Explaining Forensics

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1 Introduction

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Learning Objectives

After studying this chapter, you should be able to:

Distinguish between forensic science and criminalistics.

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Outline the main historical developments of forensic science.
Describe the organization and services of a typical comprehensive
crime laboratory in the criminal justice system.
Understand what specialized forensic services, aside from the crime
laboratory, are generally available to law enforcement personnel.
Explain how physical evidence is analyzed and presented in the
courtroom by the forensic scientist, and how admissibility of evidence
is determined in the courtroom.

Casey Anthony: The Csi Effect?

Few criminal proceedings have captured the attention of the American
public or have invoked stronger emotions than the Casey Anthony murder
trial. How could a defendant who failed to report her two-year-old child
missing for thirty-one days walk away scot-free from a murder conviction?
This case had all the makings of a strong circumstantial case for the state.

The state’s theory was that Casey used chloroform to render her daughter
unconscious, placed duct tape over Caylee’s mouth and nose, and kept the
body in the trunk for several days before disposing of it. Caylee’s
decomposed remains were discovered more than five months after she
was reported missing.

Have TV forensic dramas created an environment in the courtroom that
necessitates the existence of physical evidence to directly link a defendant
to a crime scene? The closest the state came to a direct link was a hair
found in the trunk of Casey’s car. However, the DNA test on the hair could
link the hair only to Caylee’s maternal relatives: Casey, Casey’s mother
(Caylee’s maternal grandmother), and Casey’s brother (Caylee’s uncle). And
Caylee herself. No unique characteristics were found to link the duct tape
on the body with that found in the Anthony home.

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No DNA, no fingerprints, no conviction.

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for this chapter.

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Definition and Scope of
Forensic Science
Forensic science, in its broadest definition, is the application of science to
law. As our society has grown more complex, it has become more
dependent on rules of law to regulate the activities of its members.
Forensic science applies the knowledge and technology of science to the
definition and enforcement of such laws.

Each year, as government finds it increasingly necessary to regulate the
activities that most intimately influence our daily lives, science merges
more closely with civil and criminal law. Consider, for example, the laws
and agencies that regulate the quality of our food, the nature and potency
of drugs, the extent of automobile emissions, the kind of fuel oil we burn,
the purity of our drinking water, and the pesticides we use on our crops and
plants. It would be difficult to conceive of a food or drug regulation or
environmental protection act that could be effectively monitored and
enforced without the assistance of scientific technology and the skill of the
scientific community.

s are continually being broadened and revised to counter the alarming
increase in crime rates. In response to public concern, law enforcement
agencies have expanded their patrol and investigative functions, hoping to
stem the rising tide of crime. At the same time, they are looking more to
the scientific community for advice and technical support for their efforts.

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Can the technology that put astronauts on the moon, split the atom, and
eradicated most dreaded diseases be enlisted in this critical battle?

Unfortunately, science cannot offer final and authoritative solutions to
problems that stem from a maze of social and psychological factors.
However, as the content of this book attests, science occupies an
important and unique role in the criminal justice system—a role that relates
to the scientist’s ability to supply accurate and objective information about
the events that have occurred at a crime scene. A good deal of work
remains to be done if the full potential of science as applied to criminal
investigations is to be realized.

Because of the vast array of civil and criminal laws that regulate society,
forensic science, in its broadest sense, has become so comprehensive a
subject that a meaningful introductory textbook treating its role and
techniques would be difficult to create and probably overwhelming to read.
For this reason, we have narrowed the scope of the subject according to
the most common definition: Forensic science is the application of
science to the criminal and civil laws that are enforced by police agencies
in a criminal justice system. “Forensic science” is an umbrella term
encompassing a myriad of professions that use their skills to aid law
enforcement officials in conducting their investigations.

The diversity of professions practicing forensic science is illustrated by the
eleven sections of the American Academy of Forensic Sciences, the largest
forensic science organization in the world:

1. Criminalistics
2. Digital and Multimedia Sciences
3. Engineering Science
4. General
5. Jurisprudence

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�. Odontology
7. Pathology/Biology
�. Physical Anthropology
9. Psychiatry/Behavioral Science

10. Questioned Documents
11. Toxicology

Even this list of professions is not exclusive. It does not encompass skills
such as fingerprint examination, firearm and tool mark examination, and
photography.

