24mm

Rivers The Science of • Dahlem The Science of Forensic Forensic The Science of

David B. Rivers Gregory A. Dahlem Loyola University Maryland, Maryland, USA Northern Kentucky University, Kentucky, USA Entomology

Forensic entomology is one of the newest sub-disciplines to be recognized by international judicial systems in countries located on every continent. Arguably it deals with the most unpleasant of all disciplines— that feed on corpses. Though this text provides coverage of the three sub-fields of —urban, stored product, and medicocriminal—it is the latter that constitutes the core of the book.

The Science of Forensic Entomology builds a foundation of biological and entomological Forensic Entomology knowledge that equips the student to be able to understand and resolve questions concerning the presence of specific at a , at which the answers require deductive reasoning, seasoned observation, reconstruction, and experimentation—features required of all disciplines that have hypothesis testing at its core. Each chapter addresses topics that delve into the underlying biological principles and concepts relevant to the biology that forms the basis for using insects in matters of legal importance.

The book is more than an introduction to forensic entomology as it offers in-depth coverage of non-traditional topics, including the biology of masses, temperature tolerances of necrophagous insects, chemical attraction and communication, reproductive strategies of necrophagous , archaeoentomology, and use of insects in modern warfare (terrorism). As such, it will enable advanced undergraduate and postgraduate students the opportunity to gain a sound knowledge of the principles, concepts and methodologies necessary to use insects and other in a wide range of legal matters. David B. Rivers Gregory A. Dahlem

we h bs t i i t w e www.wiley.com/go/rivers/forensicentomology we ISBN 978-1-119-94036-4 h bs t i i t w e

Visit www.wiley.com/wiley-blackwell we h bs t i i t w e Also available as an e-book 9 781119 940364

The Science of Forensic Entomology

The Science of Forensic Entomology

David B. Rivers Loyola University Maryland Maryland USA Gregory A. Dahlem Northern Kentucky University Kentucky USA This edition first published 2014 © 2014 by John Wiley & Sons, Ltd.

Registered office John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK

Editorial offices 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030-5774, USA

For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell.

The right of the authors to be identified as the authors of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher.

Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book.

Limit of Liability/Disclaimer of Warranty: While the publisher and author(s) have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. It is sold on the understanding that the publisher is not engaged in rendering professional services and neither the publisher nor the author shall be liable for damages arising herefrom. If professional advice or other expert assistance is required, the services of a competent professional should be sought.

Library of Congress Cataloging-in-Publication Data Rivers, David, 1966– The science of forensic entomology / David B. Rivers, Gregory A. Dahlem. p. cm. Includes bibliographical references and index. ISBN 978-1-119-94036-4 (cloth : alk. paper) – ISBN 978-1-119-94037-1 (pbk. : alk. paper) 1. Forensic entomology. 2. Flies. 3. insects. 4. Postmortem changes. I. Dahlem, Gregory. II. Title. RA1063.45.R58 2013 614′.17–dc23 2013029868 A catalogue record for this book is available from the British Library.

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books.

Cover images: Front cover: Photo of a taken by Joseph Berger, Bugwood.org. Back cover: Photo of a bed bug from Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org. Cover design by Wiley

Set in 10/12pt Minion by SPi Publisher Services, Pondicherry,

1 2014 Contents

About the companion website xii Preface xiii

Chapter 1 Role of in criminal investigations 1 Overview 1 The big picture 1 1.1 What is forensic science? 1 1.2 Application of science to criminal investigations 3 1.3 Recognized disciplines in forensic science 9 Chapter review 10 Test your understanding 11 Notes 12 References cited 12 Supplemental reading 12 Additional resources 12 Chapter 2 History of forensic entomology 13 Overview 13 The big picture 13 2.1 Historical records of early human civilizations suggest understanding of insect biology and ecology 13 2.2 Early influences leading to forensic entomology 16 2.3 Foundation for discipline is laid through casework, research, war, and public policy 18 2.4 Turn of the twentieth century brings advances in understanding of necrophagous insects 21 2.5 Forensic entomology during the “great” wars 22 2.6 Growth of the discipline due to the pioneering efforts of modern forensic entomologists leads to acceptance by judicial systems and public 23 Chapter review 24 Test your understanding 26 Notes 26 References cited 26 Supplemental reading 27 Additional resources 27 Chapter 3 Role of insects and other arthropods in urban and stored product entomology 29 Overview 29 The big picture 29 3.1 Insects and other arthropods are used in civil, criminal, and administrative matters pertinent to the judicial system 29 3.2 Civil cases involve disputes over private issues 31 3.3 Criminal law involves more serious matters involving safety and welfare of people 31

v vi Contents

3.4 Administrative law is concerned with rulemaking, adjudication, or enforcement of specific regulatory agendas 32 3.5 Stored product entomology addresses issues of both a civil and criminal nature 33 3.6 Urban entomology is focused on more than just “urban” issues 38 Chapter review 42 Test your understanding 44 Notes 45 References cited 45 Supplemental reading 46 Additional resources 46 Chapter 4 Introduction to entomology 47 Overview 47 The big picture 47 4.1 Insecta is the biggest class of the biggest phylum of living organisms, the Arthropoda 47 4.2 The typical adult insect has three body parts, six legs, two antennae, compound eyes, external mouthparts, and wings 50 4.3 Tagmosis has produced the three functional body segments of insects: the head, thorax, and abdomen 51 4.4 Sensory organs and their modifications allow insects to perceive and react to their environments 55 4.5 The structure and function of an insect’s digestive system is intimately tied to the food that it prefers to eat 57 4.6 A tubular tracheal system transports oxygen to the body’s cells while moves through the body without the aid of a vascular system 58 4.7 The nervous system of insects integrates sensory input and drives many aspects of behavior 60 4.8 In order to grow, insects need to shed their “skin” 61 4.9 Many insects look and behave entirely differently as a than as an adult – the magic of metamorphosis 61 4.10 The desire to reproduce is a driving force for unique reproductive behaviors and copulatory structures in insects 62 Chapter review 64 Test your understanding 65 References cited 66 Supplemental reading 67 Additional resources 67 Chapter 5 Biology, taxonomy, and natural history of forensically important insects 69 Overview 69 The big picture 69 5.1 A variety of different insects and terrestrial arthropods are attracted to a dead body 69 5.2 The fauna of insects feeding on a body is determined by location, time, and associated organisms 71 5.3 Necrophagous insects include the taxa feeding on the corpse itself 72 5.4 Parasitoids and predators are the second most significant group of carrion-frequenting taxa 85 5.5 Omnivorous species include taxa which feed on both the corpse and associated arthropods 87 Contents vii

