Microscopic examination of the skin around gunshot entrance wounds may reveal the presence of soot, hemorrhage, and bone fragments.

The microscopic identification of soot surrounding and within a gunshot wound is used by forensic pathologists to narrow the range of fire – that is, the distance between the barrel of the gun and the victim. While it’s well-known that firing a gun discharges a bullet, less obvious are the other substances which also exit the barrel. The effects of flame, soot, and unburned gunpowder allow a skilled pathologist to classify the entrance as a contact (in which the muzzle is pressed into the skin), near-contact, intermediate, or distant wound. Contact wounds often demonstrate thermal injuries of the wound edge and soot in the bullet track, whereas near-contact wounds will deposit soot (burned gunpowder) adjacent to the gunshot wound. As the distance between the end of the gun barrel and the
victim increases, the likelihood that fragments of unburned gunpowder (called “stippling”) will mark the skin surrounding the gunshot wound increases. Distant gunshot wounds will demonstrate no soot, stippling, or thermal injury to the edges of the wound.
The blackening of skin associated with thermal injury and soot deposition can be difficult to distinguish with the naked eye, but are distinctively different under the microscope. This image shows the presence of brownish-black soot within the gunshot wound, consistent with a contact wound; also identifiable are skin, red blood cells consistent with acute hemorrhage, and a small bone fragment.