1. Gunshot Residue Analysis
STEM

2. Gunshot Residue (GSR) Two types:
GSR deposited on victim, clothing or target that follows the path of the bullet
GSR deposited on the shooter’s hands primarily from the primer

3. Gunshot Residue (GSR) Gunpowder Chemistry
Major detectable elements are: lead (Pb), barium (Ba) & antimony (Sb)
Virtually all cartridge cases are made of brass (copper & zinc); also detectable.

4. GSR: A Revolver Being Fired

5. GSR: The Firing of an AK-47

6. Chemical Testing of GSR
Modified Griess Test
Specific for partially burned and unburned gunpowder particles, most specifically, nitrates found in the partially burned gunpowder
Sodium Rhodizonate Test
Specific for lead
Vaporous lead is usually found closer than arm’s length

7. Results of GSR Hand Test
Negative results may be caused by:
Washing the hands
Shooter may have been wearing gloves
Lead free ammunition
A rifle or shotgun may not deposit GSR on hands

10. GSR on the hand of a suicide victim, proving he was holding the weapon when it was fired.

11. GSR Testing of Hands Swabs are taken of the suspected shooter(s) hands
Examined under the Scanning Electron Microscope (SEM)
Tests for Lead, Antimony, and Barium particles
Studies suggest it stays on the hands approximately for 6 hours

12. SEM of GSR Particle

13. Any Questions?

14. Video: Gunpowder signature may help solve crimes (2.5 min)

15. References
Richard Ernest Forensic Ballistic Consultant website:
Introduction to Forensic Firearms Identification website:
This presentation is available because of the expertise of John Romeo, Firearms Analyst with the Florida Dept. of Law Enforcement