Which statement is true regarding the collection of firearms evidence?

The correct statement about the collection of firearms evidence is that fired shell positions should be noted for revolvers. This is crucial for forensic investigation because the position of spent shell casings can provide significant insights into the sequence of events that occurred during a shooting incident, including the positioning of the shooter and the trajectory of the shots fired.

In revolvers, each spent cartridge remains in the cylinder until it is manually extracted, which means that examining their positions can help determine whether the gun was fired while in a specific position or angle. Collecting this information is vital for reconstruction and can assist law enforcement in understanding the dynamics of the shooting scenario. Additionally, documenting the positions may reveal whether the revolver was fired multiple times in quick succession or if it was manipulated between shots.

Other choices are not accurate in the context of proper evidence collection practices. For instance, marking only the barrel is insufficient for the comprehensive documentation of a firearm, which requires careful handling and consideration of various components. Saying the trigger can be touched freely disregards best practices in evidence preservation and could contaminate the scene. Finally, while handguns can be marked, they should be documented with care, often requiring appropriate markings that do not compromise their integrity or evidentiary value.