5.6 Adventitious species include taxa that use the corpse as an extension of their own natural habitat 89 Chapter review 90 Test your understanding 92 References cited 92 Supplemental reading 94 Additional resources 94 Chapter 6 Reproductive strategies of necrophagous flies 95 Overview 95 The big picture 95 6.1 The need to feed: anautogeny and income breeders are common among necrophagous Diptera 95 6.2 Size matters in production 98 6.3 Progeny deposition is a matter of competition 100 6.4 Larvae are adapted for feeding and competing on carrion 102 6.5 Feeding aggregations maximize utilization of food source 103 6.6 Mother versus offspring: fitness conflicts 104 6.7 Resource partitioning is the path to reproductive success 105 Chapter review 106 Test your understanding 108 Notes 109 References cited 109 Supplemental reading 111 Additional resources 112 Chapter 7 Chemical attraction and communication 113 Overview 113 The big picture 113 7.1 Insects rely on chemicals in intraspecific and interspecific communication 113 7.2 Chemical communication requires efficient chemoreception 114 7.3 Semiochemicals modify the behavior of the receiver 115 7.4 Pheromones are used to communicate with members of the same species 116 7.5 Allelochemicals promote communication across taxa 118 7.6 Chemical attraction to carrion 120 7.7 Chemical attraction to carrion by subsequent fauna 122 Chapter review 124 Test your understanding 127 Notes 127 References cited 127 Supplemental reading 129 Additional resources 130 Chapter 8 Biology of the maggot mass 131 Overview 131 The big picture 131 8.1 Carrion communities are composed largely of fly larvae living in aggregations 131 8.2 Formation of maggot masses involves clustering during oviposition or larviposition 132 viii Contents

8.3 Larval feeding aggregations provide adaptive benefits to individuals 134 8.4 Developing in maggot masses is not always beneficial to conspecifics or allospecifics 140 Chapter review 143 Test your understanding 145 References cited 146 Supplemental reading 149 Additional resources 149 Chapter 9 Temperature tolerances of necrophagous flies 151 Overview 151 The big picture 151 9.1 Necrophagous insects face seasonal, aseasonal, and self-induced (heterothermy) temperature extremes 152 9.2 Temperature challenges do not equal : necrophagous insects are equipped with adaptations to survive a changing environment 153 9.3 Life-history features that promote survival during proteotaxic stress 154 9.4 Deleterious effects of high temperatures on necrophagous flies 158 9.5 Life-history strategies and adaptations that promote survival at low temperatures 160 9.6 Deleterious effects of low-temperature exposure 166 Chapter review 167 Test your understanding 170 Notes 171 References cited 171 Supplemental reading 174 Additional resources 174 Chapter 10 Postmortem of human remains and vertebrate carrion 175 Overview 175 The big picture 175 10.1 Decomposition of human and other vertebrate remains is a complex process 175 10.2 Numerous factors affect the rate of body decomposition 177 10.3 When the heart stops: changes occur almost immediately but are not outwardly detectable 179 10.4 Body decomposition is characterized by stages of physical decay 184 Chapter review 187 Test your understanding 190 Notes 190 References cited 190 Supplemental reading 192 Additional resources 192 Chapter 11 Insect succession on carrion under natural and artificial conditions 193 Overview 193 The big picture 193 11.1 What’s normal about terrestrial decomposition? Typical patterns of insect succession on bodies above ground 194 11.2 Succession patterns under forensic conditions are not typical 196 11.3 Several factors serve as barriers to oviposition by necrophagous insects 198 Contents ix

11.4 The physical conditions of carrion decay can function as a hurdle to insect development 200 11.5 Insect faunal colonization of animal remains is influenced by conditions of physical decomposition 204 Chapter review 208 Test your understanding 211 Notes 211 References cited 212 Supplemental reading 214 Additional resources 214 Chapter 12 Postmortem interval 215 Overview 215 The big picture 215 12.1 The time since death is referred to as the postmortem interval 215 12.2 The role of insects in estimating the PMI 217 12.3 Modeling growth–temperature relationships 220 12.4 Calculating the PMI requires experimental data on insect development and information from the crime scene 222 12.5 The evolving PMI: changing approaches and sources of error 227 Chapter review 230 Test your understanding 232 Notes 233 References cited 233 Supplemental reading 235 Additional resources 235 Chapter 13 Insect alterations of bloodstain evidence 237 Overview 237 The big picture 237 13.1 Bloodstains are not always what they appear to be at the crime scene 237 13.2 Science is the cornerstone of bloodstain pattern analyses 238 13.3 Crash course in bloodstain analyses 240 13.4 Insect activity can alter blood evidence 243 13.5 Insect feeding activity on bloodstains or fresh blood can yield regurgitate spots or transference 243 13.6 Digested blood is eliminated from insects as liquid feces or frass 245 13.7 Parasitic insects can confound blood evidence by leaving spot artifacts 246 Chapter review 246 Test your understanding 248 Notes 248 References cited 249 Supplemental reading 249 Additional resources 250 Chapter 14 Necrophagous and parasitic flies as indicators of neglect and abuse 251 Overview 251 The big picture 251 14.1 Parasitic and necrophagous flies can infest humans, pets, and livestock 252 14.2 Not all forensically important insects wait until death to feed 253 x Contents

14.3 Chemoattraction of flies to the living does not necessarily differ from the odors of death 255 14.4 Necrophagous and parasitic flies display oviposition and development preferences on their vertebrate “hosts” 257 14.5 Larval myiasis can be fatal 258 Chapter review 261 Test your understanding 263 Notes 263 References cited 264 Supplemental reading 265 Additional resources 266 Chapter 15 Application of molecular methods to forensic entomology 267 Overview 267 The big picture 267 15.1 Molecular methods: living things can be defined by their DNA 267 15.2 Evidence collection: preserve DNA integrity 270 15.3 Molecular methods of species identification 270 15.4 DNA barcoding protocol 275 15.5 Problems encountered in barcoding projects 279 15.6 Gut content: victim and suspect identifications 280 15.7 Molecular methods and population genetics 281 15.8 Molecular methods: non-DNA based 282 15.9 Validating molecular methods for use as evidence 284 15.10 Future directions 284 Chapter review 285 Test your understanding 287 References cited 288 Supplemental reading 291 Additional resources 292 Chapter 16 Archaeoentomology: insects and archaeology 293 Overview 293 The big picture 293 16.1 Archaeoentomology is a new “old” discipline 293 16.2 Concepts and techniques from forensic entomology can be applied to archaeology 295 16.3 Ancient insects and food: connection to stored product entomology 296 16.4 Ancient insects as pests: beginnings of synanthropy and urban entomology 298 16.5 Ancient insects and mummies: revelations about past lives and civilizations 301 16.6 Forensic archaeoentomology: entomological investigations into extremely “cold” cases 304 Chapter review 304 Test your understanding 306 Notes 307 References cited 307 Supplemental reading 309 Additional resources 309 Contents xi

