Firearms 2

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  • 3 inches, 12 inches, 18 inches greater than 3 inches but less than 18 inches.
  • No GSR on skin because all GSR is inside the body
  • Firearms 2

    1. 1. Bullet Holes The bullet holes are smaller in diameter than the bullet due to the elasticity of the fabric Higher the velocity = the greater the damage Bullet wipe residue – traces of lead leave a ring of residue
    2. 2. GSR When gases combust  Propel bullet  Blow out from ejector port and muzzle GSR  Ejector particles  Combustion residue  Unburned powder particles
    3. 3.  GSR – travel 3 – 5 feet As firearm gets closer – the residue concentrations increase
    4. 4.  Elements contained in GSR are not water soluble therefore the residue will remain on clothing
    5. 5. GSR Examinations Visual/Microscopic Examination Greiss Test Sodium Rhodizonate
    6. 6. Greiss Test Performed 1st does not interfere with later tests Detects nitrites (product of combustion) Used to determine muzzle to garment distance
    7. 7. Steps of Greiss Test Treat photographic paper with chemical mixture – paper will no longer be light sensitive but will be reactive to the presence of nitrite residues Particle being processed placed faced down against treated photo paper – bullet hole centered Steam ironed - dilute acetic acid
    8. 8. Steps continued Acetic acid will react with nitrites and chemicals in photographic paper Resulting in orange specks
    9. 9.  Using same firearm – make test samples from various distances Determine  Minimum firing distance (the gun could be no closer than)  Maximum firing distance (the gun could be not any further than
    10. 10. Greiss Test – 3 inches
    11. 11. Greiss Test – 9 inches
    12. 12. Greiss Test – 15 inches
    13. 13. Greiss Test – 21 inches
    14. 14. Sodium Rhodizonate Test Determines if lead residues are present Spray particle with sodium rhodizonate solution (dark yellowish/orange color) Sprayed with buffer solution – causes background color to disappear
    15. 15. Sodium Rhodizonate Test Sodium rhodizonate reacts with lead – very bright pink Pink – only indication of presence of lead To confirm – area treated with Hydrochloric acid If pink turns blue – presence of lead confirmed
    16. 16. GSR results - 3 categories Residue, firearm and ammunition found Residue found – firearm and ammunition not found Trace or no residue found
    17. 17. Gunshot wounds are typically classified as  Contact  Intermediate range  Distant range
    18. 18. Contact barrel contacts the skin the gases released cause the star-shaped laceration.
    19. 19. ContactThe abrasion ring, and a very clear muzzle imprint, are seen in this contact range gunshot wound.
    20. 20. intermediate Powder tattooing The actual entrance site is somewhat irregular, because the bullet can tumble in flight.

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