; Lifting; Photography; Test impressions definition, I preparation, 359 receipt procedures, 357-358 Inlay, definition, 478 Insole, definition, 479 Intensified Ultraviolet Viewer, latent impression detection, 11 Inventory, footwear evidence, 357-358 Inversion effect, photography, 53, 55 Iodine fuming enhancement procedure, 160 physical developer-enhanced impressions, 150 principle, 159-160

ludicial system, see Courts

K Known suspect foot impression, see Barefoot impression Known suspect footwear databases of known footwear, 284-285 obtaining shoes both shoes, 282 dating and initialing by examiner, 282-283 discretion, 279 importance o f obtaining shoes, 279 multiple shoe pair acquisition, 279-280 similar shoes owned by more than one suspect, 28 0 -2 8 1 photography, 285 preparation of evidence, 359 shoe box evidence, 283 test impressions Biofoam, 302 black ink print, 288-289 clay, 301-302 copy machine transparencies, 305-306 existing residue on black adhesive, 287 fingerprint powder and clear adhesive, 294, 296 fingerprint powder and gelatin lift, 296 fingerprint powder and oil coating, 296 fingerprint powder and roller transport film, 293-294 inkless methods, 292-293 Microsil, 300 negative impressions, 297-298

photographic transparencies, 304-305 polyvinylsiloxane, 298-299 rationale, 285-286, 306 record-keeping, 287 sand, 303-304 silicone casts, 302-303 talcum powder on black chartboard, 296 two-dimensional versus three-dimensional, 286-287, 298 variation between impressions, 304, 306 water-based ink and tracing paper, 291-292 Zetalabor, 298 treatment relative to other examinations, 283

Label, examination quality photography, 40 Lasts, shoe production, 183 LCV, see Leuco crystal violet Leuco crystal violet (LCV) blood staining reaction, 161-162 enhancement procedure, 163 formulation, 163 spraying of bloody crime scene, 160 Leuco malachite green, enhancement o f bloody footwear impressions, 173-174 Life expectancy, footwear impressions, 3-4 Lifting, see also Adhesive lift; Electrostatic lift; Gelatin lift; Microsil blood impressions, 124, 125 deformable impressions carpets, cushions, and grass, 128 paper, 127-128 sk in ,128-131,133 dental stone, 124 fingerprint powdering impressions, 126 grease or oiJ impressions, 124 indications and guidelines, 99-100, 103-104, 119 liquid silicone, 124 preparation o f evidence, 361-362 rationale, 99 technique determination factors, 100, 126-127 Lighting enhancement o f footwear impressions alternate light sources, 139-140, 144 cross polarization, 138 filters, 137 infrared light, 138-139 ultraviolet light, 138, 144 examination quality photography fill lighting, 49 natural or ambient light, 43 oblique light, 44-45,47-50, 52, 137

Index

493

reflected light, 43-44 three-dimensionaJ impressions, 44-45, 47-50 two-dimensional impressions, 50 point light source in test impression photography, 304-305 Luminol blood staining reaction, 169 longevity of stain, 170 time of staining, 169-170 nomenclature, 170 formulation, 170 enhancement procedure, 1 7 0 -171 photography of enhanced impressions, 171-173 second enhancements, 414

M Manufacture, shoes, see Cut process; Molding process Microsil blood impressions, 124 colors, 123 indications for lifting, 122 preparation and lifting, 122-123 test impressions of known footwear, 300 Molding process combined class characteristics from variations, 331-332, 333-334 compression-molded outsoles, see also Converse Chuck Taylor All-Star shoe expanded microcellular outsoles, 222,224 flash trimming and impression, 212, 214 mold warping, 215 multi-section molds for multi-color soles, 213-214 oversize unit soles, 222 pouring and molding, 210, 212 variation between molds, 215 injection-molded outsoles direct-attach process, 224,225-230 dual-density shoes, 224 mold requirements, 224 polyurethane outsole air bubbles, 230-235 unit soles, 224 mold making casting of shoe model, 200-201 computer-aided design-computer-aided manufacture, 199,218 electrical discharge machine, 200 hand-milled or hand-engraved, 199 insert accomodation, 201 significance to forensic casework, 208-210, 277

