Joe Nickell - Crime Science: Methods of Forensic Detection

CRIME SCIENCE

CRIME
SCIENCE

JOE NICKELL AND
JOHN F. FISCHER

THE UNIVERSITY PRESS OF KENTUCKY

Publication of this volume was made possible in part by a grant from the National Endowment for the Humanities.

Copyright 1999 by The University Press of Kentucky

Scholarly publisher for the Commonwealth, serving Bellarmine University, Berea College, Centre College of Kentucky, Eastern Kentucky University, The Filson Historical Society, Georgetown College, Kentucky Historical Society, Kentucky State University, Morehead State University, Murray State University, Northern Kentucky University, Transylvania University, University of Kentucky, University of Louisville, and Western Kentucky University. All rights reserved.

Editorial and Sales Offices: The University Press of Kentucky 663 South Limestone Street, Lexington, Kentucky 405084008 www.kentuckypress.com

1716151413 131211109

Library of Congress Cataloging-in-Publication Data

Nickell, Joe.

Crimc science : methods of forensic detection/Joe Nickell and John F. Fischers

p. cm.

Includes bibliographical references and index.

ISBN-10: 0-8131-2091-8 (cloth : alk. paper)

ISBN-13: 978-0-8131-2091- 1 (cloth : alk. paper)

1. Criminal investigation. 2. Forensic sciences. 3. Criminal investigation-Technological innovations. I. Fischer, John F. II. Title.

HV8073.N517 1998

365.25dc21

9830749

This book is printed on acid-free recycled paper meeting the requirements of the American National Standard for Permanence in Paper for Printed Library Materials.

Manufactured in the United States of America

Member of the Association of American University Presses

The authors are grateful to the following individuals for special assistance: Bill Schulz, Orlando Police Department, Orlando, Florida; Robert Miller, Phoenix Police Department, Phoenix, Arizona; Robert Ruttman, Mesa Police Department, Mesa, Arizona; and Marvin Stephens, Florida Department of Law Enforcement, Tallahassee, Florida.

The authors are also grateful to the following agencies for helpful cooperation: Orange County Sheriff's Office, Orlando, Florida; Mesa Police Department, Mesa, Arizona; Phoenix Police Department, Phoenix, Arizona; and the Orlando Police Department, Orlando, Florida.

Forensic means characteristic of, or suitable for, a court of law. Hence forensic science is a broad term that embraces all of the scientific disciplines that are utilized in investigations with the goal of bringing criminals to justice. The American Academy of Forensic Sciences defines it as the study and practice of the application of science to the purposes of the law. It includes such fields as forensic medicine, toxicology, psychology, and anthropology as well as the work of specialized examiners of fingerprints, firearms, tool marks, and questioned documents. The term is so broad as to include even criminology, a social science that plays a role in the administration of civil law.

This definition has since been adopted by the American Academy of Forensic Sciences.

At one time a criminalist might have been a generalist, but now most are specialists in one of many areas of expertise. These specialties include forensic chemistry, toxicology, drug analysis, serology, trace analysis, latent fingerprints, firearms examination, impression evidence, questioned document examination, and voice examination. Depending on the crime laboratory, some specialties may be combined with or separated from others. For example, because of the way they are compared, tool marks may be handled by the firearms examiner. Conversely, because of the increasing complexity of DNA analysis, it may be treated as a discipline separate from forensic serology, and crime scene examination may itself now be a specialized area of expertise.

In certain of the criminalistics disciplines, such as firearms examination and fingerprint identification, there is occasionally confusion between the terms identify and individualize. Although their respective Latin roots are similar (idem means the same and individus means not divisible), the terms are quite distinctive as they are correctly applied in criminalistics. As the great forensic authority Paul L. Kirk explains: The terms identification and identity are used constantly by practitioners in the field. Few stop to define the terms. Identity is defined by all philosophical authorities as uniqueness. Bowing to general scientific usage, we must however accept the term identification in a broader context referring only to placing the object in a restricted class.... In this sense, the criminalist would identify the object as a paint chip, but not relate it to the painted surface from which the chip was derived. He would identify a marking as a fingerprint, but without relation to the hand that placed it. Kirk raises an interesting point, noting that for the criminalist to use the word identification in its accepted context is to admit that there is no reason for his special existence . The criminalist does not attempt identification except as a prelude to his real functionthat of individualizing. The real aim of all forensic science is to establish individuality, or

Individualizationthat is, demonstrating the uniqueness of some item of evidenceis made possible by the fact that no two things in nature are exactly the same. Nearly everyone knows that this is true of snowflakes and fingerprints. But it is also true of gun barrels, lip impressions, shoe prints, and pieces of broken glass. The principle that all objects in the universe are unique may be expressed in many ways:

No two things that happen by chance ever happen in exactly the same way.

No two things are ever constructed or manufactured in exactly the same way.

No two things ever wear in exactly the same way.

No two things ever break in exactly the same way.

Of course, items made from a mold will be very similar to each other, and as a practical matter it may not be possible to individualize, say, the track of a brand new tire. If the impression was clear, however, it should be possible to identify its class characteristics, discovering which brand and model of tire the tread pattern came from. Over time, the tire acquires nicks, patterns of wear, and sufficient individual characteristics, making individualization possible. In the case of a new tread, one could only say that the track could have come from a certain automobilethat the track was consistent with it. In the case of a nicked and worn tire, the criminalist would be able to compare the questioned evidence (the tread imprint) with that of a known standard (the suspects tire or a test imprint made from it) to see whether or not the questioned impression may be individualized.

How many similarities are required to individualize an impression? In his book Individualization: Principles and Procedures in Criminalistics, Harold Tuthill writes, The individualization of an impression is established by finding agreement of corresponding individual characteristics by such number and significance as to preclude the possibility (or probability) of their having occurred by mere coincidence, and establishing that there are no differences that cannot be accounted for. Tuthill notes that the words an impression may be replaced by a bullet, handwriting, a break or fracture, or other wording appropriate to the evidence under consideration.