What does a Gunshot Residue (GSR) test assess, and what are its limitations?

What does a Gunshot Residue (GSR) test assess, and what are its limitations?

• A. Tests for residue from a discharged firearm; positive result supports firing but is not conclusive of shooter identity and can reflect secondary transfer
• B. Tests for residue from a discharged firearm; positive result confirms shooter identity
• C. Tests for gunpowder residues from a suspect's hands; negative result proves innocence
• D. Tests for explosive residues at a scene; results are always definitive

Answer: (A)

Gunshot residue testing looks for primer-derived material left on a person or object after a firearm is discharged. A positive result can indicate that the person may have fired a gun or handled a recently fired weapon, or that they were exposed to residue through proximity or secondary transfer. But this finding does not prove who fired the weapon. Residues can transfer from one person to another, or contaminate a scene in various ways, so a positive result is supportive but not conclusive for shooter identity. Conversely, a negative result does not rule out firing, because residue can be wiped away, degraded over time, or may not transfer depending on the ammunition or handling conditions. In short, GSR testing provides useful contextual information but must be interpreted with other evidence and, when possible, corroborated with more specific analytical methods.

Gunshot residue testing looks for primer-derived material left on a person or object after a firearm is discharged. A positive result can indicate that the person may have fired a gun or handled a recently fired weapon, or that they were exposed to residue through proximity or secondary transfer. But this finding does not prove who fired the weapon. Residues can transfer from one person to another, or contaminate a scene in various ways, so a positive result is supportive but not conclusive for shooter identity. Conversely, a negative result does not rule out firing, because residue can be wiped away, degraded over time, or may not transfer depending on the ammunition or handling conditions. In short, GSR testing provides useful contextual information but must be interpreted with other evidence and, when possible, corroborated with more specific analytical methods.