| It is the goal of gunshot residue (GSR) analysis to | | | | Chemical analysis looks closely for byproducts of the |
| put the suspect near a firearm when it is fired. | | | | burning of primer and gun powder. Specifically, |
| Unfortunately, being near the gun when it goes off | | | | forensic scientists look for the metals lead, antimony, |
| or simply handling the gun afterward can leave behind | | | | and barium. The Q-tip or filter paper is then treated |
| GSR on an innocent individual. GSR testing must be | | | | with a solution of diphenylamine, a chemical that |
| conducted right away after a gun is fired because | | | | interacts with metals by producing a color change. |
| GSR tends to fade away quickly and usually | | | | The test is positive if the color blue is produced. |
| disappears after approximately two hours. | | | | However, this test could be a false-positive result. |
| Crime scene investigators (CSI's) must inspect any | | | | Nitrogen-containing compounds such as fertilizer, |
| suspect's face, hands, and clothing and get samples. | | | | tobacco, cosmetics, and urine can also interact with |
| The archaic paraffin test, where melted wax is used | | | | the amino group of diphenylamine to contribute to |
| to recover residues from the firearm user's hands, is | | | | this false-positive. Therefore, it is up to the forensic |
| no longer used anymore. Instead, CSI's obtain GSR | | | | scientist to confirm the results with more definitive |
| residue by swabbing the suspect's hands, arms, and | | | | testing. |
| clothing with a moist Q-tip or filter paper. | | | | |