Chapter 17 Insects as weapons of war and threats to national security 311 Overview 311 The big picture 311 17.1 Terrorism and biological threats to national security are part of today’s world 312 17.2 Entomological weapons are not new ideas 314 17.3 Direct entomological threats to human populations are not all historical 316 17.4 Impending entomological threats to agriculture and food safety 318 17.5 Insect-borne diseases as new or renewed threats to human health 319 17.6 Insects can be used as tools for national security 321 Chapter review 324 Test your understanding 327 Notes 328 References cited 328 Supplemental reading 329 Additional resources 329 Chapter 18 Deadly insects 331 Overview 331 The big picture 331 18.1 Insects that bite, sting or secrete cause fear, loathing, and death 332 18.2 Insects that cause death 333 18.3 Human envenomation and intoxication by insect-derived toxins 338 18.4 Insects that injure humans rely on chemically diverse venoms and toxins 338 18.5 Non-insect arthropods that should scare you! 342 18.6 Implications of deadly insects for forensic entomology 345 Chapter review 346 Test your understanding 349 Notes 349 References cited 350 Supplemental reading 351 Additional resources 351 Appendix I Collection and preservation of calyptrate Diptera 353 Collecting adult flies 353 Collecting fly larvae 355 Mounting and preserving specimens (adult flies) 355 References cited 357 Resources and links 357 Appendix II Getting specimens identified 359 Morphological identification of specimens on your own 359 Identification of specimens (by systematic expert) 360 References cited 361 Resources and links 361 Appendix III Necrophagous fly life table references 363 Glossary 367 Index 377 CHECK OUT THE COMPANION WEBSITE FOR

The Science of Forensic Entomology

by visiting www.wiley.com/go/rivers/forensicentomology

Click now and gain access to

■■ Downloadable versions of the illustrations within the book

■■ Downloadable versions of the tables within the book Preface

Welcome to the endlessly fascinating world of insects! For most people, insects are creatures that simply Science and crime annoy. They buzz around at picnics and the beach, landing unwelcome on food, taking a plunge into cans Obviously all crimes do not involve death. Nor are all of soda, or drawing blood from an arm or leg. These legal matters necessarily criminal in nature. Yet homi- ravenous beasts can destroy our food when attacking cides, more correctly corpses, attract the undivided crops (Figure 1) or if they simply invade a kitchen attention of many insects, and us. Death is utterly cap- pantry. Insects can also vector many devastating dis- tivating. There is simply no denying it, particularly eases to humans, pets, and livestock, yielding high when foul play is suspected. Despite the fact that death mortality rates in several regions of the world due to homicide, negligence, or accidents represents (Figure 2). Based on these wonderful experiences, a some of the worst outcomes associated with human simple definition of an insect to the lay community interaction, humans are drawn to the macabre. A probably reads something like “a multilegged ‘worm’ or quick survey of television programming (Table 1) on ‘bug’ that is gross, slimy, and which bites humans at any given night in the confirms the every opportunity.” The necrophagous activity of attraction. Why the public interest? A discussion of insects on animal carcasses (carrion), including human human nature and psyche is far beyond the scope of corpses, probably does little to alleviate this view. this book, but the attraction is real. Jack the Ripper Fascinating world of insects? Yes indeed! The can perhaps be credited as the first figure to capture biology of Insecta is unmatched by any other group of public attention because of the heinous he animals, particularly when taking into account the committed (Figure 3). There was (is) something so species richness of terrestrial and aquatic environ- intriguing (and frightening) about those grotesque ments. Insects are highly adaptable in all life-history mutilations in the Whitechapel district of London in characteristics, including morphology, physiology, and 1888 that it has led to movies, documentaries, and behavior; display multiple lifestyles that can change hundreds of books and articles about the murderous with development; are attuned to seasonal change and Ripper. respond with highly evolved genetic programs that The great fictional detective Sherlock Holmes promote survival; utilize several forms of locomotion, (Figure 4) may well be responsible for introducing including flight (shared only with birds and bats), deductive reasoning and scientific methodology to aquatic propulsion and jumping (some maggots liter- criminal investigation. Certainly arguments can be ally grab their posterior end with their mouth to propel made for landmark activities of many others before upward); and show amazing efficiency at such tasks as and after Sir Arthur Conan Doyle’s foray into nine- food acquisition, nutrient assimilation, wound healing teenth-century detective work, yet the mass appeal of and fertilization. In the words of the immortal lab Holmes and his faithful sidekick Dr John Watson are Brain (of the cartoon Pinky and the Brain2), insects undeniable and Conan Doyle’s understanding of the have achieved “world domination.” linkage between science and crime were, at the very This text explores the incredible world of insects from least, cutting edge for the time. Few police forces incor- a uniquely applied view: the intersection of insect biology porated elements of forensic analyses in criminal with the judicial system. Each chapter addresses a specific investigations at the time of Conan Doyle and Holmes. topic of forensic science or forensic entomology, delving Today, the use of scientific approaches, analyses and into the underlying biological principles and concepts interpretations of crime scenes and physical evidence relevant to insect biology that form the bases for using has become commonplace. Modern investigations rely insects to help resolve legal issues. on forensic science – the application of the scientific

xiii xiv Preface

15

10

5 Estimated annual economic costs (damage + control efofrts) inbillions of dollars

0 Flea s Termite s Fire Boll weevil Mosquitoes Gypsy pine Grain weevels Corn rootworms

Insect species Asian citrus psyllid s

Figure P.1 Estimates of economic impact (insect damage and cost of control) on an annual basis of several global insect pests. Data derived from Kiplinger Agricultural Letter (July, 2011) and Texas Boll Weevil Eradication Foundation. method and analyses involving a broad spectrum of ­geographic location, and a series of other abiotic and disciplines associated with life, physical and social biotic influences, the species of insects that arrive on a ­sciences – to resolve questions associated with the legal body and the rate of development are relatively pre- or judicial system. An in-depth discussion of the role dictable. These features of the life-history strategies of of forensic sciences in criminal and civil matters is several species of necrophagous insects are the bases ­presented in Chapter 1. Eleven major subdivisions of for using insects in investigations of suspicious forensic science are recognized by the American or ­homicides and fall under the umbrella of medico- Academy of Forensic Sciences (http://aafs.org), with legal or medicocriminal entomology. The latter is over 31 subdisciplines providing some form of expert becoming the accepted name for the branch of forensic analysis in legal cases. Forensic entomology is one of entomology where evidence is used in the newest subdisciplines to be accepted into the criminal cases, frequently those associated with judicial system and as such is also one of the smallest violent acts. This subdiscipline is the one most often in terms of trained experts. referred to when mentioning forensic entomology. However, the field is subdivided into three distinct areas: urban entomology, stored product entomology, Bugs, thugs, and scientists and medicocriminal entomology. Urban entomology is predominantly focused on insects that interact Several species of insects are attracted to carrion, a with humans in residential or commercial settings, term used to describe the carcass of a dead animal including the property associated with these facilities. at any stage of decay. Depending on the season, It is not defined by geographic location (i.e., in munic- Preface xv

Chagas’ disease (household bugs) 100 million

Dengue (mosquitoes) 2500 million Malaria (mosquitoes) 500 million

Plague (fleas) & Leishmaniasis (sand flies) Sleeping sickness 350 million (tsetse fly) >100 million

Figure P.2 Estimates of human risk worldwide to insect-borne diseases. Insect vectors are given in parentheses. Data from the 1996 World Health Organization report The State of World Health.