open-pour molding, 236-237 textures and surface treatments to mold surfaces acid etching, 204-205 casting from models, 207-208 factory coding, 208 hand stippling, 201,204 sand blasting, 205-206 Schallamach pattern differentiation, 208 smooth polished surfaces, 206 Moulage, casting, 66

N Naperville case background, 422 impression examination and court testimony, 422-424 manufacturer design differences, 425 non-identification o f shoe, 423-424 Negative impression, definition, 8 New York Gap store homicide case background, 416 impression matching with suspect shoe, 416-418 New York serial robbery/homicide case background, 425 snow impression evidence, 425-427 Nike Air Dynamic Flight shoe, production, 334 Nike Cortez blocker unit design, 260-261 variability, 4 18-4 19 Ninhydrin, enhancement of bloody footwear impressions, 169

o Open-pour molding, see Molding process Orientation, identifying characteristics, 335, 346 Overlooking, footwear impression evidence, 1-2, 17-18

Paper deformable impressions, 127-128 electrostatic lifting of footwear impressions, 127-128 footwear impression development from trace materials, 9 ink impression recording, 291-292

494

Footwear Impression Evidence, 2nd Edition

physical developer enhancement, 149 searching for footwear impression evidence, 11-12

Paraffin wax recommendations for casting, 65-66 snow impression casting, 92-93 Patent Blue, enhancement of bloody footwear impressions, 168 Pathfinder ESL, see Electrostatic lift PD, see Physical developer Photography adhesive lifts, 121-122 bare feet, 395 black lifting film impressions, 115 casting benefits over, 61-63, 65 enhancement of footwear impressions alternate light sources, 139-140,144 cross polarization, 138 filters, 137 high-contrast photography, 136-137 indications, 135-136 infrared light, 138-139 oblique light, 4 4 -4 5,47-50, 52, 137 ultraviolet light, 138, 144 evidence presentation in court, 377-378 examination quality photography cameras, 31-33 film, 34-35 focusing, 55-56 labels, 40 number of exposures, 50-52 procedure checklist, 58 snow impressions, 84 three-dimensional impressions, 44 -4 5 ,4 7 -5 0 two-dimensional impressions, 50 types of photographs, 27, 30 gelatin lifts, 121-122 general crime scene camera, 29 film, 29-30 relating footwear impression to scene, 30 types of photographs, 27 inversion effect, 53, 55 kit for crime scenes, 57 known suspect footwear, 285 lighting, see Lighting luminol-enhanced impressions attenuated light, 172-173 setup, 171 perspective problems, 364 preparation of evidence, 359, 361 scales bureau scale, 38 comparisons of quality, 38-39,41 importance of use, 35

length, 36 perspective checking aids, 36-37 physical characteristics, 37 surface qualities, 37 tripod, 40-42 types, 35-36 skin pattern injury, 129 success o f definite identification, 24 test impressions o f footwear, 304-305 Physical developer (PD) enhancement procedure, 148-150 formulation, 148 iodine fuming of enhanced impressions, 150 kit, 150, 152 paper impression enhancement, 149 reprocessing, 151 silver deposition, 147 wet footwear impression enhancement, 148 Plaster, definition, 68,69, 70 Plaster o f Paris, casting, 59, 65, 66, 67, 68, 70 Point light source, test impression photography, 304-305 Polyurethane outsole air bubbles case study, 428,430 characteristics, 235 chemical variables, 231-232 density dependence, 235 mechanical variables, 232-233 pattern-influenced bubbles, 233-234 source, 2 3 1 suspended bubbles, 234 direct-attach injection molding molding process, 224,225-230 reaction molding, 230-231 open-pour molding, 236-237 Polyvinylsiloxane, test impressions of known footwear, 298-299 Position, identifying characteristics, 335, 346 Positive identification case identifications, 352 characteristic number required for identification, 347-352 impression comparison design o f shoe, 367-368 individual identifying characteristics, 371-372 manufacturing characteristics, 368-369 shape and size, 369-370 side-by-side comparison, 366-367 superimposition, 366 wear characteristics, 370-371 non-conclusive results, reporting, 372-374 overview, 4, 24, 347 positive non-identifications, 366, 372 reporting, 372

