What is one of the first steps in examining gunshot residue?

Identifying the type of gun used is crucial in the examination of gunshot residue because it lays foundational knowledge for understanding the crime scene dynamics and the evidence gathered. This step involves recognizing the firearm's characteristics, which can severely influence both the type of residue present and its distribution. Different firearms produce varying amounts and types of gunshot residue due to differences in ammunition and firing mechanisms. This knowledge aids in narrowing down suspects, as gunshot residue can be a direct indicator of who fired a weapon or has been in close proximity to a discharged firearm.

In contrast, while detecting caliber size, tracing the bullet’s path, and determining environmental conditions are important aspects of a comprehensive firearm investigation, they typically follow the identification of the gun type. Caliber size helps match projectiles to specific firearms but is secondary to knowing what types of firearms are involved. Tracing the bullet’s path helps establish the scenario of the shooting but is applied after residues are analyzed. Environmental conditions could affect residue dispersion but are not part of the primary investigative steps focused on linking residues to a specific firearm.