Obviously, to author a book covering all of the major activities of forensic
science as they apply to the enforcement of criminal and civil laws by
police agencies would be a major undertaking. Thus, this book will further
restrict itself to discussions of the subjects of chemistry, biology, physics,
geology, and computer technology, which are useful for determining the
evidential value of crime-scene and related evidence. Forensic pathology,
psychology, anthropology, and odontology also encompass important and
relevant areas of knowledge and practice in law enforcement, each being
an integral part of the total forensic science service that is provided to any
up-to-date criminal justice system. However, these subjects go beyond the
intended scope of this book, and except for brief discussions, along with
pointing the reader to relevant websites, the reader is referred elsewhere for
discussions of their applications and techniques. Instead, this book
focuses on the services of what has popularly become known as the crime
laboratory, where the principles and techniques of the physical and natural
sciences are practiced and applied to the analysis of crime-scene
evidence.

For many, the term “criminalistics” seems more descriptive than “forensic
science” for describing the services of a crime laboratory. Regardless of
his or her title—“criminalist” or “forensic scientist”—the trend of events has

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made the scientist in the crime laboratory an active participant in the
criminal justice system.

The CSI Effect

Prime-time television shows like CSI: Crime Scene Investigation have
greatly increased the public’s awareness of the use of science in criminal
and civil investigations (see Figure 1-1 ). However, by simplifying
scientific procedures to fit the allotted airtime, these shows have created
within both the public and the legal community, unrealistic expectations of
forensic science. In these shows, members of the CSI team collect
evidence at the crime scene, process all evidence, question witnesses,
interrogate suspects, carry out search warrants, and testify in court. In the
real world, these tasks are almost always delegated to different people in
different parts of the criminal justice system. Procedures that in reality
could take days, weeks, months, or years appear on these shows to take
mere minutes. This false image is significantly responsible for the public’s
high interest in and expectations for DNA evidence.

Figure 1-1

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A scene from CSI, a forensic science television show.
SUN/Newscom

The dramatization of forensic science on television has led the public to
believe that every crime scene will yield forensic evidence, and it produces
unrealistic expectations that a prosecutor’s case should always be
bolstered and supported by forensic evidence. This phenomenon is known
as the “CSI effect.” Some jurists believe that this phenomenon ultimately
detracts from the search for truth and justice in the courtroom.

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History and Development of
Forensic Science
Forensic science owes its origins, first, to the individuals who developed
the principles and techniques needed to identify or compare physical
evidence and, second, to those who recognized the need to merge these
principles into a coherent discipline that could be practically applied to a
criminal justice system.

The roots of forensic science reach back many centuries, and history
records a number of instances in which individuals closely observed
evidence and applied basic scientific principles to solve crimes. Not until
relatively recently, however, did forensic science take on the more careful
and systematic approach that characterizes the modern discipline.

Early Developments

One of the earliest records of applying forensics to solve criminal cases
comes from third-century China. A manuscript titled Yi Yu Ji (“A Collection
of Criminal Cases”) reports how a coroner solved a case in which a woman
was suspected of murdering her husband and burning the body, claiming
that he died in an accidental fire. Noticing that the husband’s corpse had no
ashes in its mouth, the coroner performed an experiment to test the

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woman’s story. He burned two pigs—one alive and one dead—and then
checked for ashes inside the mouth of each. He found ashes in the mouth
of the pig that was alive before it was burned, but none in the mouth of the
pig that was dead beforehand. The coroner thus concluded that the
husband, too, was dead before his body was burned. Confronted with this
evidence, the woman admitted her guilt. The Chinese were also among the
first to recognize the potential of fingerprints as a means of identification.

Although cases such as that of the Chinese coroner are noteworthy, this
kind of scientific approach to criminal investigation was for many years the
exception rather than the rule. Limited knowledge of anatomy and
pathology hampered the development of forensic science until the late
seventeenth and early eighteenth centuries. For example, the first recorded
notes about fingerprint characteristics were prepared in 1686 by Marcello
Malpighi, a professor of anatomy at the University of Bologna in Italy.
Malpighi, however, did not acknowledge the value of fingerprints as a
method of identification. The first scientific paper about the nature of
fingerprints did not appear until more than a century later, but it also did not
recognize their potential as a form of identification.