Table P.1 Popular crime and forensic investigation based ipalities versus rural) as the term “urban” implies. television shows. Stored product entomology deals with insect infesta- tion of food and food products and the disputes that Program Television network result from the presence of insects, their body parts or Bones FOX obvious damage from their activity in foodstuffs. No matter how tolerant­ you are of insects, few people will CSI series CBS tolerate food that has been infested with insects. The CSI: Crime Scene Investigation thought of insect frass (otherwise known as excre- CSI: New York ment) in an energy bar or breakfast cereal, or CSI: Miami parts floating to the top of a pot of boiling pasta, tends Cold Case CBS to gross the average person out, and may lead to civil Criminal Minds CBS suits against the manufacturer, food distributer, and/ Dexter Showtime or grocer. Forensic Files truTV Though all three branches of forensic entomology Law & Order: SVU NBC are important and require trained experts to investi- The Mentalist CBS gate civil or criminal matters involving insects, the Monk USA focus of this text is on aspects of medicocriminal ento- NCIS series CBS mology. Chapter 5 introduces some of the most common insects frequenting corpses, whether indoors NCIS: Naval Crime Investigative Service or outdoors. Necrophagous flies in the ­families NCIS: Los Angeles and Sarcophagidae are usually among Psyche USA the most important insects to serve as evidence­ in cases Shows are broadcast in the United States and most appear in syndication in of suspicious deaths or homicides and consequently addition to new programming each television season. receive special attention in Chapters 6–9, detailing xvi Preface

Figure P.3 Jack the Ripper taunted London police by writing letters to them acknowledging his crimes and detailing plans for more murders. His letters also spawned copycat authors, including this letter that was sent to to the “Detective Offices” of Scotland Yard on 9 October 1888. This information is licensed under the terms of the Open Government Licence http:// www.nationalarchives.gov.uk/doc/open-government-licence (www.department.gov.uk/document, accessed 22 October 2011).

their reproductive strategies, chemical attraction to carrion, group feeding behavior in maggot masses, and temperature tolerances as adults and juveniles. Other chapters focus on the biology of postmortem decay (Chapter 10), the ecological succession by insects that occur in terrestrial and aquatic environments (Chapter 11), how to use insect succession on carrion to calcu- late a minimum postmortem interval (Chapter 12), and insect contamination of bloodstains (Chapter 13). Later chapters focus on unique topics to forensic ento- mology, with an examination of insect utility in ­archaeological exploration (Chapter 16), the impor- tance of insects in issues of national security and ter- rorism (Chapter 17), and an examination of insects and other arthropods that can be deadly to humans (Chapter 18).

How to use this textbook

The aim of this textbook is to serve as a tool for stu- Figure P.4 The unmistakable silhouette of Sherlock dent learning. Central to that aim is that this book is Holmes. Reproduced with permission of © The Sherlock focused not as a training guide for practitioners, but Holmes Museum, 221b Baker Street, London, England, www. rather is designed to explore the fundamental concepts sherlock-holmes.co.uk. and principles underlying the discipline of forensic Preface xvii entomology. To achieve those goals, the book has been develop the conceptual idea. At the end of each chapter, organized into topics of significance to the field and the “big picture” is presented again, only as a more that allow an examination of general and advanced developed outline with key facts and ideas presented concepts of biology and entomology. Within this orga- along with the key concepts. In the truest since, these nization, the body of the text is arranged to build a outlines can serve as study guides for the chapters, foundation of biological and entomological knowledge although the level of detail to be expected for an exam that allows you to address questions associated with or quiz will likely be less than expected by an instructor. forensic entomology. Armed with this background, Key terms are set in bold when mentioned for the first you should be equipped to tackle inquiry-based time in the book. Students should learn these terms as learning, such as attempting to answer applied ques- they represent part of the working vocabulary associ- tions concerning the presence of specific insects at a ated with forensic entomology. The emphasis of this crime scene, where the answers require deductive book will not be on the terms, but instead on the con- reasoning, seasoned observation, reconstruction, and cepts and application of ideas to solving biological experimentation. questions. Questions are included at the end of each chapter so that students can monitor their progress with Organization learning the material presented. In most chapters, a series of questions following Bloom’s taxonomy will The Science of Forensic Entomology is organized into be given so that assessment of rote memorization, 18 chapters that can be explored in any order. The only conceptual understanding, application of ideas and prerequisite is that for students lacking any kind of concepts, and synthesis can be self-assessed. Typically, entomological background, it is recommended that questions will progressively become more challenging, you first review Chapter 4 before diving into the more with the latter ones more consistent with higher-order advanced entomological topics covered in Chapters learning. 6–18. The early chapters function as an introduction to forensic science (Chapter 1), the history of forensic entomology (Chapter 2), and the role of insects in Study materials legal investigations (Chapter 3). Each chapter is orga- nized into a brief overview of the contents, followed by Additional information can be found at the end of each “The big picture” – a list of key concepts or ideas to be chapter to aid in student learning and allow for further presented in the book – followed by in-depth exploration of topics. A supplemental reading list is discussion of the concepts and ideas. At the end of found after the references cited section and provides­ each chapter is a representation of the “big picture” more in-depth coverage of topics that oftentimes are concepts and ideas along with at least two to three key only superficially dealt with in a given chapter. URL points. Questions, references cited, a supplemental addresses for websites that provide information on reading list, and a list of other useful resources (i.e., additional readings, topics, or organizations related to websites, organizations) are also included at the end of chapter topics will follow the supplemental reading list. each chapter. Because a single resource like this text is not sufficient to do full justice to forensic entomology, students are encouraged to review this information as a means to Pedagogy fully engage in the fascinating world of insects and the field of forensic entomology. With any textbook you have likely encountered, the reading is not meant to work like a novel in which you are compelled to read cover to cover. There are several Notes points of entry to this text, so to aid you in finding the meat of each chapter, key concepts are listed at the 1. Pinky and the Brain was an animated cartoon that first front as “The big picture.” Each of these concepts or ­appeared in the series Animaniacs and later starred in their ideas serves as the subheadings throughout the text, own cartoon series (1995–1998) on the WB television with the content under a subheading designed to network.­

Chapter 1 Role of forensic science in criminal investigations

Forensic Science is no longer on the fringes of criminal investigations. Science is solving cases that otherwise remain unsolved. Science is identifying the guilty with a certainty that protects the innocent at the same time. The Honorable John Ashcroft, former Attorney General of the United States1

Overview 1.1 What is forensic

Before an in-depth discussion of forensic entomology science? can really begin, there is a need to define the relationship between this discipline and the broader field of forensic Science is used to solve crimes. In fact, it is ­instrumental science. As the name implies, science is the core of in resolving cases involving both civil and criminal forensic analyses. It is only fitting, then, that Chapter 1 issues, particularly those of a violent nature. Not begins with an exploration of the application of science ­surprisingly, crime too has become more sophisticated, to legal matters, which also serves as a simple working with today’s criminals relying on aspects of ­science to definition of forensic science. Throughout the chapter, threaten individual and national security. One has to emphasis will be placed on the use of the scientific look no further than bioterrorism to see a clear linkage method in all forms of forensic analyses, from the pro- between scientific understanding and violent criminal cess of analyzing physical evidence to understanding the activity. This chapter is devoted to understanding the types of outcomes associated with forensic analyses. The relationship between science and criminal investiga- different specialty areas of forensic science will be dis- tions. Particular attention is given to understanding cussed to allow a perspective of the broad impact of sci- the , a defined way of doing science, ence on criminal and civil investigations. as it serves as the core principle for studying natural phenomena and in forensic analyses. Forensic science has become a broad term, depart- The big picture ing somewhat from the simple definition given earlier in which it was stated to be the application of science •• What is forensic science? to law. The term “forensic” is defined as pertaining •• Application of science to criminal investigations. to or connected with the law, while “science” is the •• Recognized specialty disciplines in forensic science.­ study of the physical and natural world through

The Science of Forensic Entomology, First Edition. David B. Rivers and Gregory A. Dahlem. © 2014 John Wiley & Sons, Ltd. Published 2014 by John Wiley & Sons, Ltd. Companion website: www.wiley.com/go/rivers/forensicentomology

1 2 The science of forensic entomology

Table 1.1 Specialized areas of forensic science recognized by the American Academy of Forensic Sciences (AAFS).

