Gunshot Residue

Brandon Riney, Bell Mueller, Stone Ormand, Dillon Knowlton

Physical Properties

-it is not always visible to the naked eye

-left at a crime scene and all over the guns muzzle

-the blowback (material that is scattered backward from the direction of a force blow) covers the shooters hand as well as along the perimeters of the gun.

-Some times they can tell what kind of bullet the shooter used from the GSR left on the body which can lead them to what gun was used for the murder

Chemical Properties

-Gunpowder—regardless of the formulation—has one specific purpose: the creation of oxides of carbon; in particular, carbon dioxide. The rapid creation of this gas is the propelling force that pushes a projectile (bullet) down through the barrel and on toward its intended target.


-GSR: gunshot residue consisting of burned and unturned powder, vaporized, and particulate lead, primer residues of lead, barium, and antimony.


-Old formula: mixture of saltpepper (potassium nitrate), charcoal, and sulfur.

-New formula: original formula plus added Cordite (to eliminate the sulfur), nitrocellulose (guncotton), and glycerol trinitrate (nitroglycerin).


Sodium Rhodizonate Test: a color test for the presence of lead in gunshot residue.

Greiss Test: a color test for the presence of nitrite in gunpowder residue.

Some examples of what it looks like

How Forensic Scientists use it in the Lab

The gunshot residue can be swabbed from the skin or clothing of the suspected shooter (as long as it didn't involve a gun where the primer chemicals eliminate metals). For example, if a man kills himself with a handheld gun, he will undoubtedly have residue on his hand. It can be subjected to analysis for its composite content under the scanning electron microscope. (Some labs use a different method.) One problem is that just standing near a gun when fired can result in gunshot residue. Yet the experts can still examine relative amounts and make educated guesses.

- In simpler words, gunshot residue is tested to see if people had been involved in the discharge of a firearm.

Gun Shot Residue test

Bibliography

Deslich, Barbara, and John Funkhouser. "Gunshot Residue." Forensic Science for High School. Dubuque, IA: Kendall/Hunt, 2006. 451-52. Print.


Penven, Don. "Free Newsletter." Gun Shot Residue Testing. Crime Scene Resources, Inc., n.d. Web. 05 Feb. 2014.