Knife Wounds

When investigating an assault or murder , the pattern of injuries to a victim can provide clues as to the nature of the weapon used. For example, the angle of a gunshot wound and the deposition pattern of the gunshot residue can be valuable to a forensic investigator in determining the location from which the gun was fired. Similarly, for knife wounds, the pattern of injury can be a clue to the knife that was responsible.

The pattern of a knife injury can also be a clue to the nature of an attack. For example, a slashing motion can inflict long but superficial cuts, whereas a jab can produce a deep puncture wound . A forensic investigator may be able to gauge the timing of the blows, to determine which of the blows may have dispatched the victim.

Because a knife can retain some of the victim's blood (and even that of the assailant), and because the knife needs to be held to be effective, a knife can be a storehouse of forensic information. Blood types, skin cells that house DNA , and fingerprints may all be present on a knife recovered at a crime or accident scene.

Knives come in all shapes and sizes. At the extremely small end of the scale, for example, are thumb knives, lapel daggers, and coin knives. Developed by the British in World War II, the coin knife looks like an ordinary piece of pocket change. The blade itself is crescent-shaped, and attaches to the back by a small hasp so that it can rotate outward. It is too blunt to be used for inflicting grievous bodily harm.

Knives and daggers have been concealed in belts (that is, on the inside of the belt and parallel to it), in belt buckles, and even in the plastic arms of eyeglasses. But, when the aim is to attack someone, a large knife is desirable. Domestically, kitchen knives often become the preferred choice.

Most formidable-looking of all is the Fairbairn-Sykes fighting knife, developed in World War II by two British officers, W. E. Fairbairn and E. A. Sykes. Based on knowledge gained from their experience in close combat while serving with the Shanghai police, the knife would quickly dispatch a victim by striking at his vital organs. Its blade was long, but the handle was nearly as lengthy, so as to ensure great control on the part of the user. First produced in 1941, it was readily adopted by Allied forces. British commandoes carried it on raids into Norway, and the United States Office of Strategic Services (OSS), which employed Fairbairn as an instructor, developed its own version. Revised over the years, the knife remained in production through the 1990s.

see also Crime scene investigation; Death, cause of; Puncture wound; Wound assessment.