Examining Evidence

Forensic Science Examining Evidence

Introduction to 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.” (1)

Resources

Notes and References

• Information about Examining Evidence in the Encarta Online Encyclopedia

Guide to Examining Evidence