Forensic Science

I

Introduction

Forensic Science or Medical Jurisprudence, also called forensics, the application of science to law. Forensic science uses highly developed technologies to uncover scientific evidence in a variety of fields.

Modern forensic science has a broad range of applications. It is used in civil cases such as forgeries, fraud, or negligence. It can help law-enforcement officials determine whether any laws or regulations have been violated in the marketing of foods and drinks, the manufacture of medicines, or the use of pesticides on crops. It can also determine whether automobile emissions are within a permissible level and whether drinking water meets legal purity requirements. Forensic science is used in monitoring the compliance of various countries with such international agreements as the Nuclear Non-Proliferation Treaty and the Chemical Weapons Convention and to learn whether a country is developing a secret nuclear weapons program. However, forensic science is most commonly used to investigate criminal cases involving a victim, such as assault, robbery, kidnapping, rape, or murder.

II

The Medical Examiner

The medical examiner is the central figure in the forensic investigation of crimes involving a victim. It is the responsibility of the medical examiner to visit the crime scene, conduct an autopsy (an examination of the body) in cases of death, examine the medical evidence and laboratory reports, study the victim's medical history, and put all this information together in a report to the district attorney.

Medical examiners are usually physicians specializing in forensic pathology, the study of structural and functional changes in the body as a result of injury. Their training and qualifications most often include a medical degree and an apprenticeship in a medical examiner's office. Depending on the requirements of the particular state, city, or county, the medical examiner may also be required to be certified as a forensic pathologist by the American Board of Pathology. At present, the United States has no national system of medical examiners and has no federal law requiring that coroners be licensed physicians.

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III

Forensic Scientists

Within the broad area of forensic science, there are many subspecialties, including pathology (the examination of body tissues and fluids), toxicology (the study of poisons, including drugs), odontology (the study of teeth), psychiatry, anthropology (the study of human beings), biology, chemistry, and physics. The medical examiner may call upon forensic scientists who are specialists in these various fields for help in investigating a crime. For example, whenever it is suspected that drugs or poisons are involved in a crime, the medical examiner must obtain the services of a toxicologist. Toxicologists detect and identify any drugs or poisons present in a person's body fluids, tissues, and organs. This type of investigation is conducted not only on the victim but, when possible, also on the suspected perpetrator of the crime.

Forensic odontologists examine and characterize the teeth of unidentified bodies when fingerprints or other identification is not available. The dental charts of missing individuals can then be compared with the forensic odontologist's report to identify the body.

Forensic anthropologists are trained to determine the sex, height, weight, and ethnic group of a deceased person from an incomplete body. Marks on the bones often indicate past injuries, diseases, and occupational stresses suffered by the individual. Investigators can identify a body by comparing old X rays and the medical history of a missing person with the findings of the forensic anthropologist.

Forensic scientists may choose to be certified by the American Board of Criminalistics, a professional organization that has developed examinations to certify individual forensic scientists in their particular area of expertise.

IV

Examining Evidence

The medical examiner investigates many different types of violent crime to determine whether a violent death was an accident, a suicide, or a homicide (murder). In all cases, the medical examiner must conduct an investigation of the crime scene and also an autopsy.

In cases involving gunshot wounds, the medical examiner looks for gunpowder residues on the clothing of the victim and around wounds. This information is used to estimate how far away the gun was when the victim was shot and to determine whether the gun was fired by the victim or someone else.

In the case of knife wounds, the medical examiner must distinguish between a cut (an injury that is longer than it is deep) and a stab wound (an injury that is deeper than it is long). The examiner also looks for defense wounds, cuts caused when an intended victim grabs the knife of an assailant in self-protection.

Cuts, rather than stabs, are associated with suicide. Usually the body has numerous superficial parallel cuts, indicating repeated and hesitant trials before the individual was able to make the final deep cut. Such cuts are called hesitation wounds, and they indicate a suicide rather than a homicide, which typically consists of a single deep gash.

Medical examiners are also called upon to investigate cases of asphyxiation—that is, death from lack of oxygen in the blood. Asphyxiation may be caused in a number of different ways, such as hanging, which may be an accident, suicide, or homicide, or strangulation, which is homicide. Obstruction of the victim's air passage by an object in the throat or compression of the victim's chest by a person or an object can also result in asphyxiation. Finally, asphyxiation can be caused by the replacement of oxygen in the red blood cells by another gas, as in carbon monoxide poisoning, which can be the result of suicide, homicide, or accident.

In a death involving carbon monoxide poisoning, a closed garage door and no marks on the body are usually taken as an indication of suicide, whereas the presence of tools around the car and grease on the victim's hands points to accidental death. The presence of a wound caused by a blow to the head or the absence of carbon monoxide in the blood of the victim would indicate an attempt to make a homicide look like a suicide.

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