Thursday, January 24, 2008

A Lesson in Forensics

This is why we take samples from a shooting suspect's hands and clothing.

Look at the cloud surrounding the hands of the shooter. This cloud is comprised of gunpowder and primer residue. In gunshot residue tests, certain elements are sought to indicate that residue from a gunshot is present on the hands, gloves or shirt cuffs of the suspect. One of the components of pistol/rifle primers is barium and it turns up in these residue tests.

Gunshot residue can also be found on the clothing of the victim if he is close enough to the shooter. I have had cases where someone claimed to be shot from a distance but the gunshot residue deposited on his clothing indicated that the shot was fired from a distance of only a few feet or less. In one investigation I examined the clothing of an alleged victim who reported that he had been shot from a passing car. It isn't rocket science - the powder residue was thickly disturbed right around the bullet hole in his jeans He had actually shot himself in the leg with an illegal handgun.

Also notice the shock waves. There are two sources - the muzzle of the barrel and the front of the revolver's cylinder. The "nipple" at the left end of the shock wave is actually the bullet leaving the barrel.

H/T to Paul C for this great photograph.

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