What is Frye's reagent used for in forensic investigations?

Frye's reagent is specifically used in forensic investigations for the recovery of serial numbers from firearms. This compound acts as a developing agent that can reveal obliterated or defaced serial numbers on guns, which is critical in identifying weapons that may have been tampered with or altered to conceal their origins. When applied to an affected area, Frye's reagent reacts with the metallic residues and can enhance the visual contrast of the serial numbers, allowing investigators to record them and potentially link the firearm to a specific crime or owner.

The other options, while relevant to firearms and forensic science, do not directly involve Frye's reagent. For example, enhancing bullet tracking often relies on different ballistic techniques, analyzing gunshot residue is typically performed using methods like atomic absorption spectroscopy or scanning electron microscopy, and identifying the chemical composition of gunpowder would involve chemical analysis rather than the application of Frye's reagent. Each of these processes employs distinct methods tailored to their specific investigative needs, underscoring the unique application of Frye's reagent in revealing serial numbers on firearms.