What is the optimal method for detecting gunshot residue on a suspect's hands?

The optimal method for detecting gunshot residue (GSR) on a suspect's hands involves swabbing with a cotton swab moistened with nitric acid. This approach is effective because nitric acid serves to dissolve various metal particles, including lead, barium, and antimony—key components commonly found in GSR. By using an acidic solution, it enhances the likelihood of extracting these residues from the surface of the skin, making them more detectable during subsequent analysis.

This method stands out due to its ability to chemically react with the GSR and facilitate the collection of particles that might otherwise be challenging to capture with dry or non-reactive methods.

In contrast, other methods such as simply using a cotton swab moistened with water may not effectively capture GSR, as water alone does not dissolve the metal residues and could potentially lead to the loss of evidence. Wiping with a cloth could risk smearing the residues or removing them entirely from the hands, compromising the evidence. Using a brush might not be as effective in capturing the fine particles of GSR, as the technique relies on physical brushing that may not gather all the relevant traces effectively.

Therefore, the use of a cotton swab moistened with nitric acid is the most