Firearms, Explosives Arson – Stephen
1. How are spent casings recovered from a crime scene examined? Do they possess individual or class characteristics?
First, let’s explain what casings are before discussing gathering evidence of a crime scene. In order to understand firearms, we must first understand what casings are and how they are related to firearms. Casings are the part of ammunition that you see on the actual bullet itself. The casing is what holds and binds the bullet together until it is fired out of a weapon or disassembled. Within the casing, you will find multiple chemicals that will be necessary to make a firearm operation. You will find things such as primer, gunpowder, and the bullet (9 mm, 5.56 mm, 7.56mm, etc.) depending on what type of firearm is utilized. Once the firing pin hits the back of the case shell within the firearm, the primer that is located within the casing is the spark that sets off the gunpowder in a firearm that will set the bullet in a particular direction/trajectory. Gunpowder itself is what causes the bullet or pellets to travel on its “trajectory”.
In general, when a firearm fires a bullet, the case shell in which the bullet is fired is dispatched onto the ground. In other words, for example, another term that is used is called “brass”, which contains nothing but the outer shell of ammunition. The dispatched “brass” or “casing” can be recovered in the area in which the firearm was used. Unless recovered by the user, the casing is what will be left behind. When an officer recovers a casing, he/she can determine what type of firearm was being used when the user fired the weapon. It is all measured or may have a specific identification number to determine what type of bullet is used, like a 9 mm casing shell. They will be able to narrow down as to what type of hand firearm was used specifically for that 9 mm casing shell.
2. Describe methods utilized at a crime scene to detect accelerants and explosive material.
Regarding explosive material, explosives should be handled by certified professionals who are trained by explosive technicians. These certified personnel are trained to detect specific components that make the blueprint of an explosive device. When an explosive ignites, it leaves behind debris from what made the bomb functional. Law enforcement will collect what is left behind and return it to their lab for further testing. Accelerants are the material that aids in spreading fire. Normally, accelerants are collected based on the debris that is left from the built explosive device.
Reference
What are the Basic Parts of Ammunition. Berry’s, Posted in Blogs. July 28, 2022. https://www.berrysmfg.com/blog/what-are-the-basic-parts-of-ammunition#:~:text=The%20casing%20is%20what%20holds,are%20created%20using%20polymer%20plastics.
Firearms forensics. David Spraggs. February 2010. https://www.atf.gov/resource-center/docs/020110-police-magazine-firearms-forensicspdf/download
Evidence Collection and Laboratory Analysis. Inter Fire Online. Copyright © 2024 All Rights Reserved. https://www.interfire.org/res_file/lab.asp
