1. 16-1 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein FIREARMS Forensic Science

2. 16-2 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Famous People Killed / Wounded with Guns Abraham Lincoln John Lennon John F. Kennedy Robert F. Kennedy Martin Luther King Jr. Pope John Paul ll Mahatma Gandhi Malcolm X Bob Marley Ronald Reagan Theodore Roosevelt Sean Taylor

3. 16-3 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein 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

4. 16-4 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearms Identification In a gun-related crime, bullets, cartridge cases, and guns (whether discovered at a crime scene or obtained from a suspect) are important items of evidence that a crime scene investigator must collect for laboratory examination and identification. The laboratory testing of ammunition or guns is known as firearms identification.

5. 16-5 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearms Identification Firearms identification mainly determines whether a bullet or cartridge was fired by a particular weapon, but may also include Knowledge/operation of all types of weapons Estimation of shooting distance Gunshot residue analysis Serial number restoration

6. 16-6 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Background A firearm is a device for accelerating a projectile to a high speed, sending it towards a selected target. The cartridge contains the energy that provides the driving force for the projectile. A cartridge consists of four basic components: the case, powder, projectile, and primer

7. 16-7 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Background Cartridge Components The case is the container for the other three components of a cartridge. Powder consists of small discs, cylinders, or balls of smokeless powder known as cellulose nitrate. The projectile, or bullet, is usually made from lead or copper-coated lead. The primer consists of a shock-sensitive material.

8. 16-8 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Background Rifles, shot guns, and handguns are common firearms that may be involved in a crime. The first step in a firearm examination is to identify the type of firearm used.

9. 16-9 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Types of Firearms Classification by firing mechanism A single shot fires one round then requires manual ejection of the cartridge casing before another round can be fired. A semi-automatic fires one bullet then reloads with a fresh cartridge each time the trigger is pulled and released. An automatic continues to fire projectiles until the trigger is released.

10. 16-10 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Types of Firearms Classification by design & purpose Rifles A firearm designed to be fired from the shoulder, normally having a long barrel. Classified as single shot, semi-automatic, or fully automatic.

11. 16-11 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Parts of a Bolt Action Rifle

12. 16-12 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Types of Firearms Classification by design & purpose Handguns A firearm with a defined barrel length limit. Classified as single shot, revolvers, or semi- automatic pistols.

13. 16-13 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Types of Firearms Classification by design & purpose Handguns Single shot firearms are manually cocked before each shot. Revolvers have a rotating cylindrical cartridge holder, allowing the weapon to be fired semi- automatically. Semi-automatic pistols have a magazine in the grip that holds the ammunition. Empty cartridge cases are automatically ejected.

14. 16-14 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein 22 Ruger-Old Western Style Single Action

15. 16-15 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Parts of a Handgun

16. 16-16 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein 9 mm Glock

17. 16-17 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Types of Firearms Classification by design & purpose Shotguns Designed to be fired from the shoulder, having long barrels that are smooth. Shotgun shells contain either pellets or a slug packed into a cartridge along with the powder charge and primer

18. 16-18 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Types of Firearms

19. 16-19 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein The Firing Process The firing pin strikes the primer causing the shock-sensitive primer to ignite. The primer then transfers a spark or flame to the powder charge, located in the body of the case. The burning powder rapidly gives off heat and gases, and the pressure forces the projectile from the case and down the barrel of the weapon.

20. 16-20 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gun Barrel Markings 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.

21. 16-21 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gun Barrel Markings The manufacture of a barrel also requires impressing its inner surface with spiral grooves, a step known as rifling. The lands are surfaces of the original remaining bore. The grooves serve to guide a fired bullet through the barrel, imparting a rapid spin to insure accuracy.

22. 16-22 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein The Bore of Guns

23. 16-23 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein 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 lands. –So a.45 caliber bullet is 0.45 inches across. –Some newer bullets are measured in millimeters.

