Law-enforcement technologyIdentifying ammunition, gun used to commit a crime
New, Raman spectroscopy-based gun-shot residue (GSR) analysis technique would make it possible for forensic investigators to match minute amounts of GSR to the exact type of ammunition, and the caliber of the gun, used to commit a crime
New analysis technique can identify the firearm and ammunition type // Source: bilahdood.net
The ability unequivocally to identify a gunshot residue (GSR) when a firearm is discharged is an important, even crucial, part of crime scene investigation. In a recent research report, María López-López and colleagues write that to date, the great majority of the analyses have focused on the inorganic components of gun-shot residue (GSR). The introduction of lead-free or nontoxic ammunitions, however, makes it difficult to prevent false negatives.
The new study, published in the current issue of Analytical Chemistry, introduces a fast methodology, using Raman spectroscopy, for the organic analysis of GSR.
Six different types of ammunition were fired at short distances into cloth targets, and the Raman spectra produced by the GSR were measured and compared with the spectra from the unfired gunpowder ammunition. The GSR spectrum shows high similarity to the spectrum of the unfired ammunition, allowing the GSR to be traced to the ammunition used. Additionally, other substances that might be found on the clothes of the victim, shooter, or suspect, and which might be confused with GSR, such as sand, dried blood, or black ink from a common ballpoint pen, were analyzed to test the screening capability of the Raman technique. The results obtained evidenced that Raman spectroscopy is a useful screening tool when fast analysis is desired, and that little sample preparation is required for the analysis of GSR evidence.
— Read more in María López-López et al., “Ammunition Identification by Means of the Organic Analysis of Gunshot Residues Using Raman Spectroscopy,” Analytical Chemistry (15 March 2012) (DOI: 10.1021/ac203237w); and Ingeborg E. Iping Petterson et al., “Noninvasive Detection of Concealed Explosives: Depth Profiling through Opaque Plastics by Time-Resolved Raman Spectroscopy,” Analytical Chemistry 83, no. 22 (3 October 2011): 8517–23 (DOI: 10.1021/ac2018102)