Initial Scientific Advances

As physicians gained a greater understanding of the workings of the body,
the first scientific treatises on forensic science began to appear, such as
the 1798 work “A Treatise on Forensic Medicine and Public Health” by the
French physician François-Emanuel Fodéré. Breakthroughs in chemistry at
this time also helped forensic science take significant strides forward. In
1775, the Swedish chemist Carl Wilhelm Scheele devised the first
successful test for detecting the poison arsenic in corpses. By 1806, the
German chemist Valentin Ross had discovered a more precise method for

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detecting small amounts of arsenic in the walls of a victim’s stomach. The
most significant early figure in this area was Mathieu Orfila (see Figure 1-
2 ), a Spaniard who is considered the father of forensic toxicology. In
1814, Orfila published the first scientific treatise on the detection of
poisons and their effects on animals. This treatise established forensic
toxicology as a legitimate scientific endeavor.

Figure 1-2

Mathieu Orfila.
Matthieu Orfila/The Granger Collection

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The mid-1800s saw a spate of advances in several scientific disciplines
that furthered the field of forensic science. In 1828, William Nichol invented
the polarizing microscope. Eleven years later, Henri-Louis Bayard
formulated the first procedures for microscopic detection of sperm. Other
developments during this time included the first microcrystalline test for
hemoglobin (1853) and the first presumptive test for blood (1863). Such
tests soon found practical applications in criminal trials. Toxicological
evidence at trial was first used in 1839, when a Scottish chemist named
James Marsh testified that he had detected arsenic in a victim’s body.
During the 1850s and 1860s, the new science of photography was also
used in forensics to record images of prisoners and crime scenes.

Late-Nineteenth-Century Progress

By the late nineteenth century, public officials were beginning to apply
knowledge from virtually all scientific disciplines to the study of crime.
Anthropology and morphology (the study of the structure of living
organisms) were applied to the first system of personal identification,
devised by the French scientist Alphonse Bertillon in 1879. Bertillon’s
system, which he dubbed “anthropometry,” was a procedure that involved
taking a series of bodily measurements as a means of distinguishing one
individual from another (see Figure 1-3 ). For nearly two decades, this
system was considered the most accurate method of personal
identification. Bertillon’s early efforts earned him the distinction of being
known as the “father of criminal identification.”

Figure 1-3

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Bertillon’s system of bodily measurements used for the identification of an
individual.
Sirchie Finger Print Laboratories, Youngsville, NC, www.sirchie.com

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The Advent of Fingerprinting

Bertillon’s anthropometry, however, would soon be supplanted by a more
reliable method of identification: fingerprinting. Two years before the
publication of Bertillon’s system, U.S. microscopist Thomas Taylor had
suggested that fingerprints could be used as a means of identification, but
his ideas were not immediately followed up. Three years later, the Scottish
physician Henry Faulds made a similar assertion in a paper published in
the journal Nature. However, it was the Englishman Francis Henry Galton
who undertook the first definitive study of fingerprints and developed a
methodology of classifying them for filing. In 1892, Galton published a
book titled Finger Prints that contained the first statistical proof supporting
the uniqueness of fingerprints and the effectiveness of his method. His
book went on to describe the basic principles that would form our present
system of identification by fingerprints.

The first treatise describing the application of scientific disciplines to the
field of criminal investigation was written by Hans Gross in 1893. Gross, a
public prosecutor and judge in Graz, Austria, spent many years studying
and developing principles of criminal investigation. In his classic book
Handbuch für Untersuchungsrichter als System der Kriminalistik (later
published in English under the title Criminal Investigation), he detailed the
assistance that investigators could expect from the fields of microscopy,
chemistry, physics, mineralogy, zoology, botany, anthropometry, and
fingerprinting. He later introduced the forensic journal Archiv für Kriminal
Anthropologie und Kriminalistik, which still reports improved methods of
scientific crime detection.

Ironically, the best-known figure in nineteenth-century forensics is not a real
person but a fictional character: the legendary detective Sherlock Holmes
(see Figure 1-4 ). Many people today believe that Holmes’s creator, Sir

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Arthur Conan Doyle, had a considerable influence on popularizing scientific
crime-detection methods. In adventures with his partner and biographer, Dr.
John Watson, Holmes was the first to apply the newly developing
principles of serology (the study of blood and bodily fluids), fingerprinting,
firearms identification, and questioned-document examination long before
their value was recognized and accepted by real-life criminal investigators.
Holmes’s feats excited the imagination of an emerging generation of
forensic scientists and criminal investigators. Even in the first Sherlock
Holmes novel, A Study in Scarlet, published in 1887, we find examples of
Doyle’s uncanny ability to describe scientific methods of detection years
before they were actually discovered and implemented. For instance, here
Holmes explains the potential usefulness of forensic serology to criminal
investigation:

