Forensic Science

By Laura Pettler, PhD

In Wiley’s Encyclopedia of Criminal Justice

Word Count: 4886/5000 words

According to the American Academy of Forensic Sciences (AAFS) (2011), “the word forensic comes from the Latin word forensis: public; to the forum or public discussion; argumentative, rhetorical, belonging to debate or discussion” (para. 1). Today the term forensic is primarily defined in two ways (a) as a public discussion or debate or (b) pertaining to all sciences used for legal purposes specifically when evidence is presented and evaluated using different reliability standards than is normally used to evaluate most types of evidence in the civil and criminal justice systems (AAFS 2011: para. 1). In its broadest definition, it could be defined as “the application of science to law” (Saferstein 2007: p. 4). Forensic scientists work in scientific laboratories, crime laboratories, in the field, in medical facilities, and in the courtroom. It is most often forensic scientists work on a team within a multiagency response effort where local, state, and/or federal authorities are responsible for the evidence related to a specific crime or situation. Forensic scientists and forensic practitioners are primarily trained in chemistry, biology, physics, and other hard sciences, but most have specialized or technical knowledge of specific scientific disciplines, such as pathology, toxicology, anthropology, odontology, entomology, psychiatry, engineering, digital evidence, investigation, questioned documents, and other related disciplines that allow them to contribute valuable information to a team of criminal justice professionals in their respective areas of expertise.

Forensic science is used in several ways today. The one most commonly thought of is how forensic science is used to help identify suspects who could be involved crimes. In contrast, the role forensic science plays is equally as important when testing yields results that prove an individual is innocent of a crime as well. Civil proceedings use forensic science to help illustrate flaws in a road or building, for example, or to refute claims made by consumers or manufacturers on products bought and sold.

Numerous milestones dating back to ancient times significantly mark the history of forensic science. Roman lawyer Quintilian, demonstrated to the court that a blind man was framed for his mother’s murder by using bloody handprints found at the scene of her death (University of Maryland at Baltimore [UMBC], 2011). Like Quintilian, Hippocrates (460-355 B.C.), also believed in the value of forensic medicine intertwined with law and argued that legal issues could be resolved by using information gathered from the lethality of wounds on a human body (Tilstone Savage & Clark 2006: p. 3).

According to Saferstein (2007), during the late 1800s, the father of criminal identification, Alphonse Bertillon, developed the first criminal identification system called anthropometry using body measurements (Saferstein 2007: p. 6). Leone Lattes’ research on typing dried bloodstains lead to the immediate use of the blood types A, B, AB, and O, discovered by Dr. Karl Landsteiner in criminal investigations (Saferstein 2007: p. 6). Although his work was not pursued, microscopist, Thomas Taylor in 1877 studied ridge detail on fingertips and found that it could be used to uniquely identify individuals (UMBC 2011). Calvin Goddard’s along with Walter McCone made the microscope a central piece of forensic analysis when Goddard determined two bullets came from the same firearm by comparing them under a microscope.

Criminal Investigation, published in 1893 by Austrian prosecutor Hans Gross discussed the application of scientific principles to criminal investigation (Saferstein 2007). Gross argued that careful observation and the very nature of science, such as microscopy, chemistry, and physics could assist criminal investigators in criminal cases and explained what they might expect to discover using science in their investigations (Saferstein 2007). Gross promoted the Scientific Method, a five-step process, which tests hypotheses developed from relevant sources of data because he argued that it could be used to help determine events in criminal cases (Saferstein 2007). Although Gross was a staunch advocate for incorporating the scientific method into criminal investigation, Gross did not contribute to the philosophical or methodological aspects of its application specifically.

In the early 1900s, Victor Balthazard and Marcelle Lambert published the first hair study and Balthazard published findings on matching bullets to firearms using microscopes (UMBC 2011). According to Saferstein (2007), Edmund Locard started a laboratory in 1910 in two attic rooms with two assistants on behalf of the Lyons Police Department and demonstrated how Gross’s work could become an integral part of criminal investigation. As the founder of the Institute of Criminalistics at the University of Lyons, Locard studied numerous investigations that led him to develop the concept that every time two individuals come into contact with one another particles of material are exchanged between them (Chisum & Turvey 2000). “Locard’s Exchange Principle” was Locard’s greatest contribution to forensic science because it helped illustrate the importance of collecting physical evidence from crime scenes for the purpose of criminal identification and for determining the actions of criminals in a crime scene coupled with the need for technological advancement to analyze the cross-transfer of materials between a suspect and a victim (Chisum & Turvey 2000; Saferstein 2007: p. 9).

