Ballistics: Introduction Ballistic evidence helps explain: Ref: Forensic Science: Fundamentals & Investigations, Chapter 17 Bertino

Long Guns and Handguns Long guns Handguns Automatic and Semi-automatic Forensic Science: Fundamentals & Investigations, Chapter 17

Firearms and Rifling Forensic Science: Fundamentals & Investigations, Chapter 17

Bullets, Cartridges, and Calibers Semi has 10 cartridges in a magazine (clip) The bullet, usually of metal, is out front with the cartridge, holding the primer and propellant powders, behind. Forensic Science: Fundamentals & Investigations, Chapter 17

How a Firearm Works Forensic Science: Fundamentals & Investigations, Chapter 17

How a Firearm Works Forensic Science: Fundamentals & Investigations, Chapter 17

Caliber of the Cartridge Caliber—a measure of the diameter of the cartridge (stamped on headstamp on the bottom of the cartridge casing) In hundredths of an inch Common calibers include .22, .25, .357, .38, .44, and .45 Why should the caliber of ammunition match the firearm that shoots it? If they do not match, what could go wrong? Forensic Science: Fundamentals & Investigations, Chapter 17

The Study of Bullets and Cartridge Casings Forensic Science: Fundamentals & Investigations, Chapter 17 How is each fired bullet marked? What is the procedure to match a spent bullet to the firearm that shot it? What makes up a test-firing, and why is it done?

Marks on the Spent Cartridge Casings Firing pin marks Breechblock marks Extractor marks Ejector marks Forensic Science: Fundamentals & Investigations, Chapter 17

Gunshot Residues Gunshot Residues (GSR) Forensic Science: Fundamentals & Investigations, Chapter 17

Trajectory Two reference points are needed to define the trajectory Investigators can figure the shooter discharged the firearm somewhere along that line Forensic Science: Fundamentals & Investigations, Chapter 17

Trajectory Reference points can be bullet holes in objects or victims An entry point and exit point on a victim Gunshot residue or spent cartridge casings Lasers can trace a straight-line path to determine the position of the shooter Forensic Science: Fundamentals & Investigations, Chapter 17

Determining the Location of the Shooter Building is 60 feet away along the horizon line Bullet hole is 4 feet above the ground Where is the shooter located? Forensic Science: Fundamentals & Investigations, Chapter 17

Triangulation B is where the shooter is located; find the length of BC The Abc triangle has the same proportions as the ABC triangle Forensic Science: Fundamentals & Investigations, Chapter 17

Triangulation Using Pythagorean’s theorem AB2 = AC2 + BC2 Forensic Science: Fundamentals & Investigations, Chapter 17

Bullet Wounds Why do entrance wounds tend to be smaller than exit wounds? If the bullet penetrates clothing, what can fibers embedded in the wound indicate? Where is gunshot residue usually found? If the gun is fired with the muzzle touching the victim’s skin, what telltale mark may show up? Will larger or will smaller caliber bullets tend to lodge within the body rather than passing through? Why? Forensic Science: Fundamentals & Investigations, Chapter 17 Kennedy assassination recreation http://www.youtube.com/watch?v=R5JDhi4URds