Section Membership totals*

Criminalistics 2571 Figure 1.1 A knife found at a crime scene is an example of Digital + Multimedia Sciences 90 physical evidence. Photo by Ricce. Image available in public Engineering Sciences 157 domain at http://commons.wikimedia.org/wiki/File:Knife_ Fox.jpg General 702 Jurisprudence 189 Odontology on the internet or in some dictionaries yields results 429 which indicate that “forensics” can also be defined as Pathology/Biology 878 referring to the law. In today’s society, practice tends to Physical Anthropology 423 set policy or norms and, as such, “forensics” is quickly Psychiatry/Behavioral Science 135 becoming an accepted term for forensic science. No Questioned Documents 198 doubt this expanding definition has its origins with Toxicology 516 the popular television crime shows. Yet another impact of the rising popularity of *Membership data as of July 8, 2011 at http://www.aafs.org/sections. Forensic entomologists typically belong to the Pathology/Biology section of AAFS. forensic science through television programming is the phenomenon known as the CSI effect (Saferstein, 2011). The name is derived from the very popular ­systematically arranged facts and principles that are ­television series CSI: Crime Scene Investigation (airing rigorously tested by experimentation. When used on the CBS network). In general terms, the increased together the two terms yield a discipline that addresses public attention to forensic science is usually linked issues ­pertaining to or connected to the law through to this TV series. However, there are numerous other the application of tested facts and principles and by influences that have contributed to the soaring popu- use of rigorous experimentation. As mentioned previ- larity. Regardless of the source of influence, the public’s ously, the definition of forensic science has become perception of what science can do for a criminal more encompassing, now representing a vast array ­investigation has become distorted. Many individuals, of medical, scientific (natural and applied) and social including those who potentially serve as jurors, have scientific disciplines (Table 1.1). So now we may revise become convinced from TV shows that when the our definition of forensic science to reflect modern, experts (i.e., forensic scientists) are called in to broader approaches: “the use of scientific knowledge ­investigate a crime, they will always find physical evi- and technologies in civil and criminal matters, dence and that detailed analyses in the crime lab, using including case resolution, enforcement of laws and real and imaginary technologies2, will ultimately solve national security.” The term criminalistics is commonly the crime by identifying the perpetrator (Figure 1.1). used to narrow this broader definition into the specific When delays occur during an investigation or when activities of a crime or forensic laboratory (Gaensslen there is simply little or no evidence to go on, the et al., 2007). Most aspects of applying science to the law, victim(s), families and even jurors become frustrated including those associated with forensic entomology, and believe the problem is the incompetence of the fall under the umbrella of criminalistics. investigative team. After all, it only takes 1 hour for the Use of the term “forensics” as a substitute for CSI team to examine the crime scene, find evidence, “forensic” has confused the terminology to some degree. analyze it, identify suspects, interview the suspects, The former term originally meant the study or art of and seal a full confession! This impressive effort is usu- debate or argumentation. Hence, a school debate team ally achieved by only one or two people, who perform practices forensics or debating. Though “debate” bet- all the functions that in real life would normally require ween attorneys has a defined role in the courtroom, it a team of individuals. Of course, in reality the process does mean pertaining to the law. However, within the is much more time-consuming, requiring many indi- court of public or popular opinion, “forensics” has viduals working together, and often a crime goes come to imply forensic science. In fact, a word search unsolved. When television fantasy is not separated Chapter 1 Role of forensic science in criminal investigations 3 from reality, the result is that unrealistic expectations ­disciplines may incorporate aspects of scientific inquiry are placed on law enforcement officials based on the into their curricula but the approaches are not the core public’s belief that television reflects the real world of of the training as is common in the natural sciences. forensic science and criminal investigations. Thus, our attention will be directed to what forensic The reality is that the application of science to legal scientists do when trained in the natural sciences.­ matters can profoundly influence the resolution of a The major functions performed by a forensic ­scientist crime. However, there are limitations to what can and include analysis of physical evidence, providing expert cannot be done, some of which will be addressed later testimony to the court and, in some cases, collection of in this chapter. The real value of science in legal mat- evidence at a crime scene. Details of evidence collection ters is that it relies on validation via scientific inquiry go beyond the scope of this ­textbook and the reader using the scientific method. The scientific method should consult such excellent works as Saferstein is the key, as its use requires adherence to defined (2011) and Swanson et al. (2008) for a general discussion ­unbiased approaches to designing, conducting, and of crime scene techniques, and Haskell and Williams interpreting experiments. Human emotions or desires, (2008) and Byrd and Castner (2010) for information as well as error, are minimized so that the facts, or specific to the collection of insect and arthropod truths in the case of law, can come to light. A more ­evidence. The majority of this section will focus on detailed discussion of the scientific method can be analyses of physical evidence. However, before discuss- found in section 1.2.3. ing the means of forensic analyses, we need to spend some time determining what is physical evidence. Application of science 1.2 1.2.1 Physical evidence to criminal investigations Physical evidence is any part or all of a material object What can forensic science do to help in civil and used to establish a fact in a criminal case. Items as criminal cases? Or more to the point, what do forensic diverse as bullet casings, bone fragments, a dental scientists do? Forensic investigation is used to address crown, matches, or fly maggots can serve as physical numerous issues associated with criminal, civil and evidence. Each is a physical object that may be directly administrative matters. Indeed, most forensic scien- related to a violent act that has been committed or that tists actually work on cases of a civil or administrative results from a criminal deed. It is this physical evi- nature, or deal with issues related to national security dence that a prosecutor must use to “prove” the ele- such as those under the umbrella of the Department of ments of a case, or corpus delicti, to a jury beyond a Homeland Security in the United States (Gaensslen reasonable doubt. Proving something true is contrary et al., 2007). The focus of this book is medicocriminal to the training of a scientist well versed in the scientific entomology, so the emphasis in this chapter is placed method, and thus a forensic scientist faces an ethical on criminal matters. challenge to stay focused on facts or data and not to So how do forensic scientists contribute to criminal make absolute statements more inclined to come investigations? In section 1.1 we spent some time from an attorney. Some of the work of the forensic ­discussing what they cannot do: solve crimes as on CSI. ­scientist is to help establish the elements of the case. In real cases, forensic scientists spend the majority of For example, in a scenario in which a police officer their time applying the principles and methodologies of confiscates a brown powder from a suspect or alleged their discipline to the elements of the crime. In other criminal, it is the job of a forensic chemist or toxi­ words, a great deal of time is devoted to using the cologist to determine whether the powder is a narcotic scientific method. Interestingly, training in scientific like heroin, in which case a crime has been committed, inquiry is not a universal feature of the curricular or whether it is some other substance. In most ­pedagogy of all the disciplines contributing to forensic instances, however, forensic analyses are performed on science. Graduates in traditional science subjects such an object or material collected from what has already as biology, chemistry and physics (collectively referred been determined to be a crime scene. to as the natural sciences), and even geology, are trained In contrast, some evidence is the result of the inter- in rigorous use of the scientific method. Other action that occurs between individuals, presumably the 4 The science of forensic entomology

