NCJ Number
88834
Date Published
1981
Length
13 pages
Annotation
A practical and effective method of detecting firearm discharge residues on hands is the quantitative determination of lead by atomic absorption spectrophotometry and antimony and barium by neutron activation analysis.
Abstract
To determine whether or not a person has fired a gun, six factors are considered: the absolute amounts of lead, antimony, and barium, and the ratios of each of these amounts on one hand compared with the other. Neutron activation analysis for antimony and barium has been considered the most effective technique for the detection of gunshot residues on the hands; however, the method is not used routinely because of the complex nature of the statistical treatment of the data and the difficulty experienced by laboratories in collecting the voluminous background data required for these calculations. Neutron activation analysis is not effective in detecting lead, so a method such as atomic absorption spectrometry must be used to detect lead. Tests have shown that the amounts of lead, antimony, and barium, as well as the ratios, were higher on hands that have fired a gun than on normal hands. In the case of an actual firing, the point count on the firing hand is greater than 5, while it is usually below 5 for the other hand. If the gun has merely been handled in a random manner but not fired, residues are usually left on both hands, with the point count for both hands being above 5. The proposed method has been successfully tested in 20 simulated cases with only one false positive detected and that with a police officer, who frequently handles or fires guns. Testing methodology and tabular data are provided.