1. Firearms

2. Firearms: Oscar Pistorius
February 14, 2013
1:30am—neighbors of Oscar Pistorius, Paralympic champion and Olympic runner, call police for a noise disturbance
Pistorius shoots his girlfriend Reeva Steenkamp
Acknowledges that he shot Steenkamp four times, but said he mistook her for a possible intruder
Spends the night at the Boschkop police station

3. FireArms: Oscar Pistorius

4. Firearms: Oscar Pistorius

5. Firearms: Oscar Pistorius
A case of premeditated murder is opened against Pistorius
February 19—Pistorius insists he did not plan to kill Steenkamp and cries uncontrollably and states the loved her
February 22—Pistorius posts bail and the case is postponed to June 4

6. Firearms: Oscar Pistorius
March 3, 2014—Trial starts
Pistorius is also charged with illegal possession of ammunition and firing a gun in a public space
First witness (neighbor) testifies to hearing “blood-curdling” screams before the sound of gunshots on the night Pistorius killed Steenkamp

7. Firearms: Oscar Pistorius
March 24—Whatsapp messages between Pistorius and Steenkamp are read
“I’m scared of you sometimes and how you snap at me and how you will react to me”
April 7—Pistorius takes the stand
Begins with an apology “There hasn’t been a moment since this tragedy happened that I haven’t thought about your family”
Pistorius is cross examined for 7 days
Forced to look at Steenkamp’s head wound, re-read Valentine’s Day cards Steenkamp sent him, etc.

8. Firearms: Oscar Pistorius
September 11, 2014—Pistorius is found guilty of culpable homicide. Found not guilty of murder and granted bail until his sentencing

9. Firearms Forensic analysis is vital to solve a crime that uses a gun
In 2018, there were about 14,600 gun-related deaths in the US (not including suicides)
The vast majority of
U.S. homicides involve
guns. And they are more
powerful than ever.
Lansing State Journal, July 2007

10. A Quick History
Almost every gun is based on the same simple concept: You apply explosive pressure behind a projectile to launch it down a barrel
The earliest & simplest application of this idea is the cannon
The 1st handheld guns were essentially mini-cannons; you loaded some gunpowder & a steel ball & lit a fuse

11. A Quick History

12. A Quick History (cont.)
War typically resulted in the need for improved weapons technology
In the late 1800s, the revolver quickly became popular due to its size & quick loading
It only had to be reloaded every 5-6 shots instead of after each shot

13. A Quick History(cont.)
Handguns reigned supreme for the past 200 years &, to this day, remain the most popular & readily available firearm

14. Types of Firearms Handguns Long/Shoulder Guns Mounted guns
Pistols, semiautomatic handguns, machine pistols, revolvers
Long/Shoulder Guns
Rifles, shotguns
Mounted guns
Large machine guns mounted on an aircraft, tank, etc.

15. Ammunition Components:
Cartridge case (container that holds all components together)
Primer (explosive chemical compound that ignites the propellant when struck by a firing pin)
Propellant (often gunpowder; burns rapidly and converts to an expanding gas)
Projectile (bullet; object expelled from the barrel)

16. Ammunition

17. Firearms Identification
Firearms is often confused with the term ballistics
Ballistics is the study of a projectile in motion
Identification of firearms is based upon this basic idea: A harder object marks a softer one & imparts/transfers its microscopic irregularities to that object

18. Pulling the Trigger Pulling the trigger releases the firing pin…
The firing pin strikes the primer…
The primer ignites the gun powder…
The powder generates gas that propels the bullet forward through the barrel & ejects the spent cartridge case

19. Firearm Evidence Individual: Striae Firing pin marks Breech marks
Extractor marks
Ejector marks
Chamber marks
Class:
Bullet type
Bullet caliber
Bullet weight
Lands & grooves
Rifiling
Cartridge case
Head stamp

20. Bullet Caliber Caliber is the diameter of the gun barrel
Caliber is recorded 2 ways:
Hundreths of an inch (.22 & .38)
Millimeters (9mm)

21. Bullet Comparisons
Each gun leaves distinct markings on a bullet passing through it
A gun barrel is made from a solid bar of steel that has been holloed out
The drill leaves microscopic marks on the barrel’s inner surface
Gun manufacturers also add spiral grooves to the barrel. This is known as rifiling
As a spinning bullet passes through the barrel, it is marked by these grooves

23. Firearm Evidence
Breech marks—left when the shell is forced back against the breech of the gun
Firing pin marks—impression left unique to the gun’s firing pin on the back of the cartridge
Head stamp—tells who manufactured the case
Extractor & Ejector marks—extracting pin and ejector leave marks on the shell casing when throwing the spent shell from the chamber

24. Gunshot Residue (GSR) When a weapon is fired:
Primer and propellant particles blow back toward the shooter
Combustion products, unburned propellant, and particles of lead follow the bullet, spreading out with distance

25. Contact GSW
Since the barrel contacts the skin, the gases released by the fired round go into the subcutaneous tissue & cause the star-shaped laceration
Entrance wound

26. Abrasion Ring
Formed when the force of the gases entering below the skin blow the skin back against the muzzle of the gun

27. Exit Wounds
Exit wounds vary in size and shape because the bullet can be deformed in its transit through the body
There may be no exit wound at all if the bullet’s energy is absorbed by the tissue. Some bullets are designed to deform so that all their energy will be converted to tissue damage and not exit

28. Firearms Evidence Collection
Make sure it is unloaded!!!!
Revolvers
Indicate location of fired & unfired ammunition
Automatics
Check magazine for number of rounds
Fingerprint magazine
Place ID tag on trigger guard
Ammunition
Package in pill box or envelope
Wrap in tissue to protect