Fly spots

Blood stains

Figure 1.2 Human hair is a common form of found at a crime scene or on a victim. Photo by Edward Figure 1.3 Bloodstains and fly spots or artifacts are virtu- Dowlman. Image available in public domain at http://­ ally undistinguishable from each other. Photo by D.B. Rivers. commons.wikimedia.org/wiki/File:Human_Hair_10x.JPG victim and assailant. According to Locard’s exchange Crime scene principle, every contact between individuals leaves a trace; that is, physical contact between two individuals will inevitably lead to transference of materials that can Crime scene investigator/officer serve as trace amounts of physical evidence (Gaensslen et al., 2007). These minute amounts of materials are Police crime lab Medical examiner referred to as trace evidence and can include such (Coroner) items as hairs, clothing or fabric fibers, gunshot residue, Forensic laboratory bloodstains, and other types of body fluids (Figure 1.2). Entomological trace ­evidence is not common but can include fly spots (regurgitate containing corpse’s Court blood), insect artifacts (similar to fly spots), and frass on a body left by necrophagous insects (Figure 1.3). Figure 1.4 Chain of custody of physical evidence ­collected at a crime scene. The open arrows designate 1.2.2 Collection of evidence points along the chain where a forensic scientist may be involved. Modified from Jackson & Jackson (2008). Details of proper methods of evidence recovery will not be covered in this textbook. What is important to the evidential object has been at all times and is emphasize is that before any evidence is sent to a referred to as continuity of evidence. The group of forensic laboratory for further analysis, the physical individuals responsible for maintaining continuity of evidence collected at a crime scene must be properly evidence during a criminal investigation is termed the maintained. In this respect, evidence from a crime chain of custody and a typical evidence progression scene must be accounted for during the entire process is illustrated in Figure 1.4. of investigation, from the time the physical or trace evidence is recovered at a crime scene and analyzed at a forensic laboratory until the evidence is presented 1.2.3 The scientific method in the courtroom by expert witnesses, many of whom is the key to forensic analyses are the forensic scientists conducting the analyses. The “accounting” is in the form of paperwork that provides Scientific inquiry using the scientific method is the a complete flowchart showing with whom and where foundation for the natural sciences as well as forensic Chapter 1 Role of forensic science in criminal investigations 5 science. More generally, science is a process of asking questions about natural phenomena and then seeking the answers to those questions. Scientists as a whole are inquisitive in nature and it is this core make-up that leads individuals to study a particular scientific discipline. Asking questions is one feature of scientific inquiry. Asking the right questions in the right way and then designing means (experiments) to test those questions is what scientists do (Barnard et al., 1993). Anyone can ask questions and try to find the answers. However, testing questions using an approach centered on formulating hypotheses, making observations from carefully designed experiments, refining questions, and narrowing possible explanations is a skill that is learned or acquired from rigorous training. The Figure 1.5 Tire treads pressed into mud, dirt or sand can ­process outlined is referred to as the scientific method, represent a scene impression found at a crime scene. Photo a systematic approach or procedure for investigating by D.B. Rivers. natural phenomena. Simply stated, it is a defined way of doing science. Not everyone is trained in the 3. Has the information been peer reviewed and scientific method, including many who engage in published? forensic analyses. Such training is typically associated 4. What is its general acceptance by other scientists in with education in the natural sciences. The inherent the same field? value of the scientific method to scientists is that it provides a roadmap for conducting scientific investi- The process of scientific inquiry is straightforward gations and also serves as a means for peers in the and use of the scientific method is not meant to be scientific community to scrutinize research in their intimidating. That said, asking the right questions respective fields. It can be viewed, then, as a means of in the right way generally requires a fundamental validation of results (observations), methodology, and understanding of the phenomena or organisms to be explanations. In the applied world of forensic science, observed as well as practice in developing the skill the scientific method provides not only validation but of scientific inquiry. If you are not convinced that also a systematic approach for distinguishing between scientific investigation is a skill that is developed, read alternate hypotheses for elements of a crime. through any research journal and compare the The scientific method is our way to really understand “quality” of the experiments detailed. cause-and-effect relationships in the world around us. The scientific method can be broken down into Carefully crafted, controlled experiments allow scientists specific steps that can be followed much like a flow- to move beyond observed correlations between one vari- chart (Figure 1.5): able and another to a real understanding of the under- lying causal relationships (or a realization that two events, 1. Make observations that lead to lead to questions. while correlated, are not intimately linked to each other). Observing a natural phenomenon generally leads to Research, especially published research, provides formulation of questions: Why did this happen? How the background for quality scientific testimony in the did this happen? Will it happen again? The latter­ courtroom. The landmark ruling by the United two questions can lead to the development of expla- States Supreme Court in Daubert v. Merrell Dow nations that can be tested by the scientific method, Pharmaceuticals, Inc. provides a framework for judges but not necessarily the former. “Why” questions to assess the scientific opinion. The decision provides imply evolutionary meaning and, while fun for spec- guidance by establishing four criteria to assess scientific ulation, often cannot be framed, at least not simply, testimony (Faigman, 2002): in a manner that allows experimental testing. 2. Formulation of hypotheses. The “right” or “good” 1. Is the information testable and has it been tested? question is one that lends itself to being tested. 2. What is the error rate and is that error rate acceptable? What is tested is not the question directly, rather 6 The science of forensic entomology