Index

495

value of one confirmable random characteristic, 342-344, 347 Positive impression, definition, 8 Potassium thiocyanate enhancement procedure, 146-147 formulation, 145-146 iron reaction, 145 Primer, see Auto paint primer spray Probability, value of one confirmable random characteristic, 342-344, 347, 352

R Random identifying characteristics bare feet, 404 confirmation, 341 definition, 335, 349 value of one confirmable random characteristic, 342-344, 347, 352 wear, 350 Re-enforcement materials, casting, 76 Release agents, casting, 77-78

Safranin O enhancement procedure, 153-154 indications for use, 152-153 preparation, 153 St. CroLx homicide case background, 4 13 evidence collection, 4 13 luminol enhancement, 414 reconstruction of crime scene, 414-415 Sand, test impressions bare feet, 397 known footwear, 303-304 Sand blasting, outsole molds, 205-206 Scales, examination quality photography bureau scale, 38 comparisons of quality, 38-39,4 1 importance of use, 35 length, 36 perspective checking aids, 36-37 physical characteristics, 37 surface qualities, 37 types, 35-36 Scent recognition collection of evidence, 7 dog training, 7 Schallamach pattern definition, 317-318

differentiation from molding process patterns, 208 features, 318-319 sites of formation, 318 uniqueness, 318 Shape, identifying characteristics, 335, 346 Shoe box, evidence, 283 Shoe parts, terminology, 195 Silicone, see also Microsil casting, 65, 68 liquid silicone lifting, 124 test impressions of known footwear, 302-303 Simpson trial availability of evidence to prosecution and defense, 448 background, 431 Bruno Magli shoe design, 431-433 initial identification of impressions, 431-434 known impressions, 436 lasts, 439 manufacture, 434,435,438 molds, 438,445 photographic evidence of suspect ownership, 453-457 preparation of evidence for court, 436-437 sizing, 435-436,438-440 soles, use in other Italian shoes, 445-446 tracking of sales, 437,445,447 upper styles, 434-435 crime scene reconstruction from shoe prints, 443-445 elimination of non-footwear impressions, 440-441,442, 449-450, 452-453 elimination of officer footwear impressions, 440 evidence collection, 431,447 Lee's defense, 448-449 luminol enhancement of Bronco carpet, 441-442 news coverage of evidence in early stages, 431, 458 presentation of evidence, 446-447 reference footwear, 440 skin injury examination, 442-443 soil impression searching, 447 Siping cutting, 274, 276 definition, 272-273 variability, 273-274,276 Size, identifying characteristics, 335, 346 Sizing, footwear codings and markings, 191-195,208, 272 distribution o f sizes in United States population, 189-191 impression size correlation, 186, 188, 192 lasts, 183 measuring devices and measurements, 181-183

