The Science of Forensic Entomology

David B. Rivers, Gregory A. Dahlem

• Publisher: Wiley-Blackwell
• Year: 2013
• ISBN:
  9781118403037
• Edition: 1
• Topic: Medicina
• Subtopic: Medicina forense

The Science of Forensic Entomology builds a foundation of biological and entomological knowledge that equips the student to be able to understand and resolve questions concerning the presence of specific insects at a crime scene, in 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 insect biology that forms the bases 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 maggot masses, temperature tolerances of necrophagous insects; chemical attraction and communication; reproductive strategies of necrophagous flies; 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 arthropods in a wide range of legal matters.

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

Before an in-depth discussion of forensic entomology can really begin, there is a need to define the relationship between this discipline and the broader field of forensic science. As the name implies, science is the core of forensic analyses. It is only fitting, then, that Chapter 1 begins with an exploration of the application of science to legal matters, which also serves as a simple working definition of forensic science. Throughout the chapter, emphasis will be placed on the use of the scientific method in all forms of forensic analyses, from the process of analyzing physical evidence to understanding the types of outcomes associated with forensic analyses. The different specialty areas of forensic science will be discussed to allow a perspective of the broad impact of science on criminal and civil investigations.

The big picture

• What is forensic science?
• Application of science to criminal investigations.
• Recognized specialty disciplines in forensic ­science.

1.1 What is forensic science?

Science is used to solve crimes. In fact, it is ­instrumental in resolving cases involving both civil and criminal issues, particularly those of a violent nature. Not ­surprisingly, crime too has become more sophisticated, with today’s criminals relying on aspects of ­science to threaten individual and national security. One has to look no further than bioterrorism to see a clear linkage between scientific understanding and violent criminal activity. This chapter is devoted to understanding the relationship between science and criminal investigations. Particular attention is given to understanding the scientific method, a defined way of doing science, as it serves as the core principle for studying natural phenomena and in forensic analyses.

Forensic science has become a broad term, departing somewhat from the simple definition given earlier in which it was stated to be the application of science to law. The term “forensic” is defined as pertaining to or connected with the law, while “science” is the study of the physical and natural world through ­systematically arranged facts and principles that are rigorously tested by experimentation. When used together the two terms yield a discipline that addresses issues ­pertaining to or connected to the law through the application of tested facts and principles and by use of rigorous experimentation. As mentioned previously, the definition of forensic science has become more encompassing, now representing a vast array of medical, scientific (natural and applied) and social scientific disciplines (Table 1.1). So now we may revise our definition of forensic science to reflect modern, broader approaches: “the use of scientific knowledge and technologies in civil and criminal matters, including case resolution, enforcement of laws and national security.” The term criminalistics is commonly used to narrow this broader definition into the specific activities of a crime or forensic laboratory (Gaensslen et al., 2007). Most aspects of applying science to the law, including those associated with forensic entomology, fall under the umbrella of criminalistics.

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

Section	Membership totals*
Criminalistics	2571
Digital + Multimedia Sciences	90
Engineering Sciences	157
General	702
Jurisprudence	189
Odontology	429
Pathology/Biology	878
Physical Anthropology	423
Psychiatry/Behavioral Science	135
Questioned Documents	198
Toxicology	516

*Membership data as of July 8, 2011 at http://www.aafs.org/sections. Forensic entomologists typically belong to the Pathology/Biology section of AAFS.

Use of the term “forensics” as a substitute for “forensic” has confused the terminology to some degree. The former term originally meant the study or art of debate or argumentation. Hence, a school debate team practices forensics or debating. Though “debate” between attorneys has a defined role in the courtroom, it does mean pertaining to the law. However, within the court of public or popular opinion, “forensics” has come to imply forensic science. In fact, a word search on the internet or in some dictionaries yields results which indicate that “forensics” can also be defined as referring to the law. In today’s society, practice tends to set policy or norms and, as such, “forensics” is quickly becoming an accepted term for forensic science. No doubt this expanding definition has its origins with the popular television crime shows.

Figure 1.1A knife found at a crime scene is an example of physical evidence. Photo by Ricce. Image available in public domain at http://commons.wikimedia.org/wiki/File:Knife_Fox.webp

Yet another impact of the rising popularity of forensic science through television programming is the phenomenon known as the CSI effect (Saferstein, 2011). The name is derived from the very popular ­television series CSI: Crime Scene Investigation (airing on the CBS network). In general terms, the increased public attention to forensic science is usually linked to this TV series. However, there are numerous other influences that have contributed to the soaring popularity. Regardless of the source of influence, the public’s perception of what science can do for a criminal ­investigation has become distorted. Many individuals, including those who potentially serve as jurors, have become convinced from TV shows that when the experts (i.e., forensic scientists) are called in to ­investigate a crime, they will always find physical evidence and that detailed analyses in the crime lab, using real and imaginary technologies², will ultimately solve the crime by identifying the perpetrator (Figure 1.1). When delays occur during an investigation or when there is simply little or no evidence to go on, the victim(s), families and even jurors become frustrated and believe the problem is the incompetence of the investigative team. After all, it only takes 1 hour for the CSI team to examine the crime scene, find evidence, analyze it, identify suspects, interview the suspects, and seal a full confession! This impressive effort is usually achieved by only one or two people, who perform all the functions that in real life would normally require a team of individuals. Of course, in reality the process is much more time-consuming, requiring many individuals working together, and often a crime goes unsolved. When television fantasy is not separated from reality, the result is that unrealistic expectations are placed on law enforcement officials based on the public’s belief that television reflects the real world of forensic science and criminal investigations.

The reality is that the application of science to legal matters can profoundly influence the resolution of a crime. However, there are limitations to what can and cannot be done, some of which will be addressed later in this chapter. The real value of science in legal matters is that it relies on validation via scientific inquiry using the scientific method. The scientific method is the key, as its use requires adherence to defined ­unbiased approaches to designing, conducting, and interpreting experiments. Human emotions or desires, as well as error, are minimized so that the facts, or truths in the case of law, can come to light. A more detailed discussion of the scientific method can be found in section 1.2.3.

1.1 Application of science to criminal investigations

What can forensic science do to help in civil and criminal cases? Or more to the point, what do forensic scientists do? Forensic investigation is used to address numerous issues associated with criminal, civil and administrative matters. Indeed, most forensic scientists actually work on cases of a civil or administrative nature, or deal with issues related to national security such as those under the umbrella of the Department of Homeland Security in the United States (Gaensslen et al., 2007). The focus of this book is medicocriminal entomology, so the emphasis in this chapter is placed on criminal matters.

So how do forensic scientists contribute to criminal investigations? In section 1.1 we spent some time ­discussing what they cannot do: solve crimes as on CSI. In real cases, forensic scientists spend the majority of their time applying the principles and methodologies of their discipline to the elements of the crime. In other words, a great deal of time is devoted to using the scientific method. Interestingly, training in scientific inquiry is not a universal feature of the curricular ­pedagogy of all the disciplines contributing to forensic science. Graduates in traditional science subjects such as biology, chemistry and physics (collectively referred to as the natural sciences), and even geology, are trained in rigorous...