24. 16-24 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Design “Bullet” refers to the projectile(s) which actually exits the barrel of the gun when fired Bullets vary in shape and composition Hundreds of different types of bullets exist

25. 16-25 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Design Most types are variations on three main shapes & three basic compositions

26. 16-26 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Shape Round Nose Maximum penetration Cheapest shape to manufacture Easily loads into chambers

27. 16-27 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Shape Hollow Point Spreads or mushrooms on impact Causes additional damage to target Inhibits penetration

28. 16-28 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Shape Wad Cutter Used exclusively as a practice load Minimizes penetration Rips a hole in target paper which is visible by the shooter

29. 16-29 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Composition Lead ½ Jacketed Jacketed (full metal jacket)

30. 16-30 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Composition Lead Cheap Dense Soft Easy to mold

31. 16-31 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Composition ½ Jacketed A lead bullet coated with copper half way up the exposed portion of the bullet Used primarily for hollow points Copper improves exit velocity Lead promotes mushrooming

32. 16-32 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Composition Jacketed A lead bullet completely coated in copper Copper improves exit velocity and accuracy of the trajectory Used to hold the shape of the bullet in an effort to maximize penetration

33. 16-33 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein 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.

34. 16-34 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Shotguns The diameter of the shotgun barrel is expressed by the term gauge. The higher the gauge number, the smaller the barrel’s diameter.

35. 16-35 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Striations The inner surface of the barrel of a gun can leave striation markings on a bullet passing through it. Courtesy of C. Fanning

36. 16-36 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Striations The striations on the bullet can make identifiable and unique markings that trace it back to a particular firearm.

37. 16-37 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Examination Class Characteristics Once a manufacturer chooses a rifling process, the class characteristics of the weapon’s barrel will remain consistent –The number of lands and grooves –Width and direction of twist Any differences in these class characteristics immediately serve to eliminate the possibility that both bullets traveled through the same barrel.

38. 16-38 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Examination Individual Characteristics No two rifled barrels, even those manufactured in succession, will have identical striation markings.

39. 16-39 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Recovered Bullets Often, recovered bullets are so distorted by impact that it is very difficult to find individual characteristics, such as striations. If the distortion is extreme, class characteristics may be difficult to discover, as well.

40. 16-40 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Cartridge Examination Class Characteristics Usually brass or nickel-clad brass Head stamps Rimfire and centerfire cartridges

41. 16-41 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Cartridge Case Comparison The firing pin, breechblock, and ejector and extractor mechanism also offer a highly distinctive signature for individualization of cartridge cases. Courtesy of C. Fanning

42. 16-42 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Cartridge Case Comparison The shape of the firing pin will be impressed into the relatively soft metal of the primer on the cartridge case. The cartridge case, in its rearward thrust, is impressed with the surface markings of the breechblock.

43. 16-43 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Cartridge Case Comparison Other distinctive markings that may appear on the shell as a result of metal to metal contact are caused by the: –Ejector, which is the mechanism in a firearm that throws the cartridge or fired case from the firearm. –Extractor, which is the mechanism in a firearm by which a cartridge of a fired case is withdrawn from the firing chamber. –Magazine or clip, which is the mechanism that in a firearm holds the bullets.

44. 16-44 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Cartridge Examination Individual Characteristics Firing pin marks Breech marks Extractor marks

45. 16-45 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein 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.Calvin Goddardcomparison microscope

46. 16-46 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein 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.

47. 16-47 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Comparison Microscope Two scopes - One Field

48. 16-48 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Recovery Tank Each gun submitted is test fired and the recovered bullets and cartridge cases are retained for use in further analysis.

49. 16-49 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein

50. 16-50 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Bullet Comparison Examiner rarely finds a perfect match. –Grit & rust can alter markings –Bullets are distorted upon impact –Striations are continually altered Examiner may have a spent bullet, but no weapon and is asked to identify the caliber and possible make of the weapon.