Figure 1-4

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Sir Arthur Conan Doyle’s legendary detective Sherlock Holmes applied many
of the principles of modern forensic science long before they were adopted
widely by real-life police.
Ostill/Shutterstock

“I’ve found it. I’ve found it,” he shouted to my companion, running toward us with a
test tube in his hand. “I have found a reagent which is precipitated by hemoglobin
and by nothing else… . Why, man, it is the most practical medico-legal discovery for
years. Don’t you see that it gives us an infallible test for bloodstains?… The old
guaiacum test was very clumsy and uncertain. So is the microscopic examination
for blood corpuscles. The latter is valueless if the stains are a few hours old. Now,
this appears to act as well whether the blood is old or new. Had this test been
invented, there are hundreds of men now walking the earth who would long ago

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have paid the penalty of their crimes… . Criminal cases are continually hinging
upon that one point. A man is suspected of a crime months perhaps after it has
been committed. His linen or clothes are examined and brownish stains
discovered upon them. Are they bloodstains, or rust stains, or fruit stains, or what
are they? That is a question which has puzzled many an expert, and why? Because
there was no reliable test. Now we have the Sherlock Holmes test, and there will
no longer be any difficulty.”

Twentieth-Century Breakthroughs

The pace of technological change quickened considerably in the twentieth
century, and with it the rate of advancements in forensic science. In 1901,
Dr. Karl Landsteiner discovered that blood can be grouped into different
categories, now recognized as the blood types A, B, AB, and O. The
possibility that blood grouping could be useful in identifying an individual
intrigued Dr. Leone Lattes, a professor at the Institute of Forensic Medicine
at the University of Turin in Italy. In 1915, Lattes devised a relatively simple
procedure for determining the blood group of the dried blood in a
bloodstain, a technique that he immediately applied to criminal
investigations.

At around the same time, Albert S. Osborn was conducting pioneering work
in document examination. In 1910, Osborn wrote the first significant text in
this field, Questioned Documents. This book is still a primary reference for
document examiners. Osborn’s development of fundamental principles of
document examination was responsible for the acceptance of documents
as scientific evidence by the courts.

One of the most important contributors to the field in the early twentieth
century was the Frenchman Edmond Locard (see Figure 1-5 ). Although

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Hans Gross was a pioneering advocate for the use of the scientific method
in criminal investigations, Locard first demonstrated how the principles
enunciated by Gross could be incorporated within a workable crime
laboratory. Locard’s formal education was in both medicine and law. In
1910, he persuaded the Lyons Police Department to give him two attic
rooms and two assistants to start a police laboratory. During Locard’s first
years of work, the instruments available to him were a microscope and a
rudimentary spectrometer. However, his enthusiasm quickly overcame the
technical and budgetary deficiencies he encountered, and from these
modest beginnings, Locard conducted research and made discoveries that
became known throughout the world by forensic scientists and criminal
investigators. Eventually he became the founder and director of the Institute
of Criminalistics at the University of Lyons, which quickly developed into a
leading international center for study and research in forensic science.

Figure 1-5

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Edmond Locard.
Roger Viollet/The Image Works

Locard asserted that when two objects come into contact with each other a
cross-transfer of materials occurs (Locard’s exchange principle ). He
strongly believed that every criminal can be connected to a crime by dust
particles carried from the crime scene. This concept was reinforced by a
series of successful and well-publicized investigations. In one case,
presented with counterfeit coins and the names of three suspects, Locard
urged the police to bring the suspects’ clothing to his laboratory. On careful
examination, he located small metallic particles in all the garments.
Chemical analysis revealed that the particles and coins were composed of
exactly the same metallic elements. Confronted with this evidence, the
suspects were arrested and soon confessed to the crime. After World War

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I, Locard’s successes inspired the formation of police laboratories in
Vienna, Berlin, Sweden, Finland, and Holland.

The Rise of the Microscope

The microscope came into widespread use in forensic science during the
twentieth century, and its applications grew dramatically. Perhaps the
leading figure in the field of microscopy was Dr. Walter C. McCrone. During
his lifetime, McCrone became the world’s preeminent microscopist.
Through his books, journal publications, and research institute, he was a
tireless advocate for applying microscopy to analytical problems,
particularly forensic science cases. McCrone’s exceptional communication
skills made him a much-sought-after instructor, and he educated thousands
of forensic scientists throughout the world in the application of
microscopic techniques. Dr. McCrone used microscopy, often in
conjunction with other analytical methodologies, to examine evidence in
thousands of criminal and civil cases throughout his long and illustrious
career.