the explanation that has been formulated to control variables. Only carefully controlled experi- account for the initial observation. In other words, ments allow an investigator to examine the impact of an educated guess or explanation of the initial one variable alone on the condition being examined. observation or phenomenon, which is called a 4. Evaluating observations or data. Once the observa- ­hypothesis. Scientists are trained to develop mul- tions have been made, it is imperative that the sci- tiple hypotheses to explain a phenomenon and entist or investigator thoroughly interprets the data then design experiments that can test each of these collected. In many cases this involves a series of explanations. Formulation of good hypotheses is comparative evaluations (addressed in more detail often based not only on the researcher’s observa- in section 1.2.4) with other data in the scientific lit- tions but also on a comprehensive knowledge of erature, databanks, test or voucher specimens (a information that has been published on similar sit- specimen archived in a permanent collection serv- uations in the past. Science builds on the work of ing as a reference for a taxon), or other resources. past scientists. Here lies the key to hypothesis The data are also evaluated by statistical analyses to formation: a good ­hypothesis is one that is testable determine if what has been observed differs signifi- by experimentation. If after conducting a well- cantly from what was predicted or from other treat- designed experiment the investigator cannot ments. Statistical analyses require that the investigator support or refute the hypothesis,­ it was not a good understand the type of data to be collected prior to one to begin with. Conversely, the results of an initiating the tests so that the experimental deign is experiment can falsify a hypothesis, meaning that appropriate for the data and statistical test to be used. the data generated do not support the explanation 5. Refining hypotheses. After careful evaluation of the for the original observation, but a hypothesis can data, the original hypotheses are reevaluated or never be proven true (Morgan & Carter, 2011). As refined so that they can be retested, repeatedly, by should be obvious, a conflict potentially exists bet- the original researchers or by others. The process of ween the outcomes available to a scientist using the experimental testing, if done well, should lead to scientific method and those desired by officials new, more narrowly focused explanations of the working in a judicial system. original phenomenon that can be retested over and 3. Testing hypotheses. Hypotheses are tested through over. The idea is that with each subsequent round carefully controlled experiments. In this case, of experimentation, the scientist is moving closer ­controlled means that all possible variables or and closer to the real explanation, or in the case of factors that could influence the outcome of the criminal investigation, a step closer to the truth. experiment must be taken into consideration so that only one of them – the one being tested in the It is important to understand that the scientific method hypothesis – is allowed to vary during the study. is not simply a cookbook approach to scientific inquiry, The others are held as constant or static as possible meaning that once the final step is complete, the for the experimental conditions. For example, in a answer is known. Rather, doing science is a process study interested in testing the influence of tempera- whereby each observation leads to new questions with ture on the rate of development of necrophagous new hypotheses. The journey may seem endless, and fly larvae, the hypothesis will be based on the idea in the sense of new observations stimulating new ideas that temperature is the most important factor and new questions, it is. However, this systematic ­influencing development. In this example, temper- approach to addressing questions also guides us closer ature is the independent variable. Aspects of fly to the real answers and away from incorrect or false development that can be measured as impacted by explanations. temperature are called dependent variables, and It is also important to understand that the scientific might include overall length of development or method is not the sole source of information used by the duration of each stage of larval development. forensic entomologists and other scientists. Much of Other factors (e.g., food, , species of our understanding of the relationships between insects fly, size of maggot mass) which could potentially and decomposing carrion has come from publications be independent variables that influence fly relying on careful systematic observations rather than development must be maintained at a constant controlled experiments where a single variable is value (as much as is possible) and are referred to as manipulated to establish cause and effect. For example, Chapter 1 Role of forensic science in criminal investigations 7 we might be interested in knowing what insects are collected at the time the crime is discovered; we cannot associated with the early decay process of several go back a month later to get additional specimens to species of wildlife (Watson & Carlton, 2005) or what use as evidence. Empty puparia associated with a shal- species are attracted to human remains in a geograph­ low grave at the time of a body’s discovery are much ical area (Carvalho et al., 2000). These studies generate more relevant than empty puparia collected 2 months new data for forensic inquiry through system­atic obser- later at the old crime scene. In order to estimate PMI vations rather than by testing a clearly stated hypothesis. on a fairly fresh corpse, the entomologist needs to see The basic research that we compare against to establish the biggest maggots of as many different species as pos- postmortem interval (PMI) is based on detailed obser- sible to make the determination. Just ­collecting a few vations of a species life stage and size at different times ­maggots from the first larval mass encountered could and temperatures (Byrd & Butler, 1998). seriously compromise the ability of an ­entomologist to accurately estimate the time of death.

1.2.4 Analysis of physical evidence 1.2.4.2 Classification Physical or trace evidence collected from a crime scene Once an item has been recognized as physical is typically delivered to a crime laboratory or sent ­evidence, the object is processed in an attempt to identify directly to a forensic expert for further analyses. The it. Broadly, this means classifying the evidential object initial characterization may be simply a quantitative or into groups or categories. Hairs, bloodstains, and other qualitative assessment of the evidence (Jackson & body fluids must be identified to determine if in fact they Jackson, 2008). In other words, the analyses may be are human and, if not, to classify what animal or organism needed to determine the identity of the evidential the samples may have been derived from. For example, sample (qualitative analysis) in order to determine if a fly spots created by adult flies regurgitating undigested crime has even been committed, such as drug food (such as blood) onto a surface appear almost identification. In other instances, quantitative analysis ­indistinguishable from some types of blood spatter at is performed to determine the amount of a particular a crime scene (Parker et al., 2010). So an initial analysis substance that has been discovered in order to affirm of the spots is needed to classify them as either a blood- whether legal limits have been exceeded. Both forms of stain or some other object like an insect artifact. Likewise, analysis are relevant to entomological evidence. paint chips, powders, and other materials must be In the majority of cases, the forensic scientist evalu- ­identified so that objects can be grouped with similar ates physical evidence through comparison testing: the items. Comparisons are generally performed between evidential object may be compared to known objects the object of interest and known databases, reference in databases or validated reference collections such as ­collections or other validated resources. In the case of voucher specimens, or compared with the outcomes insects, voucher specimens are used to confirm relation- of controlled experiments. There are several ways in ships with an insect group (usually a family or genus). which comparison testing is utilized in forensic ­science The process of classification can also lead to the and the most common are discussed briefly here. exclusion of objects from a grouping. Such is the case with material such as paint chips, fibers or glass frag- ments, which may be broadly classified or grouped but 1.2.4.1 Recognition of evidence determined to be not the same as those found on a Recognizing whether a physical object is actually evi- victim, perpetrator and/or at some other location of dence is the first step in forensic analysis (Gaensslen interest. The object would be excluded or considered et al., 2007). Such determinations often rely on the dissociated from the crime scene since it does not experience of the forensic investigator or scientist, belong to the same class or group of interest. whereby the object has been previously observed dur- ing training, prior cases or experimentation. 1.2.4.3 Individualization When entomological evidence is present at a crime scene, care must be taken to collect as much material The process of classification leads to the identification as possible, even if much of the material will never be of the object so that it can be grouped or classified. used. In general, entomological evidence needs to be Classification is not intended to identify specifically 8 The science of forensic entomology

