Bullet and toolmark analysis
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Bullet and Toolmark Analysis
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Ms. Mouser's lecture on Bullet and Toolmark Analysis for Fall 2011 Forensic Science class.
Transcript of Bullet and toolmark analysis
Bullet and Toolmark Analysis
Bullet and Toolmark AnalysisEverything you always wanted to know, but were afraid to ask . . .
Firearms Identification
Firearms Identification
A discipline mainly concerned with
determining whether a bullet was fired from a
particular weapon.
Firearms Identification
A discipline mainly concerned with determining whether a bullet was fired from a particular weapon.
Firearms Examiner
A gun.
Bullets in shells.
Gun Class Characteristics that you
can get off a bullet:
Gun Class Characteristics that you can get off of a bullet:# of grooves and lands
Gun Class Characteristics that you
can get off a bullet:# of grooves and lands
Direction of twist
Gun Class Characteristics that you
can get off a bullet:# of grooves and lands
Direction of twist
Caliber
Enough for a positive ID of a weapon?
Enough for a positive ID of a weapon?
Nope.
Comparison Microscope
Striation comparison
Firing Pin Impression
Breechblock impression
Obstacles to firearms identification
Obstacles to firearms identification
Obstacles to firearms identification
Shotguns are different.
See any rifling?
Some shotgun cartridges.
Shotgun cartridge.
Shotgun pellets.
Shotgun pellets.
Shotgun slug.
Shotgun slugs.
Shotgun firing.
CODIS, IAFIS . . . meet:
CODIS, AFIS . . . meet:
What else Firearms Examiners do
What else Firearms Examiners doThey do more!
Distance Determination!
Bang.
Contact
Stellate:
IR light can help visualize GSR on busy fabric:
Nitrite Residue patterns from known distances.
Firearms Do’s and Don’t’s
___ pick up a firearm by sticking something (like a pencil) into the barrel
and then lifting it.
DON’T pick up a firearm by sticking something (like a pencil) into the barrel and then lifting
it.
___ pick up a firearm by the checkered grip.
DO pick up a firearm by the checkered grip.
___ unload a firearm before you send it to
the lab.
DO unload a firearm before you send it to
the lab.
___ record the safety and hammer positions of a suspect weapon before unloading it.
DO record the safety and hammer positions of a suspect weapon before unloading it.
___ mark evidence bullets with your initials
on the side of the bullet.
DON’T mark evidence bullets with your initials
on the side of the bullet.
