fs ch 8 online
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Firearms, Tool Marks, and Other Impressions
Chapter 8
Firearms
Forensic ScienceRichard Saferstein
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Handguns Single-shot
Revolvers
Semi-automatic
Automatic
Forensic ScienceRichard Saferstein
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Revolver
The live rounds are placed into the cylinder
Forensic ScienceRichard Saferstein
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Revolver
A loaded revolver
Forensic ScienceRichard Saferstein
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Revolver
Some guns just command your attention
Forensic ScienceRichard Saferstein
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Revolver
Loading a revolver
Forensic ScienceRichard Saferstein
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revolvers
Many types
Forensic ScienceRichard Saferstein
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Revolvers
This one is too pretty to shoot.
Forensic ScienceRichard Saferstein
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Semi-automatics
Utilize a magazine and internal feeding system
Forensic ScienceRichard Saferstein
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Semi-automatics
Various models
Forensic ScienceRichard Saferstein
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Semi-Automatics
Internal workings of a semi-auto
Forensic ScienceRichard Saferstein
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Semi-automtaics
Stove pipe: The ejected shell casing is jammed in the ejector port
Forensic ScienceRichard Saferstein
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Long Guns Long guns:-single-shot/repeating/semi-automatic/
automatic
Shotguns-smooth bore
Rifles
Forensic ScienceRichard Saferstein
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Rifles
Bolt action, pump action and lever action
Forensic ScienceRichard Saferstein
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Shotguns
Wide varieties
Forensic ScienceRichard Saferstein
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Shot gun
Another pretty gun
Forensic ScienceRichard Saferstein
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Introduction Structural variations
Bullet to gun Scratch/abrasion to tool tire track to automobile
Individualization!
Forensic ScienceRichard Saferstein
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Gun Barrel Markings
steel bar hollowed by drilling
-drill marks: unique
-Bullet picks up marks/unique
Forensic ScienceRichard Saferstein
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Gun Barrel MarkingsMuskets/pistols: smooth barrels
Rifling: Spin on bullet
LANDS & GROOVES:Lands: Surfaces between grooves
Grooves: Spiral cuts in barrel
Forensic ScienceRichard Saferstein
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Lands and grooves
Don’t try this at home!
Forensic ScienceRichard Saferstein
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Forensic ScienceRichard Saferstein
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Gun Barrel Markings Caliber: barrel diameter
Manufacturing rifling process: -class characteristics -consistent
Forensic ScienceRichard Saferstein
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Striations Striations:
-manufacturing
bullets
-Individual characteristics
Forensic ScienceRichard Saferstein
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Bullet
Note the striations on the fired bullet. These are unique to the gun that fired it.
Forensic ScienceRichard Saferstein
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Ammunition
CARTRIDGE/ROUND:
Casing
Bullet
Powder
Primer
Forensic ScienceRichard Saferstein
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Ammo
Various types of ammunition
Forensic ScienceRichard Saferstein
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Rifle cartridge
Internal view
Forensic ScienceRichard Saferstein
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Cartridge
Internal view
Forensic ScienceRichard Saferstein
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Rifle cartridges
Various calibers
Forensic ScienceRichard Saferstein
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Firearm Examination
Lands/Grooves/Twist: -start of exam
Match
OR
Eliminate
Forensic ScienceRichard Saferstein
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The Comparison MicroscopeFor + match:
-Lands/grooves identical widths
-longitudinal striations coincide
Forensic ScienceRichard Saferstein
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Comparison Microscope
Using a comparison microscope an examiner can view both bullets at once
Forensic ScienceRichard Saferstein
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Examination
This is an example of two fired bullets. The striations are identical.
Forensic ScienceRichard Saferstein
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Exams
Another example of matching striations
Forensic ScienceRichard Saferstein
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Shotguns-smooth barrel
-Shot: pellets
-gauge: Diameter of barrel
Forensic ScienceRichard Saferstein
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Shot gun shell
Forensic ScienceRichard Saferstein
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Firing a Weapon1. Trigger pull
2. Hammer falls
3. Firing pin strikes primer
4. Gases ignite/expand
5. bullet out barrel/striations
Forensic ScienceRichard Saferstein
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Firing a Weapon
Revolver:
-cylinder advances
-shell casings remain in weapon
Forensic ScienceRichard Saferstein
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Firing a Weapon
Semi-auto:
Ejector: Casing out
Extractor: Next round
Breech lock: Back stop
Forensic ScienceRichard Saferstein
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Firing a weapon
The hammer falls, hits the firing pin and the powder ignites sending the bullet down and out the barrel. There are a lot of gases and powders that are projected with bullet.
Forensic ScienceRichard Saferstein
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Cartridge/Shell Case Comparison -ejector
-extractor
-breech lock
-magazine
Forensic ScienceRichard Saferstein
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Head stamp
The firing pin leaves a unique mark on the primer.
