How long can gunshot residue (GSR) remain on a person's hands after a weapon is fired?

Gunshot residue (GSR) can indeed remain on a person's hands for an extended period after a weapon has been fired, and the estimate of up to 6 hours is well-supported by forensic studies. This timeframe is influenced by various factors, including environmental conditions, the individual's activities following the shooting, and skin characteristics.

GSR is primarily comprised of microscopic particles that can transfer easily to skin surfaces, clothing, and other items. If a person fires a gun, these particles can be deposited on the hands and may persist for several hours. However, activities such as washing hands, touching surfaces, or sweating can reduce this window significantly.

Understanding this timeframe is crucial for forensic investigators, as it can help establish whether a person was in close proximity to a gun discharge. The potential for GSR to remain detectable for up to 6 hours post-exposure makes it a valuable piece of evidence in criminal investigations.