Gunshot residue (GSR) , also known as cartridge exhaust residue (CDR), "residual shoot" (GFR), or firearm residue residue (FDR), is the residue stored in the hands and the clothes of a person releasing firearms. It mainly consists of burned and unburned particles of primary explosives, propellants - and possibly bullet fragments, cartridge boxes, and firearms.
Law enforcement researchers tested people's clothing and skin for the GSR to determine if they were near weapons when released. The shot residue can travel a distance of 3-5 feet (0.9-1.5 meters) from the gun. At the furthest distance, only a few trace particles can be present.
Video Gunshot residue
History
In 1971 John Boehm presented some GSR particle micrographs that were discovered during the bullet entrance examination using a scanning electron microscope. If the scanning electron microscope is equipped with an energy-dispersive dispersion-energy dispersion spectroscopy detector, the chemical elements present in such particles, especially lead, antimony and barium, can be identified.
In 1979 Wolten et al. proposed a GSR classification based on composition, morphology, and size. Four compositions are considered characteristics :
- Lead, antimony, and barium
- Barium, calcium, and silicon
- Antimon
- Barium
The authors propose some rules about chemical elements that can also be present in these particles.
Wallace and McQuillan published a new classification of GSR particles in 1984. They are labeled as unique particles containing lead, antimony, and barium, or those containing antimony and barium. Wallace and McQuillan also stated that these particles can only contain several chemical elements.
Maps Gunshot residue
Current practice
In the latest ASTM Standard Guidelines for GSR analysis with Scanning Electron Microscopy/Energy Dispersive X-ray Spectrometry (SEM-EDX) particles containing lead, antimony and barium, and respect for some rules related to morphology and the presence of other elements are considered GSR characteristics. The most definitive method for determining whether a particle is characteristic or consistent with GSR is with its element profile. An approach for identification of particle characteristics or consistent with GSR is to compare the profile of particle elements taken with those collected from specific known source items, such as recovered weapons, Cartridge cases or items related to the victim whenever necessary. This approach is called 'case by case' by Romolo and Margot in an article published in 2001. In 2010 Dalby et al. published a recent review on the subject and concluded that the adoption of a "case by case" approach to GSR analysis should be seen as better, in accordance with Romolo and Margot.
Given the similar particles generated from foreign sources, both Mosher et al. (1998) and Grima et al. (2012) presenting evidence of pyrotechnic particles that could be misidentified as GSR. Both publications highlight that certain markers of exclusion and reference to the general population of collected particles can assist experts in determining the same GSR-particle as fireworks.
Particle analysis by scanning electron microscope equipped with X-ray dispersive-energy spectroscopy detector is the most powerful forensic tool that can be used by researchers to determine the subject's proximity to the use of firearms or contact with GSR-exposed surfaces (firearms, spent cartridges) , target hole). The accuracy of a test requires a procedure that avoids the transfer of secondary shoot residues from the police officer to the subject or item to be tested, and which avoids contamination in the laboratory.
Two main groups of specialists currently active in shooting residue analysis are the US-based Scientific Working Group for Weapons Residues (SWGGSR) and the EWG ENFSI-based GSR Working Group/GSR in Europe.
Results
Positive results for GSR from SEM-EDX analysis can mean many things. Particularly it shows that the person whose sample is taken is around the gun when fired, handled with a gun after being fired, or touching something that is around the gun when fired. (For example: When someone goes to the aid of a gunshot wound, some GSR particles can transfer from the victim.)
Negative results can mean that the person is not near the gun when fired, or that they are nearby but not close enough for the GSR to land on them, or it could mean that the GSR stored on them is lost. GSR is the consistency of flour and usually only lasts in the hands of people living for 4-6 hours. Wiping the hands on anything, even putting them in and out of the bag can move the GSR from the hand. Victims do not always get GSRs; even suicide victims can test negatively for GSR.
