Forensics

SIGNIFICANCE: Forensic science and forensic medicine, as they relate to the processing of crime scene evidence, have become increasingly crucial to the resolution of cases within the criminal justice system, particularly as evolving technologies have allowed forensics to make ever greater contributions to criminal investigations.

Forensic science broadly encompasses the use of science in both criminal and civil courts. The types and variety of forensic evidence that can be presented in courtrooms are almost limitless. In criminal courts, forensic evidence is essential in drug cases. Forensic medicine is especially valuable in the handling of evidence relating to bodies in homicide and rape cases. In civil courts, forensic evidence is often presented in product-liability cases and injury cases.

Forensic Specialties

The field of forensic science includes a variety of subdisciplines. These include forensic medicine, forensic anthropology, forensic entomology, forensic odontology, forensic palynology, forensic serology, and criminalistics. Forensic medicine is further divided into the areas of forensic pathology, forensic toxicology, and forensic psychiatry.

Forensic pathology studies how and why people die and concentrates on sudden, unexpected, and violent deaths. During homicide investigations, forensic pathologists frequently perform autopsies. Forensic toxicology is concerned with chemicals—especially drugs and poisons—found in human bodies. During death investigations, forensic toxicologists may make determinations on whether victims have been killed by poisons, such as lead. Toxicology analyses can also be sued to determine whether a drug such as Rohypnol—the so-called “date-rape” drug—has been used in sexual assaults.

Forensic odontology, which is also known as forensic dentistry, deals with dental evidence. It is usually used to identify bodies or to link bite marks on victims to dental impressions of suspects. Forensic psychiatrists combine knowledge and practical experience in medicine, mental health, and the neurosciences and are called upon to testify in the courtroom regarding psychological disorders and disabilities.

Forensic anthropologists are most frequently called upon when human skeletal remains are found. Anthropologists use the remains to assist in identifying victims. They may also provide approximate dates and causes of death. Forensic entomology studies how insects colonize dead bodies. On the basis of examination of insects, estimates of times of death can be made. Forensic serologists specialize in identifying and processing blood, semen, saliva, and other bodily fluids. They may also be involved in analyses of bloodstains, blood spatters, and DNA specimens. Such evidence is often crucial in sexual assault cases and homicide investigations.

Criminalistics

Criminalistics is a broad area of forensics that is concerned with analyses of a wide variety of evidence. It encompasses questioned documents, voice examinations; ballistics and firearms; tool marks; fingerprints; tire-tracks and shoe prints; paint and glass fragments; hair, fibers, and soil; and arson and explosives. The area of questioned documents includes all types of possible forgeries of documents, papers, inks, computer copies, and handwriting analysis. Voice examination is employed to identify speakers and to ascertain whether speakers are telling the truth.

Ballistics is the study of the physics of objects in flight. In forensics, it is primarily concerned with bullets and other projectiles used as weapons. Ballistics experts can determine the angles at which projectiles strike surfaces and the damage that the projectiles cause.

Experts in firearms study all types of guns, shotguns, bullets, cartridges, and cases. Tool marks are most often found at the scenes of burglaries and other crimes at which criminals gain forcible entry into secured areas. Fingerprint experts dust for, lift, and analyze fingerprint evidence left at crime scenes. Tire-tracks and shoe prints, like fingerprints, are impressions that are often left at crime scenes and can be lifted or copied in castings made with plaster-like materials.

Many experts deal with fragment and fiber evidence and examine the microscopic differences in paints, glass, hairs, fibers, and soils. For example, through thorough examination, it may be possible to match minute samples from a crime scene with the paint or glass on a suspect’s car. Paint and glass examination are frequently important in the prosecution of hit-and-run cases.

Affiliated Fields

Areas related to forensic science include forensic psychology, forensic nursing, forensic accounting, forensic engineering, and forensic computer analysis. Forensic psychology includes such activities as criminal personality profiling, child custody evaluations, and litigation consultation. Forensic nursing is an emerging specialization within nursing that concentrates on working with victims of sexual assault and domestic violence. It also contributes to evidence collection for law enforcement.

Forensic accounting utilizes accounting principles to evaluate the financial paperwork of organizations to determine if fraud is present. This specialization within accounting has become increasingly important due to highly publicized increases in financial wrongdoing among large corporations. Forensic engineering studies how structures respond to stresses. Forensic engineers explained how and why the Twin Towers of the World Trade Center collapsed during the terrorist attacks of September 11, 2001. Forensic computer analysis is the specialty within computer science that deals with analyses of computer evidence for the prosecution of individuals who steal or alter computer data.

History of Forensic Science

There are two distinct historical threads within forensic science. The first is the history of the development of law enforcement and investigation techniques. The second is the history of a variety of scientific advances that have been useful to solve cases.

