forensic science

forensic science, the application of the methods of the natural and physical sciences to matters of criminal and civil law. Forensic science can be involved not only in investigation and prosecution of crimes such as rape, murder, and drug trafficking but also in matters in which a crime has not been committed but in which someone is charged with a civil wrong (see tort), such as willful pollution of air or water or causing industrial injuries.

Almost any science can be a forensic science because almost any science can contribute to solving a crime or evaluating a civil harm. In fact, with few exceptions, forensic sciences are no different in what they study than traditional sciences. The only difference is that forensic scientists apply the methods and techniques of established sciences to legal matters.

Short descriptions of each of the main areas of forensic science follow.

Forensic anthropology

There are a number of applications of anthropology to the forensic sciences. A large part of physical anthropology deals with skeletal biology, which includes bone and bone system structures and their relationships to characteristics such as gender, age, race, socioeconomic status, and so forth. That knowledge can be applied to the examination of characteristics of skeletal remains that are part of a crime scene. In such cases, the goal of the analysis may be to determine the identity of the deceased person and, perhaps, the cause of death. To those ends, forensic anthropologists make use of a number of unique techniques.

Two major types of human-remains evidence confront the forensic anthropologist. First is the single bone or bone fragment or small group of bones. When that is the only type of evidence present, the forensic anthropologist seeks to determine if the bone is human and, if not, what type of animal the bone belongs to. If the sample is human bone, then the anthropologist will determine the part of the body from which it came. For example, if a single human arm bone is recovered from a field, there will most likely be other human bones belonging to the same individual around also.

The second major type of forensic anthropological evidence is the complete (or nearly complete) skeleton. From that evidence, the accomplished forensic anthropologist may be able to determine gender, race, approximate age, stature, and approximate socioeconomic status. If there is damage to some of the bones, the anthropologist may be able to determine what type of trauma caused it. If the skull is present, it may be possible to prepare an approximate face on the skull using skull superimposition—building a face out of clay using average thickness measurements developed by anatomists, pathologists, and anthropologists. Investigators may then publish a picture of the face to see if it evokes a response from a relative of a missing person. If a possible match to the skeleton is found and there are antemortem pictures available, then a new video superimposition technique may be used. That technique utilizes two cameras to superimpose the skull over the picture of the actual face to determine if the skull could be the right one.

Criminalistics

Criminalistics can be defined as the application of scientific methods to the recognition, collection, identification, and comparison of physical evidence generated by criminal or illegal civil activity. It also involves the reconstruction of such events by evaluation of the physical evidence and the crime scene.

Criminalists, usually called “forensic scientists,” analyze evidence such as body fluids in order to determine if DNA in those fluids matches blood found at a crime scene (see DNA fingerprinting). Other forensic scientists may help identify, collect, and evaluate physical evidence at a crime scene.

Forensic engineering

Forensic engineering uses the concepts of mechanical, chemical, civil, and electrical engineering as tools in the reconstruction of crimes and accidents and the determination of their cause. A major component of that work involves traffic accident reconstruction. To determine what may have caused the accident, forensic engineers use evidence such as skid marks; damage to cars and their positions after the accident; road and environmental conditions; injuries to drivers, passengers, and pedestrians; and witness accounts. In developing their explanations, engineers may work in concert with forensic pathologists, toxicologists, criminalists, and other engineers. Some forensic engineers specialize in marine incidents or aircraft crashes.

Another major area of forensic engineering is failure analysis. Mechanical, chemical, civil, and structural engineers all bring their skills to bear on problems involving how and why buildings or other structures deteriorate or fail prematurely. An example of such work was the collapse of a walkway high above the lobby of the Kansas City Hyatt Regency Hotel in 1981, which killed and injured many people. Forensic engineers were called in to determine why the balcony collapsed.

A somewhat unusual application of forensic engineering involves animals on farms where high-voltage power lines or communication transmission lines pass overhead. For many years, there have been suggestions by farmers that transient currents from these power lines affect the health of their animals, including cows’ ability to give milk. Many electrical engineers have studied this problem and cases have ended up in court.

Forensic engineers are usually educated engineers who have earned a doctorate and who develop expertise in one or more of the forensically important disciplines. There are no university graduate programs in forensic engineering; most of the expertise is developed on the job, perhaps working with more-experienced practitioners.