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Analysis of the Results of Gunshot Residue Detection in Case Work

NCJ Number
Journal of Forensic Sciences Volume: 25 Issue: 4 Dated: (October 1980) Pages: 839-846
E Rudzitis
Date Published
8 pages
The results obtained from 827 actual criminal cases by analyzing the contents of 1,250 gunshot residue (GSR) kits over a 6-year period are described.
A statistical treatment is also presented that establishes a consistent method for evaluating an analysis of a particular GSR test kit in terms of an inconclusive or GSR-consistent opinion. During the 6-year period three different techiques were used: from 1974 through 1976 neutron activation analysis (NAA) was used; in 1977, atomic absorbtion spectrometry (AAS) was used; and AAS for barium and NAA for antimony were used in 1978 and 1979. In 55 percent of the kits, the presence of both barium and antimony in levels greater than the established percent of the kits, the presence of both barium and antimony in levels greater than the established averages determined the opinion of GSR-consistent. Concerning the advantages of swabs from the back of the hand and palm as compared to rinses of the total hand in a plastic bag, it was found that in GSR-consistent suicide cases 70 percent had sufficient GSR on the back of the hand and only in 30 percent was the opinion based on residue on the palm only. Moreover, incidence of finding GSR on the right hand exceeded that on the left. Another correlation was the effect of caliber on GSR-consistent findings. It was found that a .38 caliber weapon gave 61 percent and .22 calibers gave 39 percent. A combination of neutron activation and atomic absorption analysis was found to be the most efficient mehod for the determination of trace amounts of antimony and barium on swabs. Tables and 9 references are provided.


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