FIREARMS, TOOL MARKS, AND OTHER IMPRESSIONS

1. FIREARMS, TOOL MARKS, AND OTHER IMPRESSIONS Forensic Science - Chapter 16

2. Famous People Killed / Wounded with Guns • Abraham LincolnJohn LennonJohn F. KennedyRobert F. KennedyMartin Luther King Jr.Pope John Paul llMohandas GhandiFranz FerdinandMalcolm XBob MarleyRonald ReaganTheodore Roosevelt50 CentThe Notorious B.I.G.Tupac ShakurSean Taylor

3. How many People Die by Guns? • Guns were used in the USA in 11,422 homicides and 19,392 suicides in 2010, according to the CDC. • In Canada where regular citizens are not allowed to have guns the average is 183 deaths per year. • Interesting Gun Facts: Web site link

4. THE JFK ASSASSINATION • On November 22,1963 the President of the United States, John F. Kennedy was shot and killed on the streets of Dallas. The assassin was identified as Lee Harvey Oswald. video

5. Faces of the Not Famous Gone due to Guns • Sandy Hook Elementary

6. Columbine Colorado

7. Virginia Tech / Aurora Colorado

8. Introduction • Structural variations and irregularities caused by scratches, nicks, breaks, and wear may permit the criminalist to relate: • A bullet to a gun • A scratch or abrasion mark to a single tool • A tire track to a particular automobile • Individualization, a goal of in all areas of criminalistics, frequently becomes an attainable reality in firearm and tool mark examination.

9. Different Tools / Guns Tools of all types will leave marks that can be traced back to a source in criminal forensics.

10. Gun Barrel Markings • The inner surface of the barrel of a gun leaves its markings on a bullet passing through it. • These markings are peculiar to each gun. • The gun barrel is produced from a solid bar of steel that has been hollowed out by drilling. • The microscopic drill marks left on the barrel’s inner surface are randomly irregular and serve to impart a uniqueness to each barrel.

11. Father of Ballistics • Calvin Goddard, physician , acquired data from all known gun manufacturers in order to develop a comprehensive database. With his partner, Charles Waite, he catalogued the results of test-firings from every type of handgun made by 12 manufacturers. Waite also invented the comparison microscope. With this instrument, two bullets could be laid adjacent to one another for comparative examination.

12. Ballistic Fingerprinting • Ballistic fingerprinting refers to a set of forensic techniques that rely on marks that firearms leave on bullets to match a bullet to the gun it was fired with.

13. Bullet Recovery Tank • Each gun submitted is test fired and the recovered bullets and cartridge cases are retained for use in further analysis.

14. Recovered Bullets

15. The Bore of Guns

16. Gun Barrel Markings • The manufacture of a barrel also requires impressing its inner surface with spiral grooves, a step known as rifling. • The surfaces of the original bore remaining between the grooves are called lands. • The grooves serve to guide a fired bullet through the barrel, imparting a rapid spin to insure accuracy.

17. Riflings in a Barrell Riflings are the groves that cause a bullet to spin and gain stability for a more accurate shot

18. Lands and Grooves Land Diameter Caliber Groove

19. Gun Barrel Markings • The diameter of the gun barrel, measured between opposite lands, is known as caliber. Most older guns’ calibers are measured in fraction of inches across the islands. So a 45 caliber bullet is 0.45 inches across. Some newer bullets are measured in millimeters. • Once a manufacturer chooses a rifling process, the class characteristics of the weapon’s barrel will remain consistent, each will have the same number of lands and grooves, with the same approximate width and direction of twist.

20. Striations • Striations, which are fine lines found in the interior of the barrel, are impressed into the metal as the negatives of minute imperfections found on the rifling cutter’s surface, or they are produced by minute chips of steel pushed against the barrel’s inner surface by a moving broach cutter. • These striations form the individual characteristics of the barrel.

21. Bullet Striations from the Barrel The striations on the bullet can make identifiable and unique markings that trace it back to a particular firearm.

22. Striations • It is the inner surface of the barrel of a gun that leaves its striation markings on a bullet passing through it. Courtesy of C. Fanning

23. Bullet Examination • No two rifled barrels, even those manufactured in succession, will have identical striation markings. • The number of lands and grooves and their direction of twist are obvious points of comparison during the initial stages of an examination between an evidence bullet and a test-fired bullet. • Any differences in these class characteristics immediately serve to eliminate the possibility that both bullets traveled through the same barrel.

24. The Comparison Microscope • The comparison microscope serves as the single most important tool to a firearms examiner. • Two bullets can be observed and compared simultaneously within the same field of view. • Not only must the lands and grooves of the test and evidence bullet have identical widths, but the longitudinal striations on each must coincide.

25. Comparison of Bullet Marks

26. Bullets become scarred by rifling as they travel down the barrel of a gun

27. Matching Procedure • Fire bullets from a suspected weapon • With the aid of a comparison microscope, compare these “test fires” to the suspected bullets • Striations must be identical for a positive match

28. Two scopes-One Field ComparisonMicroscope

30. HandgunsSemi-automatic Courtesy of C. Fanning Courtesy of C. Fanning Courtesy of C. Fanning

31. Parts of a Semi-auto Handgun

32. Parts of a Semi-auto Pistol

33. 9 mm Glock

34. 25 Auto Bauer Saturday Night Special Semi-automatic Capacity: 10 rounds

35. Parts of a Handgun

36. HandgunsRevolver

37. 6 rounds 38 Special with a speed loader

38. 38 Taurus Ultra-lite 6 Rounds

39. 22 Ruger-Old Western Style Single Action

40. Muzzleloading Rifle

41. Parts of a Bolt Action Rifle

42. Lever Action Rifle • A lever action rifle is one that reloads with the use of a rotating lever handle.

43. Parts of a Semiautomatic Rifle M1 carbine will fire each time you pull the trigger without manually reloading. The shells are held in the vertical clip under the receiver.

44. Modern Smart Guns • The newest rifles have the same computerized targeting systems as military fighter aircraft. Cost: $27k They can shoot targets 10 football fields away. Video

45. Automatic Assault Rifles The most deadly gun that is commonly hand carried by the shooter. It can fire many rounds without reloading; as fast as you can pull the trigger and can be set to fully automatic mode.

46. Machine Guns Fully automatic machine guns can fire up to 1200 bullets per minute. 50 Cal video

47. Rapid Fire Machine Gun Typical cyclic rates of fire are 500–900 RPM for assault rifles, 900-1,200 RPM for submachine guns and machine pistols, and 600-1,200 RPM for machine guns. M134

48. SHOTGUNS • Unlike rifled firearms, a shotgun has a smooth barrel. • Shotguns generally fire small lead balls or pellets that are not impressed with any characteristic markings that can be related back to the weapon.

49. Shotguns • The diameter of the shotgun barrel is expressed by the term gauge. In the lower numbered gauges, it is the number of pellets that are needed to span the internal barrel diameter. • The higher the gauge number, the smaller the barrel’s diameter.

50. Shotgun & Shells