Psarreas, Tricia. Crime Scene Investigations:

Psarreas, Tricia. Crime scene investigations: Firearm evidence, Helium.com. Retrieved February 12, 2010 from http://www.helium.com/items/1481011-crime-scene-investigation-firearm-evidence

This article provides a general overview of the types of firearm evidence that can be used at a crime scene to help identify the gun (and hopefully the shooter). It begins by discussing how bullet matching takes place, describing how the markings in the barrel of each gun is different, so forensics experts can use look at the markings on the bullet to help determine whether or not a certain gun was used in the shooting. The author then proceeds to discuss how to use discarded cartridge cases as an identification method, by comparing the markings to various parts of the weapon, such as the firing pin, the breechblock, the firing chamber, the extractor, and the ejector marks. The next method discussed in this article is automated firearm search systems. These are computer databases that help crime labs link information together that can help solve the crime. The final method of obtaining firearm evidence that is discussed in the article is serial number restoration, which is used when someone has attempted to scratch off the serial numbers of a gun.

"Firearms Evidence Collection Procedures" Physical Evidence Bulletin, California Department of Justice, Bureau of Forensic Services, Retrieved February 12, 2010 from http://www.cci.ca.gov/Reference/peb/peb12.pdf

This is newsletter put out by the California Department of Justice, Bureau of Forensic Services that is designed to give crime scene investigators and overview of how to collect firearm evidence safely and accurately. This article recognizes that there are many firearm evidence collecting techniques other than just the standard bullet and cartridge matching. Other types of firearm evidence include: "distance determinations based on powder residue or shot spread; examination of firearms for functioning or modification; sequence of shots fired and trajectories; list of possible weapons used; serial number restoration and ownership tracing." The article emphasizes that safety is always the first priority when handling any sort of firearm. The second priority is not tainting the evidence. Therefore, step-by-step procedures are given to achieve both of these goals. For example, it is suggested that investigators should mark the original position of the cylinder before moving it, and that the weapon should be delivered to the lab in person as opposed to trusting a third party with it.

Schehl, Sally a. "Firearms and Toolmarks in the FBI Laboratory Part 3," Forensic Science Communications vol. 2 April 2000.

This article begins by listing every possible piece of equipment that could be tested when obtaining firearm evidence. Everything from rifles and pistols, to accessories like silencers and holsters, to bullets and wads are included in the list. The author then goes on to describe the different types of tests that may be used after the initial examination. These include trigger pull tests which measure the amount of force it takes to pull the trigger, and gunshot residue tests which look for gunpowder residue on a suspect's hands. The last part of the article discusses how important the firearms and toolkit units are to the FBI. The author talks about several investigations, including the assassinations of John F. Kennedy and Martin Luther King, jr., that have been aided by firearm evidence teams.

Evidence Submission Guideline #10: Firearms Evidence. Indianapolis-Marion County Forensic Services Agency Retrieved February 12, 2010 from http://www.indygov.org/eGov/County/FSA/Documents/Firearms.pdf

This documents provides the guidelines for investigators submitting firearm evidence in Indianapolis-Marion County. It has guidelines for every step of the evidence-collecting process. For example, photos that are taken must have a scale (such as a ruler next to it) to show size. In the firearm itself, the investigator is asked to include certain information in their notes such as the appearance of the cylinder, the marks made on each side of the top strap, and diagrams showing the direction of the rotation. There are also directions on how to package cartridges (both fired and unfired) such as making sure they are surrounded by cotton or a similar soft material, that the package is sealed tightly and that the correct information is included on the label. Most of the guidelines are very specific. But there are also some more obvious guidelines, such as that the firearm should be given to the lab unloaded and that weapons should be handled with care.