NCJ Number
207707
Journal
Journal of Forensic Sciences Volume: 49 Issue: 6 Dated: November 2004 Pages: 1237-1243
Date Published
November 2004
Length
7 pages
Annotation
This study used high-speed stroboscopic photography (spark gap light source) to measure the velocity of over 800 gunshot residue particles from 8 different sources.
Abstract
Prior to this study there had been no detailed study of the propellant particle velocity and distribution upon impact. In addition to velocity, other factors that may affect particle distribution are the wind, movements of the suspect or victim, as well as other factors. The description of methods and materials encompasses the high-speed flash system, the specifications and use of the oscilloscope, the digital flowmeter, cameras and related accessories, the digital caliper, the handgun machine rest, the types of firearms used, the photographic arrangement, and the particle experiments. The study found that the particles acquired surprisingly high velocities from the propellant ignition, thus giving them sufficient energy to embed them within nearby targets composed of skin or fabric. Upon impacting skin, the particles produce punctate wounds associated with stippling (powder tattooing). Although no particles may be apparent on the upper surface of a garment or upholstery fabric, it should not be assumed that no gunshot residue is present. Because of their relatively high velocity near the firearm muzzle, normal wind velocity will not significantly influence the motion of propellant particles that produce stippling. 9 figures, 3 tables, and 7 references