Challenges and Opportunities: A Qualitative Study on Tax Compliance in Pakistan
Firearms 2
1.
2. 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
3. GSR
When gases combust
Propel bullet
Blow out from ejector
port and muzzle
GSR
Ejector particles
Combustion
residue
Unburned powder
particles
4. GSR – travel 3 – 5 feet
As firearm gets closer – the residue concentrations
increase
5. Elements contained in GSR are not water soluble
therefore the residue will remain on clothing
7. Greiss Test
Performed 1st does not interfere with later tests
Detects nitrites (product of combustion)
Used to determine muzzle to garment distance
8. 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
9. Steps continued
Acetic acid will react with nitrites and chemicals in
photographic paper
Resulting in orange specks
10. 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
15. 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
16. 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
17. GSR results - 3 categories
Residue, firearm and ammunition found
Residue found – firearm and ammunition not found
Trace or no residue found
18.
19. Gunshot wounds are typically classified as
Contact
Intermediate range
Distant range