Tennessee Bureau of Investigation Tennessee Bureau of Investigation Crime Laboratory Crime Laboratory Firearms Identification Unit Firearms Identification Unit Crime Laboratory Crime Laboratory Firearms Identification Unit Firearms Identification Unit
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Tennessee Bureau of InvestigationTennessee Bureau of InvestigationCrime LaboratoryCrime Laboratory
Firearms Identification UnitFirearms Identification Unit
Crime LaboratoryCrime Laboratory
Firearms Identification UnitFirearms Identification Unit
Firearms IdentificationFirearms Identification
• What Is Firearms Identification?
A di i li f F i S i hi hA discipline of Forensic Science which has as its primary concern to determine if b ll id hif a bullet, cartridge case, or other ammunition component was fired in a
i l fi h l i f llparticular firearm to the exclusion of all others.
Duties of TBI Firearm Identification UnitDuties of TBI Firearm Identification Unit
• Identification of fired bullets, cartridge cases, shotshell cases, and other ammunition components to their source.p
• Entry of fired cartridge cases into the IBIS Imaging System
• Toolmark Examinations
• Obliterated Serial Number Restoration
• Muzzle-to-Garment Distance Determination
• Crime Scene Technical Assistance• Crime Scene Technical Assistance
• Provide Expert Court Testimony as to the results of examinations.
• Bureau Armorer’s for all Bureau Issued Firearms
Requirements for the JobRequirements for the Job
• Must have a bachelor's degree from an accredited college or university in the natural or physical sciencescollege or university in the natural or physical sciences
• Must have a minimum of 24 semester hours in chemistryMust have a minimum of 24 semester hours in chemistry
Bullet Class CharacteristicsBullet Class Characteristics
• How is Firearms Identification possible when dealing with fired bullets?
When firearms are manufactured, they receive what is known as “rifling.”
Rifling is a manufacturing process that cuts a series of lands and grooves into the barrel of the firearmlands and grooves into the barrel of the firearm.
The rifling is predetermined at the factory alsoThe rifling is predetermined at the factory, also known as “class characteristics”.
• When a bullet is fired through the barrel of a firearm:
The bullet expands into the lands and grooves
Th “ l h t i ti ” i d t th ftThe “class characteristics” are impressed onto the softer surface of the bullet.
i f i (i i i i i )The random imperfections (individual characteristics)present in the barrel are also transferred to the softer surface of the bullet.
The random imperfections are reproduced to form the “mechanical fingerprint” that makes that particular ec a ca ge p t t at a es t at pa t cu afirearm unique