According to the International Association for Identification (IAI) (2011), twenty-two men formed the International Association for Criminal Identification (IACI) in October 1915 with Inspector Harry S. Caldwell as the presiding officer to further the goals of forensic identification. The IAI as its known today is the oldest and largest forensic association in the world (IAI, 2011). According to Saferstein (2007), Locard’s Exchange Principle propelled the United States Federal Bureau of Investigation (FBI) to create a crime laboratory in 1932. Interestingly, the FBI’s crime laboratory is not the United States oldest crime lab; Berkley, California Police Chief August Vollmer formed the oldest crime laboratory in the United States in the Los Angeles Police Department in 1923. Then, Vollmer collaborated with the University of California at Berkley in the 1930s to develop the United States’ first institute for criminology and criminalistics. World famous forensic scientist, Dr. Paul Leland Kirk, a four-runner in bloodstain pattern analysis and crime scene reconstruction was named head of the school of criminology when it was formed in 1948 affording Vollmer’s institute the opportunity to gain official status within the university. Kirk’s, Crime Investigation, published in 1953 signified another milestone in forensic science as the first comprehensive text that integrated criminal investigation practice with theory (UMBC 2011).

The admissibility of scientific evidence has long been a topic of the United States Criminal Justice System. The Court opined in Frye v. United States (1923) that expert witness may only present testimony developed from using scientific techniques that are generally accepted within the scientific community. The Frye Standard or Frye Test stemmed from an issue raised over the admissibility of information gleaned from polygraph examinations (Frye v. United States 1923). Later in Daubert v. Merrell Dow Pharmaceuticals, Inc. (1995) the United States Supreme Court handed down a ruling that superseded the Frye Standard, which stated that scientific evidence deemed admissible in court must meet several guidelines: the judge is the “gatekeeper” and must make sure the testimony is based on scientific knowledge and is relevant to the case; the scientific method is the foundational methodology of the testimony; and the methodology must be generally accepted in the scientific community. In 2000, Evidence Rule 702, or the Daubert Test, was condensed into the Daubert Trilogy by keeping the role of the gatekeeper and consolidating the general guidelines for the admissibility of scientific evidence (Herrero 2005).

According to DiMaio and DiMaio (2001) “forensic pathology is a branch of medicine that applies the principles and knowledge of the medical science to problems in the field of law” (p. 1). Forensic pathologists conduct autopsies to help determine causes of death, manners of death, and examine wounds typically involved in traumatic and unexpected deaths (Wright 2005). According to Wright (2005) the chain of events that results in a disease or injury becoming fatal can create a multitude of causes of death, while forensic pathologists only render four manners of death: accident, natural, homicide, and suicide. Forensic pathologists are also responsible for identifying the deceased, determining time of death when possible, collecting evidence from the body, and for documenting all injuries inflicted on victim. Forensic pathologists publish autopsy reports and often provide expert witness testimony of their findings in a court of law.

Mathieu Joseph Bonaventure Orfila (1787-1853), is known as the father of toxicology (Saferstein 2007). Orfila studied chemicals as they related to death and in 1812 published his first official work on the subject (National Library of Medicine 2006: para. 2). According to the Forensic Toxicology Council (the Scientific Working Group of Toxicologists) (2010), forensic toxicology “deals with the application of toxicology to cases and issues where those adverse effects have administrative or medicolegal consequences, and where the results are likely to be used in court” (p. 1). Forensic toxicology can be divided into four broad categories: death investigation toxicology or postmortem toxicology, human performance toxicology, doping control, and forensic workplace testing (p. 2). Death investigation forensic toxicologists help determine how drugs, poisons, and alcohol, for example, might have played an adverse role in the death of an individual, but human performance forensic toxicology is used from the medico-legal standpoint to assess the role drugs or alcohol might have played in human behavior during an incident. Doping control forensic toxicologists work with human and animal athletic associations to verify that all athletes are within the ethical and acceptable ranges of medical-legal drug use allowable by the respective sports they are participating in. Further, work place forensic toxicologists help control drug usage in the workplace because of the high-costs associated with drug abuse and risks to public safety. Forensic toxicologists use state of the art technology, such as screening test instrumentation called thin layer chromatography (TLC), gas chromatography (GC), and immunoassay to test biological samples (Saferstein 2007).