51. 16-51 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging The use of firearms in crimes has increased significantly in the US. Because of the cost of the firearms, the likelihood that the same weapon is used in multiple crimes has also increased.

52. 16-52 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging The advent of computerized imaging technology has made possible the storage of bullet and cartridge surface characteristics in a manner similar to automated fingerprint files.

53. 16-53 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging In the early 1990s, both the FBI and the Bureau of Alcohol, Tobacco, Firearm & Explosives were developing computerized systems that were NOT compatible. FBI – DRUGFIRE ATF – Integrated Ballistics Information System (IBIS)

54. 16-54 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging FBI – DRUGFIRE Emphasized the examination of unique markings on cartridge casings expended by a weapon Analyzed using a microscope attached to a video camera

55. 16-55 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging ATF – IBIS Processed digital microscopic images of identifying features found on both the expended bullets and cartridge casings. –Bulletproof (bullet-analyzing module) –Brasscatcher (cartridge case analyzing module)

56. 16-56 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging The National Integrated Ballistics Information Network (NIBIN) ATF and FBI joined forces in 1999 –ATF has overall responsibility for system sites –FBI maintains communications network

57. 16-57 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging NIBIN serves only as a screening tool –May narrow the possibilities from hundreds of weapons to a few weapons The final comparison will be made by the forensic examiner through traditional microscopic methods.

58. 16-58 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Ballistic Fingerprinting Participating LE agencies are building databases of bullets and cartridge casings found at crime scenes and from test fires from weapons seized from criminals. Ballistic Fingerprinting is a proposed system to capture appropriate markings on bullets and casings from handguns and rifles BEFORE they are sold.

59. 16-59 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue When a firearm is discharged, unburned and partially burned particles of gunpowder in addition to smoke are propelled out of the barrel along with the bullet toward the target.

60. 16-60 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue If the muzzle of the weapon is close enough, these products will be deposited onto the target. An assessment of the distance from which a handgun or rifle was fired permits distance determination.

61. 16-61 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Distance Determination Important in determining self-defense and suicides Accuracy relies on having the suspect weapon in hand and knowledge of the type of ammunition used.

62. 16-62 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue The precise distance that a handgun or rifle was fired is determined by carefully comparing the powder-residue pattern located on the victim’s clothing or skin against test patterns made when the suspect weapon is fired at varying distances from a target.

63. 16-63 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue General Observations Less than 1” away or in contact –Heavy concentration of lead around entrance hole –Loose fibers show scorch marks –Star-shaped tear pattern around the hole

64. 16-64 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue General Observations 12-18” away –Halo of lead around entrance hole –Scattered specks of powder grains without the presence of soot

65. 16-65 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue General Observations 3 feet or more –Dark ring around the bullet hole (bullet wipe) formed as the bullet passes through the target, depositing bullet lubricant and propellant byproducts around the edges of the entrance hole. –No visible gunshot residue

66. 16-66 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Shotgun Impact Patterns Firing distances involving shotguns must also be related to test firing. Muzzle to target distances are established by measuring the spread of the discharged shot. Generally, the pattern made by a 12-gauge shotgun increases 1” for each yard of distance –10” pattern produced at 10 yards

67. 16-67 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Shotgun Impact Patterns Choke is the amount of constriction placed on the muzzle at the end of the barrel.  Full choke ~ 50 yds  Modified choke ~ 35 yds  Improved cylinder ~ 20 yds  Sawed-off ~ 10 yds

68. Shotgun injuries

69. 16-69 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue When garments or other evidence relevant to a shooting are received in the crime laboratory, the surfaces of all items are first examined microscopically for the presence of gunpowder residue.

70. 16-70 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Powder Residues on Garments Lack of color contrast between powder and garment or the presence of heavily encrusted deposits of blood may prevent visual detection of gunpowder. Infrared photography can sometimes show better contrast with the burned powder and the cloth of a victim.

