190 likes | 412 Views
Ballistics: Introduction. Ballistic evidence helps explain:. Long Guns and Handguns. Long guns Handguns Automatic and Semi-automatic. Firearms and Rifling. Bullets, Cartridges, and Calibers. Cartridge— Semi has 10 cartridges in a magazine (clip)
E N D
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 • Cartridge— • 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 • 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? Forensic Science: Fundamentals & Investigations, Chapter 17
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 canfigure 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