According to the American Board of Forensic Anthropology (2008), forensic anthropology is “the analysis of skeletal, badly decomposed, or otherwise unidentified human remains is important in both legal and humanitarian contexts” (para. 1). Forensic anthropologists aid criminal investigations by analyzing human remains using standard scientific techniques of physical anthropology to determine develop demographic information, such as ancestry, age, and sex to help identify victims of natural disasters, mass disasters, etc. According to Klepinger (2006), forensic anthropology stemmed from traditional twentieth-century physical anthropology and bioarcheology because anatomists and physicians historically relied on bones to help reveal biological and even cultural aspects of people. The value of the medico-legal aspects of bones in criminal investigations has always been recognized, but more recently, forensic anthropologists have become a centerpiece in forensic science for helping to determine the cause of death in some cases where little or no soft tissue might be present for analysis.

According to Glass (2005) “forensic odontology or forensic dentistry is the application of the arts and sciences of dentistry to the legal system” (p. 79). Forensic odontologists help identify human remains in mass disasters, such as hurricanes and airplane crashes, or sometimes when the skeletal remains recovered from a location that include teeth. Odontologists use unique aspects of human teeth, called dentition to compare to known standards. Using dentition as a means to verify or authenticate death can be traced back to the Claudius, the Roman Emperor verified his mistress’s death by examining her discolored tooth in her head. Odontologists are trained and licensed dentists who provide expert witness testimony in civil and criminal courts about dentition, bite marks, or in malpractice related cases.

The crime scene is the centerpiece from which most types of physical evidence are first secured, then systematically identified and documented in notes and chains of custody, photographed, video-taped, measured and sketched, along with numerous other processing methods and techniques, collected and preserved before they are taken to the crime laboratory for analysis (Gardner 2005; Geberth 2006; Robinson 2007; Saferstein 2007). Some credit Hans Gross with developing the term criminalistics (UMBC 2011) and according to the American Board of Criminalistics (2010), criminalists analyze physical evidence in the crime laboratory.

A crime laboratory can contain several different sections with capabilities of analyzing numerous types of evidence, such as bloodstain pattern evidence, latent evidence, fingerprint evidence, trace evidence, drug evidence, firearms and ballistic evidence, and tool mark and impression evidence. Criminalists are trained to perform various types of organic and inorganic chemical, biological, and physical tests using laboratory instrumentation, such as highly sophisticated microscopes, TLC, GC, liquid chromatography, and spectrometry to analyze evidence. Criminalists’ broad base of knowledge is critical to their role because a proper sequence of testing must be performed to maximize the opportunity for results. Using known standards secured from suspects, victims, and witnesses, criminalists compare and contrast data generated from testing evidence in the crime lab to help include, exclude, confirm, or refute matters relating to criminal cases. Criminalists are non-biased forensic scientists because they simply interpret the data and report the results, which is often presented as expert witness testimony in a criminal court.

The history of fingerprints can be traced back to ancient times. Carvings of human beings and paintings on rocks revealed the significance fingerprints had to ancient people in prehistoric times (UMBC 2011). During the 700s BC, the Chinese established identity using fingerprints although no formal fingerprint classification system existed at that time (UBMC, 2011). In 1880 a suspect from a Tokyo burglary was proven innocent by physician Henry Faulds using fingerprints, which led Faulds to publish an article in the journal Nature about how fingerprints could be used to identify suspects at crime scenes because additionally, Faulds used fingerprints to implicate the real Tokyo burglary culprit (UMBC 2011). The 1890s were an especially significant time period because Sir Francis Galton published Fingerprints, the first comprehensive book on how fingerprints are instrumental in solving crimes and Sir Edward Richard Henry developed the “Henry Classification System” that changed the way fingerprints were used in criminal investigations in Europe and North America forever (UMBC 2011). The Henry Classification System eventually replaced Bertillion’s anthropometry in 1901 when Sir Henry was named the head of Scotland Yard (UMBC 2011). Because the ridge detail in fingerprint ridge patterns: loop, whorls, and arches remain constant from birth, the year 1918 was a significant milestone in fingerprint history when Locard suggested that 12 matching points within a fingerprint pattern constituted a positive fingerprint match or identification (UMBC 2011; Saferstein 2007). As fingerprint research has continued throughout the twentieth and twenty-first centuries, the Automated Fingerprint Identification Systems (AFIS) that automated fingerprint identification was upgraded in1999 with the Integrated Automated Fingerprint Identification System (IAFIS), which centralized storage and created paperless submissions of the localized AFIS for broadband, nationwide search capabilities (Federal Bureau of Investigation 2011).