71. 16-71 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder Residue Nitrites are one type of chemical product resulting from the incomplete combustion of nitrocelluose powder. The Greiss test is used to detect gunpowder residues that are not visible. Photographic paper is pressed onto target with hot iron and then treated chemically.

72. 16-72 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Primer Residue on Hands The firing of a weapon not only propels residues toward the target, but gunpowder and primer residues are also blown back toward the shooter. Residue traces are often deposited on the firing hand of the shooter.

73. 16-73 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Primer Residue on Hands With the exception of most.22 caliber ammunition, primers contain a blend of lead styphnate, barium nitrate and antimony sulfide. Examiners measure the amount of barium and antimony on the relevant portion of the suspect’s hands, such as the thumb web, the back of the hand, and the palm.

74. 16-74 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Testing for Primer Residue Swabbing Cotton moistened with 5% nitric acid is swabbed on both firing and nonfiring hands and analyzed for barium and antimony In the case of suicides, hands are swabbed before the body is moved, or protected with paper bags.

75. 16-75 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Testing for Primer Residue Swabbing Low rate of positive findings because hands must be swabbed within 2 hours of shooting Residues are readily removed with washing, rubbing or wiping of hands Cannot be used to detect with most.22 caliber rim-fire ammunition Some labs don’t except cotton swabs taken from living people after 6 or more hours.

76. 16-76 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Testing for Primer Residue Adhesive Tape Examiners apply tape to the hand’s surface in order to remove any residue particles and examined with a scanning electron microscope (SEM). If the SEM is linked to an x-ray analyzer, an elemental analysis is conducted –Combination of lead, barium and antimony confirms primer residue particles

77. 16-77 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Primer Residue on Hands SEM is much more specific than swabbing, but requires excessive operator time. Developing automated particle search and identification systems

78. 16-78 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Primer Residue on Hands Neutron activation analysis Very few crime labs use because of the need for a source of neutrons and expensive equipment Atomic absorption spectrophotometry Lower cost allows many labs to use this instrument for the detection of barium and antimony

79. 16-79 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Serial Numbers Many manufactured items – including firearms – are impressed with a serial number for identification In many cases, the serial numbers on weapons used in crimes have been removed or obliterated by grinding, rifling or punching.

80. 16-80 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Serial Numbers Restoration of serial numbers is possible through chemical etching (acid) because the metal crystals in the stamped zone are placed under a permanent strain that extends a short distance beneath the original numbers.

81. 16-81 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Serial Numbers Obliterated surface is thoroughly cleaned, and polished to a mirrorlike finish. A reagent is swabbed onto the surface and the strained area will dissolve faster than the undamaged area, revealing the etched pattern.

82. 16-82 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence Collection Firearms are collected by holding the weapon by the edge of the trigger guard or by the checkered portions of the grip. Do NOT stick a pencil down the barrel. It disturbs evidence.

83. 16-83 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence Collection When a revolver is recovered, the chambers, their positions, and corresponding cartridges must be recorded. Firearm evidence must be marked for identification (usually a tag on the trigger guard) and a chain of custody must be established.

84. 16-84 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence Collection Before the weapon is sent to the laboratory, all precautions must be taken to prevent accidental discharge of a loaded weapon. In most cases, it will be necessary to unload the weapon. If wet, do not try to dry it. You will wipe evidence off. Preserve the condition until it gets to the lab.

85. 16-85 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence Col lection Bullets recovered at the crime scene are scribed with the investigator’s initials, either on the base or the nose of the bullet. The obliteration of striation markings that may be present on the bullet must be scrupulously avoided.

86. 16-86 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence Col lection The investigator must protect the bullet by wrapping it in tissue paper before placing it in a pillbox or an envelope for shipment to the crime laboratory.

87. 16-87 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence Collection Fired casings must be identified by the investigator’s initials placed near the outside or inside mouth of the shell. Discharged shotgun shells are initialed on the paper or plastic tube remaining on the shell or on the metal nearest the mouth of the shell.