Abstract
Gunpowder residues have long been important as evidence in the investigation of firearms cases, particularly in the reconstruction of crime scene events. Early work was based solely on the spatial distribution of unburned powder and its relationship to the distance between the target material and the weapon's muzzle. Current refinements have included mathematical analysis of these patterns and the identification of patterns of trace metal transfers of bullet lead, copper, and zinc, or primer lead, barium, and antimony by neutron activation, atomic absorption, or X-ray fluorescence.