Detection of Gunshot Residue by Use of the Scanning Electron Microscope

Abstract

Current methods used to determine whether or not an individual has fired a handgun are based on analyses of samples taken from various regions of the hand for total content of antimony, barium, and often lead. High amounts of these elements are considered to be characteristic of gunshot residue [1–11]. However, the ability to identify residue conclusively has been severely restricted by the environmental occurrence of these same elements. Results of the studies described in this paper indicate that, by combining information about the morphology of gunshot residue particles with elemental analysis of individual particles [obtained by using an X-ray analyzer with the scanning electron microscope (SEM)], it is possible to reach a conclusion of increased significance concerning the presence of residue as distinguished from environmental contamination. The results of extensive studies of residue particles and analyses of numerous hand samples are presented here. It has become apparent that the new technique is a major improvement and that it is moderately rapid when performed by a trained microscopist.

Passive Exposure and Persistence of Gunshot Residue (GSR) on Bystanders to a Shooting: Comparison of Shooter and Bystander Exposure to GSR

“…None of the bystanders had more than 4 GSR particles after this time. Particle retention on bystanders appears to be comparable to that of shooters as the loss rate was similar to that which has been reported for shooters (2,5,6). …”

“…Background samples were not collected from the bystanders prior to test-firing as their activities were controlled to exclude contact with firearms. Studies demonstrating the loss of GSR particles with time (2,4) and the effectiveness of hand washing in removing GSR (5) indicate that a 24 hour period and a thorough hand washing would be sufficient to remove any background GSR from the bystanders.…”

Gunshot Residues on Dry Bone After Decomposition—A Pilot Study

“…This last technique combines morphological information with the chemical analysis of each particle detected (10,11). It is widely available, relatively cheap, and the search procedure can be automated (12,13). To the best of our knowledge, most of the articles on the detection of GSR by SEM/EDX have so far examined GSR collected from the hands of the persons involved in shooting and from other objects near a gun after firing (10,11,14–16)—very few articles on GSR from gunshot in bone have been published.…”

DNA typing of cellular material on perforating bullets

“…Nesbitt et al 1976;DeGaetano and Siegel 1990) can lead to the identification of the person shooting. But in cases where more than one person fired a gun or where several persons were injured or killed, it is extremely difficult to determine who shot whom, especially when the bullets have perforated and therefore exited from the victim.…”