Firearms Processing

January 12

2013

This paper concerns some of the safety practices of processing firearms.

Safety During Firearms Processing

 

 

Firearms Processing

If you are not familiar with a weapon that you discovered at a crime scene, you should consult somebody that is familiar with it.  When rendering a firearm safe, you need to take special care not to point the weapon at anyone.  While pointing the muzzle down and away from everyone, unload the weapon to render it safe.  While doing this, you need to prevent making contact with any part of the weapon which may contain latent fingerprints.  After safely unloading the weapon, place a zip tie through the magazine port and the action to prevent the weapon from functioning.  On a revolver, place a zip tie through the cylinder after safely unloading it.  (Young, 2011, p. 263)

            When processing firearms evidence we need not forget about ammunition.  On a semi-automatic firearm, after removing the magazine and placing in a paper bag, we need to eject the round from the chamber and place in a separate container.  It is important to keep separate because the chamber may have inflicted certain marks which can possibly be used as evidence.  On a revolver, the round directly in front of the chamber is labeled as number 1; the rounds then are removed in a clockwise pattern, with each sequential cartridge numbered accordingly.  Long guns such as rifles and shotguns are no exception to the firearms safety rule.  (Young, 2011, pp. 263-267)

            Rifles like pistols make striations on the projectile caused by the lands and grooves in the barrel as well as any imperfections in the barrel.  Shotguns are a little different in that they do not contain rifling in the barrel.  Here we concentrate more on the casings to give us information about the firearm.  We look for a firing pin indention in the base of the shell; this can be a signature of the weapon.  (Young, 2011, pp. 267-271)

            As far as collecting firearms evidence; any particle left by the firearm is to be collected and labeled separately.   It is important for measurements and photographs be taken of all evidence.  If a bullet is lodged in a surface, the entire surrounding surface should be removed and transported as evidence.  When collection and processing of the evidence is done properly; it can help us link an expended projectile to a specific firearm.  This in turn allows us to connect the firearm to an individual.  It may also allow us to connect a specific firearm to an unrelated shooting.  The way this is done is to make a control shot with the firearm, then with a comparison microscope, make comparisons between the evidence projectile and the control projectile.  No two firearms make the exact striations on a projectile; therefore an expended projectile can be linked to a specific firearm.  (Young, 2011, p. 271)

            Not only do we compare projectiles, but spent cartridges can be compared and analyzed also.  The extractor or ejector can make identifying markings on the casings as well as the impression made by the firing pin.  (Young, 2011, p. 274)

            Other evidence we can collect from firearms is residue left on surrounding areas from unburned powder.  We can also find latent prints and DNA left on the firearm from the user.  (Young, 2011, pp. 274-277)

           

 

 

 

References

Young, T. &. (2011). Crime Scene Investigations: The forensic technician's field manual. Boston: Prentice Hall.