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GSR
Gunshot residue is composed of burnt and unburnt particles from the firearm's primer, propellant, bullet, cartridge case, and firearm. There are three types of gunpowder burning - degressive, neutral, and progressive. Gunshot residue can be detected through analytical methods like neutron activation analysis and atomic absorption spectrophotometry, and qualitatively identified with scanning electron microscopy and atomic force microscopy. Gunshot residue is collected using carbon-coated adhesive stubs or alcohol swabs, with stubs having fewer false negatives. Firing distance can be determined using tests like the Greiss test, which can help identify homicide versus suicide or entrance versus exit wounds. Each gunshot residue case must be individually evaluated as test results alone do
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GSR
- 1. Topic -Gun shotresidue By- Jagrati Sharma To- Ketan Sir
- 2. CONTENTS .What is gunshot residue? .Appearances of gun powder .Detection of gun shot residue .Collection of gun shot residue .Distance .Conclusion
- 5. It is principallycomposed of burnt and unburnt particles from the explosive primer, the propellant and possibly fragments of the bullet, cartridge case, and the firearm.
- 6. Degressive (regressive) burning: gunpowdergrains formed in flakes, balls, and sticks have a burning surface area that decreases continuously as the grains are consumed. Neutral burning: gunpowder grains that are single perforated and the burning surface area remains relatively constant.
- 7. Progressive burning: gunpowder grainsthat are multi- perforated and rosettes that have a burning surface area that increases continuously as the grains are consumed.
- 8. DETECTION OF GUNSHOTRESIDUE The major methods for detection of primer residues are analytical and qualitative. Analytical methods include neutron activation analysis (NAA) as well as atomic absorption spectrophotometry (AAS) and inductively coupled plasma mass spectroscopy (ICP-MS). Scanning electron microscopy with energy dispersive analysis by x-ray detector (SEM-EDX) and atomic force microscopy (AFM) are used to identify the primer residue qualitatively.
- 9. COLLECTION The method ofcollection for residue is quite simple and easily carried out in the field. The two widely used methods include collection onto a carbon- coated adhesive stub or with an alcohol swab. Of the two, the stub has fewer false negatives from greater collection efficiency. The swab method may have usefulness when the surface to be tested is smooth, or if propellant analysis is required.
- 10. DISTANCE Firing distance determinationis a common factor in investigations. Saferstein (2006) states that using the Greiss Test method provides a more contrasted view of GSR on a surface. DiMaio (1999) states that using Greiss Test results can help determine whether a case is a homicide or a suicide. Brazeau and Wong (1997) say that using GSR tests can also help determine whether a bullet wound is an entrance or an exit wound.
- 11. CONCLUSION There are notwo cases that are completely and indisputably the same. That is why each case has to be looked at individually. Investigators need to take the time to evaluate the results of any tests and evidence, including gunshot residue.
- 12. Just because agunshot residue comes back negative does not necessarily mean there was never and residue there.
- 13. The same goesfor a positive result, just because a test comes back positive does not necessarily mean that that person was the shooter or held the gun.
- 14.