Outcomes of forensic analyses

Recognition of evidence Classification Individualization Reconstruction

Physical evidence Class identification Person identification, Explanation of events & & common origin, or through hypothesis trace evidence grouping of evidence uniqueness testing Figure 1.6 Types of comparison testing used in forensic analyses and the possible outcomes that can result. say the individual or, in the case of insects, exonerated because the or DNA do not the species of fly or beetle found on a corpse. Individ­ match those found at the crime scene or on the victim. ualization is a further level of identification, or ­narrowing of classification, that involves comparison 1.2.4.4 Reconstruction testing to ­distinguish an object as being unlike or unique from others in a grouping, or to determine The investigative efforts of a forensic scientist that per- that the physical evidence has the same source or haps most closely showcases use of the scientific origin when ­compared with another item in the same method is reconstruction. Because the process of class (Gaensslen et al., 2007). The latter is commonly reconstruction involves using the physical evidence done when impressions of shoe prints or tire tread and results from analyzing evidential objects to try to marks from a crime scene (scene impressions) are piece together the events of the crime, it can be thought ­compared with test impressions (Figure 1.6). The of as analogous to hypothesis testing. Crime scene impressions can then be identified further by mak- reconstruction requires formulation of explanations to ing ­comparisons with specific brand characteristics account for the evidence collected, testing the explana- using ­databases supplied with information from the tions and then, based on the test results, refining the manufacturers. initial hypotheses so that further testing can be per- The identity of a victim or an attacker like a rapist formed. The results of reconstruction can shed light can be determined or individualized through the use on the events that occurred before, during, or immedi- of DNA profiling on blood, semen or other body fluid ately after the crime was committed. This information evidence, or from analyses. In the case of is useful in corroborating or refuting statements an individual with a prior criminal record, the DNA made by a victim, suspect or eyewitness. As with sequences or fingerprints can then be compared in scientific inquiry, this form of forensic analysis yields databases like CODIS. Insect evidence can be identi- information that is mostly speculative theory based fied in a similar fashion by using a series of dichotomous predominantly on physical evidence. Reconstruction identification keys, voucher specimens, and even DNA does not “prove” anything is true (Figure 1.7). analysis to determine which species was collected from a crime scene. These testing procedures can lead to 1.2.4.5 Intelligence information positive identification of a victim, criminal and/or specimen. As with classification, individualization Ordinarily, gathering of intelligence information comparisons can also yield negative identifications or related to the activities of criminals falls outside the exclusions, for example an alleged suspect may be realm of the natural sciences, and is more consistent Chapter 1 Role of forensic science in criminal investigations 9

Observations Develop The remaining chapters focus exclusively on forensic lead to hypotheses ­entomology. Eleven major subdivisions of forensic questions ­science are recognized by the American Academy of Forensic Sciences (http://aafs.org, see Table 1.1), consid- ered to be the largest organization of forensic scientists in the world, with as many as 31 subdisciplines contrib- uting expert analyses in legal cases. Here we provide a Refine Evaluate Test hypotheses data hypotheses brief snapshot of some of the related fields of forensic science, and forensic entomologists may collaborate Figure 1.7 Schematic depiction of how the scientific with workers in these fields while working on a case. method is used in the process of scientific inquiry. 1.3.1 with disciplines focused on profiling. However, changes in the global interactions between different Synonymous with forensic medicine, forensic pathology groups of people, namely the widespread acts of is the discipline concerned with determining the cause ­terrorism, have broadened the scope of forensic sci- of death through examination of a corpse. A forensic ence. Terrorist acts have become very sophisticated as pathologist determines the medical reason for the has the “war on terror” employed by some nations. In ­person’s death and also attempts to decipher the the United States, several forensic scientists work to ­circumstances surrounding the death. The pathologist gather information on terrorist groups or cells by performs an autopsy at the request of the medical analyzing the weapons or components used to make examiner (a physician by training) or coroner (an elected the devices so that material suppliers or locations can official who may or may not be trained in medicine). be determined. Even insects have been used, as necrophagous fly larvae can be tested for bomb or other explosives residues in the hope that those 1.3.2 responsible can be identified and/or the location of explosives assembly, and hence the terrorist group, Forensic anthropology uses applied principles of can be identified. This approach relies on the assump- physical anthropology, the study of human form via tion that a terrorist cell or group has an established the skeleton system and osteology (study of bones) modus operandi, i.e., that they use characteristic to examine human remains in a legal context. explosive materials. Reconstructing a body from skeletal remains or making The preceding simply provides an overview of some individual or gender identifications are some of the main of the activities performed by forensic scientists. A functions of a forensic anthropologist. The “body more in-depth presentation of the roles of forensic farm” at the University of Tennessee in Knoxville is a ­scientists in forensic science and criminalistics can major research facility maintained by the Department be found in National Research Council Committee of Anthropology that essentially thrust forensic on Identifying the Needs of the Forensic Science anthropology into the limelight. The facility has been Community (2009) and Daeid (2010). instrumental in conducting basic and applied research using human corpses to shed light on factors influencing 1.3 Recognized decomposition and altering remains postmortem. specialty disciplines 1.3.3 Forensic in forensic science (odontology)

Forensic investigation is used to examine issues is the area of forensic science common to criminal, civil, and administrative matters. concerned with dentition or teeth as it pertains to legal To address such a vast array of topics, experts from matters. The discipline can essentially be divided into many disciplines are needed to perform forensic analyses. activities where dental patterns or individual teeth are 10 The science of forensic entomology used for identification of an individual or to whom information found on digital media and associated an individual tooth belongs, and use of bite marks devices as it pertains to civil and criminal matters. to ­individualize a potential attacker in which a victim has been bitten. Teeth can also be used as a source of DNA for subsequent identification as well. 1.3.7 Forensic botany

Forensic botany is the application of plant science 1.3.4 Forensic psychology to legal matters. Identification of plant species and psychiatry and application of plant development can be used to determine if a crime has been committed in a Forensic psychologists and forensic psychiatrists particular location, a body has been moved before or have similar roles in the judicial system. In some after death, and can help to calculate a portion of the instances, they determine if a defendant is competent PMI. In many ways, the roles of a forensic botanist to stand trial for the accused offense. In other are similar to those of a forensic entomologist. instances, the expertise of a psychologist or psychia- trist is needed in intelligence gathering, i.e., trying to characterize the patterns or other features of Chapter review the modus operandi of a criminal in an effort to ­apprehend the individual before he or she commits What is forensic science? another crime. This role is generally referred to as . •• Forensic science can be defined broadly as the use of scientific knowledge and technologies in civil and criminal matters, including case resolution, 1.3.5 enforcement of laws, and national security. •• Criminalistics is a term used to describe the Forensic toxicology primarily functions to analyze functions of a crime or forensic laboratory and repre- samples associated with poisoning, drug use, or death. sents a more narrow definition of forensic science.­ Forensic analyses performed by a forensic toxicologist •• The real value of science in legal matters is that it include qualitative analysis and classification to deter- relies on validation via scientific inquiry using the mine what the substance is, as well as quantitative scientific method, an approach that requires adher- analysis to determine amounts of substance. The latter ence to defined unbiased approaches to designing, can be significant in determining if a crime has been conducting and interpreting experiments. committed, such as when alcohol has been consumed, •• Public opinion of what forensic science is and what or deciphering causation of death when poisoning or it can do with regard to legal matters is riddled with an overdose is suspected. unrealistic expectations, termed the CSI effect from popular television crime shows like CSI: Crime Scene Investigation. 1.3.6 Computer forensic science/ Application of science This discipline is considered a branch of digital forensic to criminal investigations science and is focused on the information or data found on computer devices and other forms of digital •• Forensic science is used to investigate several issues media. As one might expect, the recent explosion of associated with criminal, civil, and administrative electronic data devices such as smart phones, MP3 matters. Most forensic scientists work on cases of a players, readers and all forms of laptop computers has civil or administrative nature, or deal with issues created an upsurge in training associated with digital related to national security such as those under the media. Computer forensic science focuses on the umbrella of the Department of Homeland Security identification, retrieval, preservation and storage of in the United States.