Forensic ScienceRichard Saferstein
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Yikes
Crime scene investigators nightmare. Each one of these casings needs to be marked, photographed, collected and packaged separately.
Forensic ScienceRichard Saferstein
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Head stamp
Microscopic comparison of firing pin marks
Forensic ScienceRichard Saferstein
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Computerized ImagingNational Integrated Ballistics Information
Network, (NIBIN):
bullets Casings firearms
Firearms examiners v. Ballistics!!!!!
Forensic ScienceRichard Saferstein
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Gunpowder Residue
Muzzle close: Powder on target
Powder patterns: Estimate distance.
Forensic ScienceRichard Saferstein
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Powder and residue being projected.
Forensic ScienceRichard Saferstein
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Really being projected.
Forensic ScienceRichard Saferstein
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Gunpowder ResidueStellate wound: close contact Star shaped Rim of lead
Halo: 12-18 inches
Stippling/Tattooing: 2-3 feet Powder depositBAD PICTURES COMING UP!!!!!!!!!!!!
Forensic ScienceRichard Saferstein
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Close contact-Stellate wound
Forensic ScienceRichard Saferstein
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Close contact-Stellate wound
Forensic ScienceRichard Saferstein
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Impression of gun against skin
Forensic ScienceRichard Saferstein
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Impression of gun against skin
Forensic ScienceRichard Saferstein
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Impression of gun against skin
Forensic ScienceRichard Saferstein
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Stippling
Forensic ScienceRichard Saferstein
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Forensic ScienceRichard Saferstein
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Example of stippling
Forensic ScienceRichard Saferstein
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Stippling
Forensic ScienceRichard Saferstein
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Stippling
Forensic ScienceRichard Saferstein
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Forensic ScienceRichard Saferstein
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Gunshot wound no stippling
Forensic ScienceRichard Saferstein
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Gunshot wound entrance
Forensic ScienceRichard Saferstein
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Gunshot wound exit
Forensic ScienceRichard Saferstein
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Stellate wound to skull
Forensic ScienceRichard Saferstein
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GSR on HandsFired weapon:
GSR forward
GSR Back towards shooter
Extremely fragile!
Forensic ScienceRichard Saferstein
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GSR
Bang! That’s a lot of powder
Forensic ScienceRichard Saferstein
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GSR Test
This is where you would expect to find GSR and where you swab for it
Forensic ScienceRichard Saferstein
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GSR
Under a microscope
Forensic ScienceRichard Saferstein
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Serial Numbers
Criminals obscure:
Permanent on surface
Chemical etching
Forensic ScienceRichard Saferstein
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Serial restoration kit
Combines acids and electricity to restore serial numbers
Forensic ScienceRichard Saferstein
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Firearm Evidence CollectionHow do you collect firearms?
Checkered grips
Unload
Record cylinder location
Check for shells/live rounds
Mark/chain of custody
Forensic ScienceRichard Saferstein
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Firearm Evidence CollectionBullets: Initials
Striation awareness Cotton/pill bottle
Shell casings: Initials
Shotgun shells: Initials
Forensic ScienceRichard Saferstein
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Tool MarksImpression/cut/gouge/abrasion
Examination:Class characteristics Size/shape
Individual characteristics Minute imperfections
Forensic ScienceRichard Saferstein
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Tool MarksComparison microscope
Collecting tool marks:
Entire/part of object
Never fit tool into impression!!!!
Forensic ScienceRichard Saferstein
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Tool marks
Microscopic view
Forensic ScienceRichard Saferstein
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Forensic ScienceRichard Saferstein
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Other ImpressionsShoe/Tire impressions
Collecting:
Photographs (scale)
Recoverable item to lab
Alternative: Cast/lift
Forensic ScienceRichard Saferstein
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Impressions
Footwear
Forensic ScienceRichard Saferstein
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Impressions
Impressions compared to suspect’s shoe
Forensic ScienceRichard Saferstein
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Impressions
Comparison in progress
Forensic ScienceRichard Saferstein
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Impressions
Casting footwear impressions in dirt
Forensic ScienceRichard Saferstein
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Impression
Wax spray is used to preserve footwear impressions in snow
Forensic ScienceRichard Saferstein
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Impressions
Tire impressions
Forensic ScienceRichard Saferstein
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Points of ComparisonNumber of points?
New Computer technology
Bite Marks: Food Skin Individual characteristicsPEOPLE SLIDES COMIN UP!!! 4TH ONE IS
ACTUAL DEAD PERSON
Forensic ScienceRichard Saferstein
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Bite marks
Child abuse case
Forensic ScienceRichard Saferstein
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Bite marks
Dental stone is used to make a cast impression of bite marks
Forensic ScienceRichard Saferstein
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Bite mark
Tiger Shark bite mark-no suspect in custody