Detection of bone and bone-plus-bullet particles in backspatter from close-range shots to heads

Abstract

A victim was shot in the head with a 9-mm Smith & Wesson pistol using Winchester Silvertip hollow-point ammunition. Of interest in this case was the distance from the muzzle of the weapon to the victim's head, since the wound characteristics were equivocal for firing distance. Two other handguns (revolvers) were involved in this shooting, in addition to a revolver owned by the victim. The handguns were sampled using tape lifts, and the casings were sampled by washing them in distilled water, followed by vacuum filtration of the washing water through 0.2-microns-pore Nuclepore filters. These materials were examined by scanning electron microscopy/energy-dispersive X-ray analysis. Calcium-phosphorous (bone) particles were detected on the 9-mm Smith & Wesson pistol, on two casings found at the scene, and on one of the revolvers. Two of the calcium-phosphorous particles on the casings had associated bullet fragments. Test shots on live pigs destined for slaughter showed that bone particles are a feature of backspatter from close-range shots to heads. Contamination of nearby surfaces by bone fragments and bone-plus-bullet fragments, as well as other organic debris, appears to be quite heavy.