by Kenneth Ujevich
When a gun is fired, the majority of gunshot residue (GSR) is deposited on the shooter’s hands. But these residues disappear through contact with surfaces or washing, leaving the maximum time frame to find GSR on a suspect’s hands to be 8 hours. The mucus on the inside of the nostrils forms a surface layer where they are able to trap foreign particles. In this way, mucus inside of a gunshot suspect’s nostrils could act like an adhesive medium to stick on it gaseous particles from a gunshot. In this study, the presence of GSR in nasal mucus and its residence time is examined. Samples are taken with cotton swabs moistened with a solution of EDTA and, after an acid digestion, are analyzed by graphite furnace atomic absorption spectrometry (AAS). In addition, samples of hands are taken for comparison purposes. The concentration of GSR in nasal mucus was found to be lower than on the hands, but with a longer residence time. Thus, it is possible to expand the sampling time of a suspect also, as nasal mucus cannot be contaminated by handling weapons.
Marina Aliste, Luis Guillermo Chávez. “Analysis of gunshot residues as trace in nasal mucus by GFAAS.” Forensic Science International. Volume 261, April 2016, Pages 14-18, ISSN 0379-0738, http://dx.doi.org/10.1016/j.forsciint.2016.01.034.