Biological evidence, such as blood is commonly recovered in violent criminal cases. During the 1950s, the several scientists diligently studied blood typing and how to identify individuals based on blood type alone (UMBC 2011). Until Sir Alec Jeffreys developed the first deoxyribonucleic acid (DNA) profiling test in 1985, fingerprint ridge patterns were used for decades along with the second half of the twentieth century technological advancements of blood-typing for criminal identification (UMBC 2011). Two young girls were murdered in 1986 and Jeffreys DNA test was used to exonerate an innocent suspect and convict Colin Pitchfork of their murders in the English Midlands (UMBC 2011). Jeffreys’ DNA analysis test focused on detecting a multilocus Restriction Friction Length Polymorphism (RFLP) pattern that was introduced in a United States criminal court in 1987, which subsequently was used to convict Tommy Lee Andrews in Orland, Florida of a series of sex offenses (UMBC 2011). According to Duncan, Martin, and Stauffer (2005) DNA analysis testing has evolved through several phases of technological testing advancements since the launch of the RFLP test in the 1980s. By the 1990s, polymerase chain reaction (PCR), which copied strands of DNA material made RFLP testing obsolete. Today short tandem repeat or STR DNA analysis is used worldwide in a variety of ways because STR analysis has overcome some of the biological degradation obstacles of the DNA itself that PCR and RFLP analysis could not.

Arboleda-Florez (2006) argued that forensic psychiatry had traditionally been narrowly defined to deal with issues directly surrounding psychiatry and the law (p. 87). Today fornesic psychiatry and behavioral science is applied more broadly throughout the criminal justice system by helping metally ill individuals involved in the legal system navigate the mental health, courts, and correctional systems (p. 87). Forensic psychiatrists and behavioral scientists conduct evaluations of mentally ill individuals for penal, criminal, and civil law purposes along with serving as an interface for mentally ill individually as they move along the continuum of the justice system. According to the American Academy of Forensic Sciences (2011), forensic psychiatrists play a key role in the criminal justice system by evaluating defendants comptency to stand trial, waive legal representation, or to be executed (para. 1). Forensic pyschiatrists also play a role in civil law when disability questions arise, involuntary psychiatric hospitalization, or the do-not resuscitate decisions need to be made (para. 1). Further, forensic psychiatry reaches into family and domestic courts by responding to juvenile delinquency issues, domestic violence, and child custody issues (para. 1).

According to the National Academy of Forensic Engineers (NAFE) (2009a) forensic engineering is “the application of the art and science of engineering in matters, which are in, or may possibly relate to, the jurisprudence system, inclusive of alternative dispute resolution” (para. 1). Forensic engineering can be divided into three broad categories: structural failures, basic fire and explosive investigations, and vehicular accident reconstruction (Redsicker 2005). However, within the three broadest categories most often seen in criminal cases, forensic engineering is vastly encompassing to include sub-disciplines of engineering, such as chemical, civil, computer, geological, mechanical, and safety (NAFE 2009b). According to Saferstein (2007) forensic engineers help determine if structures like houses, commercial buildings, or sports complexes were built properly when individuals are injured and companies are sued in civil court. Design failure, leaking roofs, and chemicals can all play a significant role in maintaining a building’s structural soundness, thus, it is the job of the forensic engineer to examine and analyze the potential risks of this nature might have caused when people are injured as a result of a failure. Forensic engineers who are responsible for investigating fires and explosions use the scientific method to help determine facts about each case and how chemicals might have behaved within those circumstances. Automobile fire, residential fire, commercial building fires, electrical fires, etc. are investigated using this method in a collaborative effort to establish what caused the fire, where it started, and other important facts related to the guilt or innocence of individuals involved in criminal cases. The third broad category of forensic engineering, vehicular accident reconstruction is a critical piece of forensic engineering work today. Because thousands of people are killed each year in motor vehicle related crashes, tremendous amounts of resources are dedicated to determining the causes, developing technology to analyze crashes, and learning how to use collected data to understand the sequence of events of an incident. Forensic engineers use the Conservation of Energy law, which deals with the way energy is dispersed, used, or how energy is expended before, during and after a vehicle crash.