496 origin o f shoe sizing, 179 positive identification, 369-370 stature correlation, 186-J 89 systems American system, 180 Centimeter system, 180 conversions, 181 European system, 180 Mondopoint system, 181 terminology, 195 variability in shoe sizes among individuals, 184, 189-191 among manufacturers, 183-184, 185 Skin injury types, 128-12 photography, 129 quality of footwear impression, 130 shoe design identification from impression, 131, 133 Sneaker, history, 197-198 Snow impressions casting auto paint primer spray with dental stone, 94-96 conditions of snow, 96 dental stone pouring, 86-87 history, 84-85 melting, 88 paraffin wax, 92-93 snow print wax, 8 5 -86,87-88 sulfur casting, 88-92 photography, 84, 85 Sole manufacture, see Cut process; Molding process materials, 198 South Carolina homicide case background, 427 bloody shoe impression, 427-428,430 Static charge, footwear impressions, 7-8 Stature correlation with shoe size, 186-189 estimation from bare footprints, 407 Step length, gait analysis, 5 Stiple Converse Chuck Taylor All-Star shoe, 220 hand stippling, 201,204 Stitching shoe finishing, 270 sidewall and bottom variations, 276 Stride length, gaft analysis, 5 Stride width, gait analysis, 5 5-Sulfosalicylic acid, fixation o f bloody impressions, 161

Footwear Impression Evidence, 2nd Edition Superglue, see Cyanoacrylate fuming Superimposition, positive identification, 366 Suppliers, footwear evidence supplies, 483-486 Surface deformation, footwear impressions, 8

Talcum powder, black chartboard test impression, 296 Tartazine, enhancement of bloody footwear impressions, 169 Test impressions, known footwear Biofoam, 302 black ink print, 288-289 clay, 301-302 copy machine transparencies, 305-306 existing residue on black adhesive, 287 fingerprint powder methods clear adhesive, 294,296 gelatin lift, 296 oil coating, 296 roller transport film, 293-294 inkless methods, 292-293 Microsil, 300 negative impressions, 297-298 obtaining shoes for testing, see Known suspect footwear photographic transparencies, 304-305 polyvinylsiloxane, 298-299 positive identification design of shoe, 367-368 individual identifying characteristics, 371-372 manufacturing characteristics, 368-369 shape and size, 369-370 side-by-side comparison, 366-367 superimposition, 366 wear characteristics, 370-371 rationale, 285-286, 306 record-keeping, 287 sand, 303-304 silicone casts, 302-303 talcum powder on black chartboard, 296 two-dimensional versus three-dimensional, 286-287, 298 variation between impressions, 304, 306,362,365 water-based ink and tracing paper, 291-292 Zetalabor, 298 Tire tread, recycling in sole manufacture, 337 Toe bumper guard, variations, 221-222,272 Toes, see Foot Tracking signs, applications, 6-7 Tripod, examination quality photography, 40-42

Index

497 U

Underwater casting, 82 Upper, outsole positioning in shoe finishing, 269-270

V Vacuum Box, see Electrostatic lift Videography, bare feet, 395-396

W Walking base, gait analysis, 5 Water-to-powder ratio, gypsum casting, 70-71 Waxed surfaces, footwear impression evidence, 9, 20 Wear comparison between different shoes of same suspect, 328 degree of wear advanced wear compared to test impressions, 319- 320 correspondence with known impressions, 319 definition, 307 less wear compared to test impressions, 320- 322 forefoot wear, 310-312 general condition, 307, 326, 328 heel wear, 312-313, 325-326 identification and non-identification guidelines, 328 identifying characteristics, changes as shoe wear continues, 353-355 outsole wear, factors affecting design and manufacturing, 315, 326

foot anatomy, 308 foot function, 308-313 left versus right shoe, 315 occupation or habits, 314 surface exposure, 315 walking patterns, 3 14 weight, 314 position of wear correspondence with known impressions, 324 definition, 307, 322 spreading out o f wear, 322-323 positive identification, 370-371 Schallamach pattern definition, 317-318 features, 318-319 sites o f formation, 318 uniqueness, 318 uniqueness of patterns, 314-315 Wellman outsole cutting machine boots, 266-267 distribution of use, 262 materials for cutting, 262 templates, 263 variations in products, 263-266, 277 Welt, definition, 482 Wet origin impressions, overview, 14-17

X-ray, bare feet, 396-397

Zetalabor, test impressions bare feet, 394 known footwear, 298