Another trailblazer in forensic applications of microscopy was U.S. Army
Colonel Calvin Goddard, who refined the techniques of firearms
examination by using the comparison microscope. Goddard’s work allows
investigators to determine whether a particular gun has fired a bullet by
comparing the bullet with another that is test-fired from the suspect’s
weapon. From the mid-1920s on, his expertise established the comparison
microscope as the indispensable tool of the modern firearms examiner.

Modern Scientific Advances

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Since the mid-twentieth century, a revolution in computer technology has
made possible a quantum leap forward in human knowledge. The resulting
explosion of scientific advances has had a dramatic impact on the field of
forensic science by introducing a wide array of sophisticated techniques
for analyzing evidence related to a crime. Procedures such as
chromatography, spectrophotometry, and electrophoresis (all discussed in
later chapters) allow the modern forensic scientist to determine with
astounding accuracy the identity of a substance and to connect even tiny
fragments of evidence to a particular person and place.

Undoubtedly the most significant modern advance in forensic science has
been the discovery and refinement of DNA typing in the late twentieth and
early twenty-first centuries. Sir Alec Jeffreys developed the first DNA
profiling test in 1984, and two years later he applied it for the first time to
solve a crime, identifying Colin Pitchfork as the murderer of two young
English girls. The same case also marked the first time DNA profiling
established the innocence of a criminal suspect. Made possible by
scientific breakthroughs in the 1950s and 1960s, DNA typing offers law
enforcement officials a powerful tool for establishing the precise identity of
a suspect, even when only a small amount of physical evidence is
available. Combined with the modern analytical tools mentioned earlier,
DNA typing has revolutionized the practice of forensic science (see Figure
1-6 ).

Figure 1-6

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Sir Alec Jeffreys.
Homer Sykes/Alamy

Another significant recent development in forensics is the establishment of
computerized databases to store information on physical evidence such as
fingerprints, markings on bullets and shell casings, and DNA. These
databases have proved to be invaluable, enabling law enforcement officials
to compare evidence found at crime scenes to thousands of pieces of
similar information. This has significantly reduced the time required to
analyze evidence and increased the accuracy of the work done by police
and forensic investigators.

Although this brief narrative is by no means a complete summary of
historical advances in forensics, it provides an idea of the progress that
has been made in the field by dedicated scientists and law enforcement
personnel. Even Sherlock Holmes probably couldn’t have imagined the

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extent to which science is applied in the service of criminal investigation
today.

Quick Review
Forensic science is the application of science to criminal and civil laws
that are enforced by police agencies in a criminal justice system.
The first system of personal identification was called “anthropometry.” It
distinguished one individual from another based on a series of bodily
measurements.
Forensic science owes its origins to individuals such as Bertillon,
Galton, Lattes, Goddard, Osborn, and Locard, who developed the
principles and techniques needed to identify and compare physical
evidence.
Locard’s exchange principle states that when two objects come into
contact with each other, a cross-transfer of materials occurs that can
connect a criminal suspect to his or her victim.

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History and Organization of
Crime Laboratories
The steady advance of forensic science technologies during the twentieth
century led to the establishment of the first facilities specifically dedicated
to forensic analysis of criminal evidence. These crime laboratories are now
the centers for both forensic investigation of ongoing criminal cases and
research into new techniques and procedures to aid investigators in the
future.

History of Crime Labs in the United
States

The oldest forensic laboratory in the United States is the Los Angeles
Police Department, created in 1923 by August Vollmer, a police chief from
Berkeley, California. In the 1930s, Vollmer headed the first U.S. university
institute for criminology and criminalistics at the University of California at
Berkeley. However, this institute lacked any official status in the university
until 1948, when a school of criminology was formed. The famous
criminalist Paul Kirk was selected to head the school’s criminalistics
department. Many graduates of this school have gone on to develop
forensic laboratories in other parts of the state and country.

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In 1932, the Federal Bureau of Investigation (FBI), under the directorship of
J. Edgar Hoover, organized a national laboratory that offered forensic
services to all law enforcement agencies in the country. During its
formative stages, Hoover consulted extensively with business executives,
manufacturers, and scientists, whose knowledge and experience guided the
new facility through its infancy. The FBI Laboratory is now the world’s
largest forensic laboratory, performing more than one million examinations
every year (see Figure 1-7 ). Its accomplishments have earned it
worldwide recognition, and its structure and organization have served …