Match GSR to a specific source
If the ammunition used is specifically marked in some way by a special element, it is possible to know which cartridge is used to produce the GSR. The conclusions about GSR sources can be based on examination of the particles found in the suspect and the population of the particles found on the victim, in firearms or in the case of cartridges, as suggested by the ASTM Standard Guide for GSR analysis by Scanning. Electron Microscopy/Dispersive Energy Spectrometry X-ray. Advanced analytical techniques such as Ion Beam Analysis (IBA), conducted after Scanning Electron Microscopy, can support further information that makes it possible to infer the source of GSR particles. Christopher et al. shows as the grouping behavior of different brands of ammunition can be determined by using multivariate analysis. Bullets can be reconciled with pistols using comparative ballistics.
Organic shotgun residue
The residue of organic guns can be analyzed by analytical techniques such as chromatography, capillary electrophoresis, and mass spectrometry.
See also
- Blowback, the material drawn into the barrel of the firing post release
References
- ASTM E1588-10e1, Standard Guide for GSR analysis by Scanning Electron Microscopy/Energy Dispersive X-ray Spectrometry, American Society for Testing and Materials, West Conshohocken, PA, 2010.
- E. Boehm, SEM Application in forensic medicine, Scanning Electron Microscopy (1971) 553-560.
- M Christopher, J Warmenhoven, FS Romolo, M Donghi, R Webb, C Jeynes, NI Ward, New Quantitative Methods for Gunshot Residue Analysis by Ion Beam Analysis. Analyst, 2013, 138, 4649.
- O. Dalby, D. Butler, J.W. Birkett, Analysis of Rifle Residues and Related Materials - Reviews, J. Forens. Sci. 55 (2010) 924-943.
- M. Grima, M. Butler, R. Hanson, A. Mohameden, Firework is presented as a source of particles similar to shoot residue, Science and Justice 52 (1) (2012) 49-57.
- HH. Meng, B. Caddy, Gunshot residue analysis - reviews, J. Forens. Sci. 42 (1997) 553-570.
- P.V. Mosher, M.J. McVicar, E.D. Randall, E.H. Sild, Shoot-like residue-particles produced by fireworks, Journal of the Canadian Society of Forens. Sci. 31 (3) (1998) 157-168.
- F.S. Romolo, P. Margot, Identification of shot residue: critical review, Forensic Sci. Int. 119 (2001), 195-211.
- F.S. Romolo, M.E. Christopher, M. Donghi, L. Ripani, C. Jeynes, R.P. Webb, N.I. Ward, Ion Integrated Ion Analysis (IBA) in Gunshot Residue characterization (GSR). Forensic Sci. Int. 231 (2013), 219-228.
- A.J. Schwoeble, D.L. Exline, Current Methods in Forensic Gunse Residue Analysis, (2000) CRC Press LLC.
- J.S. Wallace, J. McQuillan, the release residue of a cartridge-operated industrial apparatus, J. Forens. Sci. Soc. 24 (1984) 495-508.
- J.S. Wallace, Gunshot Chemical Guns, Ammunition and Residue Analysis, (2008) CRC Press LLC.
- G.M. Wolten, R.S. Nesbitt, A.R. Calloway, G.L. Loper, P.F. Jones, Particle analysis to detect shot residue. I: Scanning electron microscopy/energy dispersive X-ray characterization of hand sediment from shot, J. Forens. Sci. 24 (1979) 409-422.
- G.M. Wolten, R.S. Nesbitt, A.R. Calloway, G.L. Loper, Particle analysis to detect shot residue. II: work particles and environment, J. Forens. Sci. 24 (1979) 423-430.
- G.M. Wolten, R.S. Nesbitt, A.R. Calloway, Analysis of particles to detect shot residue. III: case note, J. Forens. Sci. 24 (1979) 864-869.
External links
- New Scientist , November 23, 2005, "Why can not we rely on forensic firearms"
- Scientific Working Group on Weapons Residues (SWGGSR) http://www.swggsr.org/
- ENFSI EWG Firearms/GSR Working Group http://www.enfsi.eu/about-enfsi/structure/working-groups/firearms-and-gsr
- Gunshot Powder Residue Exam http://www.meditests.com/gun-powder-test.html
Source of the article : Wikipedia
0 Comments