According to the Forensic Sciences Foundation (2011), the advent of digital photography spurred the digital evidence and computer science aspects of forensic sciences into innovative technological advancements for criminal investigations. While the area of digital photography for the purpose of crime scene reconstruction or recreation requires a continual amount of empirical research, the criminal justice system has saved time and money by moving from traditional film photography systems to digital photography systems for crime scene documentation, autopsy documentation, vehicle crash documentation, and other areas of forensic science application. Forensic scientists ground their work in digital evidence analysis on scientific principles and typically examine and analyze evidence in digital forensic laboratories. Laboratories are equipped with specialized chemical, mechanical, and computerized hardware and software instrumentation and examiners conduct tests, such as comparisons of digital images, network analysis, and photogrammetry (para. 4). Examiners help investigators who work cases that might involve computer crimes against children, such as downloading child pornography, determining what websites were visited on a computer, or determining a timeline on a computer. Computer forensics is a critical component of criminal investigation today towards maintaining national security, state-level security, local security, and securing personal information within banking systems and on personal computer systems (American Academy of Forensic Sciences 2011).

As mentioned above, Albert Osborn developed the field of questioned document examination and the court’s acceptance of this type of evidence rests on Osborn’s tireless work (Saferstein 2007). In 1942, Osborn along with other well established questioned document practitioners formed the American Society of Questioned Document Examiners to promote education, research, and standards for their field (American Society of Questioned Document Examiners [ASQDE], 2011). According to the ASQDE (2011), questioned document examiners are more commonly known as forensic document examiners and work in federal, state or local crime laboratories, or are employed in the private sector and work primarily on civil cases (para. 1; para. 2.). Comparing the handwriting and signatures of a sample known to have been written by a suspect in a criminal case to a document that is recovered a crime scene for example, is the primary role of the forensic document examiner. Forensic document examiners help to determine whether an individual did or did not write a document in question and are often called into criminal court to testify on such matters. Several other types of examinations from various machines and other written or typed items are commonly performed by forensic document examiners, such as “typewriting, computer printed documents, photocopies, decipherment of altered, obliterated and charred documents, the examination of inks and paper, decipherment of erased entries and indented writings, detection of counterfeit currency, and the examination of commercially printed matter” (para. 2).

National Research Council of the National Academy of Sciences (2009) published a report entitled, Strengthening Forensic Science in the United States: A Path Forward. The “NAS Report” as it is commonly referred to among forensic practitioners in the field was a review of the overall health of forensic science in United States today. The NAS Report generated a series of recommendations to improve the quality of forensic science policy, practice, and quality control in the United States citing several critical issues including a paucity of empirical research that confirms the validity and reliability of techniques used in forensic science applications today in every discipline except DNA analysis. The American Academy of Forensic Sciences (2009) and the International Association for Identification (2009) among other specialized professional associations supported the NAS Report’s recommendations and are proactive in influencing administrators, legislators, practitioners, and others who play a key role in the development several areas in need of improvement, such as accreditation boards for law enforcement agencies, crime laboratories, forensic practitioner certification programs, Standard Operating Procedures (S.O.P.s) for crime scene processing and laboratory analysis, and forensic scientist discipline-specific proficiency testing.

SEE ALSO: Anthropology; Biology; Chemistry; Crime Scene Investigation; Crime Laboratory; Criminalistics; DNA; Digital Evidence; Entomology; Fingerprints; Forensic Pathology; Forensic Psychiatry; Odontology; Quality Control of Forensic Science; Toxicology.

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