The techniques used by investigators and detectives to solve cases have traditionally been called criminalistics. Has Gross, who is credited as the founder of modern criminalistics, worked as a prosecutor and judge in Austria. He was responsible for publishing the first professional paper on the application of the sciences to criminal investigation during the 1890s.

Locard’s Exchange Principle, named for the French criminalist Edmond Locard, is the guiding principle behind all forensic science. It states that whenever two objects come into contact with each other, there is an exchange of materials between them. In other words, when crimes are committed and the offenders are at the crime scenes, the offenders invariably leave behind material—which may be microscopic—that can be traced back to them. Locard established an early crime laboratory in Lyons, France, in 1910.

Alphonse Bertillon developed the first system of person identification, based on body measurements, in Paris during the mid-nineteenth century. His system was soon replaced by fingerprints, which were found to be more individual than the body measurements.

The first forensic laboratory in the United States was opened by the Los Angeles Police Department during the early 1920s. During the 1930s, several state laboratories were set up throughout California. California’s early start in forensics gave it an edge in the field that it retained into the twenty-first century. Meanwhile, the United States Federal Bureau of Investigation established its first forensic laboratory in 1932.

Since the field of forensics was founded, it has been advanced by numerous scientific advances. These include developments in microscopy—from Galileo’s invention of the first microscope in the sixteenth century to the invention of the electron microscope during the 1930s—chemistry, biology, biochemistry, optics, microbiology, molecular biology, and DNA analysis.

In a 5-4 decision in Melendez-Diaz v. Massachusetts, the US Supreme Court ruled in June 2009 that defendants have the right to cross-examine forensic analysts who handle scientific evidence in criminal cases because a state forensic analyst's report used in a criminal prosecution is subject to the confrontation clause of the Sixth Amendment.

Forensic Medicine

Forensic medicine—the use of medicine to determine cause and manner of death—dates back to ancient Greece and the birth of medicine. From the inception of this discipline, medical practitioners have mastered techniques for determining the time and manner of human deaths. Forensic medical testimony is one of the oldest forms of scientific testimony and has been widely accepted in courts and legal systems across the world. With the advent of modern medicine in the sixteenth and seventeenth centuries, forensic medicine became irrevocably entrenched in the investigative process. In modern criminal justice, forensic medicine is a necessary part of any death investigation. Medical examiners oversee death investigations and may be called upon to testify in court regarding the facts surrounding deaths.

The Importance of Crime Scenes

The role of forensic science and medicine in the criminal justice system is to aid in the arrest and prosecution of criminals. When law-enforcement officers witness crimes, making arrests is easy. However, in real life, that rarely happens. Arrests that lead to successful convictions are dependent upon three things: witnesses who can testify well, crime scene evidence that can be processed and presented at court, and voluntary confessions by perpetrators. Not all three components need be present for convictions, but each component helps build the state’s case against criminal defendants.

Forensic science is most concerned with the processing of crime scenes. The importance of this work cannot be overstated. Criminal investigations begin at crime scenes; if they are not handled properly, the investigations may not progress any further. All the modern scientific advances available to law enforcement cannot make up for what is lost when crime scenes are not been properly guarded and preserved for forensic analysis. Crime scenes must be kept and processed in as pristine a condition as possible.

Depending upon the size of the law-enforcement departments responding to crimes, the responsibility for collecting evidence from crime scenes may fall to the responding officers, the lead detectives, or crime scene technicians. In large jurisdictions, specialists may collect different types of evidence. For example, fingerprint specialists dust for and lift fingerprints.

Evidence from crime scenes may be examined in three different ways. Physical methods, which are often used, include measuring sizes of objects and where they are in relation to each other; physical matching and comparisons—which are common with glass fragments—and photography. Since the advent of digital photography, the first responders have been able to photograph evidence and make prints quickly and easily, thereby helping to ensure that even transitory evidence, such as wet shoe prints, can be preserved.

Chemical methods are often used—especially in the processing of drug evidence. Before convictions can be obtained in drug cases, techniques such as chromatography and spectrography are employed to determine the chemical makeups of evidence at the scenes. Chemical analyses are also performed on blood-alcohol evidence. Biological methods, including microscopy, may also be used, especially when the evidence consists of minute fibers and fragments.

Training

Training within forensic medicine and forensic science is very diverse, depending upon the particular job descriptions. Forensic medicine requires medical degrees and advanced training. Crime scene technicians generally have college degrees or certificate training. Police officers who work at crime scenes may have on-the-job-training or take specific classes. Individuals who work in crime labs generally have either master’s or doctoral degrees in chemistry, biology, or other natural sciences.

Bibliography

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