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Fs Ch 8

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Fs Ch 8

  1. 1. Firearms, Tool Marks, and Other Impressions Chapter 8
  2. 2. Firearms <ul><li>Quite the collection of fireamrs </li></ul>
  3. 3. Handguns <ul><li>Single-shot </li></ul><ul><li>Revolvers </li></ul><ul><li>Semi-automatic </li></ul><ul><li>Automatic </li></ul>
  4. 4. Revolver <ul><li>The live rounds are placed into the cylinder </li></ul>
  5. 5. Revolver <ul><li>A loaded revolver </li></ul>
  6. 6. Revolver <ul><li>Some guns just command your attention </li></ul>
  7. 7. Revolver <ul><li>Loading a revolver </li></ul>
  8. 8. revolvers <ul><li>Many types </li></ul>
  9. 9. Revolvers <ul><li>This one is too pretty to shoot. </li></ul>
  10. 10. Semi-automatics <ul><li>Utilize a magazine and internal feeding system </li></ul>
  11. 11. Semi-automatics <ul><li>Various models </li></ul>
  12. 12. Semi-Automatics <ul><li>Internal workings of a semi-auto </li></ul>
  13. 13. Semi-automtaics <ul><li>Stove pipe: The ejected shell casing is jammed in the ejector port </li></ul>
  14. 14. Long Guns <ul><li>Long guns: Multiple types </li></ul><ul><li>single-shot/repeating/semi-automatic/automatic </li></ul><ul><li>Shotguns </li></ul><ul><li>Shot </li></ul><ul><li>Choke </li></ul><ul><li>Rifles </li></ul><ul><li>Lands and grooves </li></ul>
  15. 15. Rifles <ul><li>Bolt action, pump action and lever action </li></ul>
  16. 16. Shotguns <ul><li>Wide varieties </li></ul>
  17. 17. Shot gun <ul><li>Another pretty gun </li></ul>
  18. 18. Introduction <ul><li>Structural variations/irregularities </li></ul><ul><ul><li>A bullet to a gun </li></ul></ul><ul><ul><li>A scratch or abrasion mark to a single tool </li></ul></ul><ul><ul><li>A tire track to a particular automobile </li></ul></ul><ul><li>Individualization: firearm/tool mark examination. </li></ul>
  19. 19. Gun Barrel Markings <ul><li>Gun barrel: steel bar hollowed by drilling. </li></ul><ul><li>Drill marks: randomly irregular/unique </li></ul><ul><li>Bullet picks up marks of barrel/unique to each gun. </li></ul><ul><li>Particular to each gun. </li></ul>
  20. 20. Gun Barrel Markings <ul><li>Muskets/pistols: smooth barrels/poor accuracy & range </li></ul><ul><li>Rifling: Spin on bullet </li></ul><ul><li>Lands: Surfaces between grooves </li></ul><ul><li>Grooves: Spiral cuts in barrel </li></ul>
  21. 22. Lands and grooves <ul><li>Don’t try this at home! </li></ul>
  22. 24. Gun Barrel Markings <ul><li>Caliber: barrel diameter </li></ul><ul><li>Manufacturing rifling process: class characteristics remain consistent. </li></ul>
  23. 25. Striations <ul><li>Striations: </li></ul><ul><li>Manufacturing Process </li></ul><ul><li>Left on bullets </li></ul><ul><li>Individual characteristics of barrel. </li></ul><ul><li>Striations: No 2 alike. </li></ul>
  24. 26. Bullet <ul><li>Note the striations on the fired bullet. These are unique to the gun that fired it. </li></ul>
  25. 27. Ammunition <ul><li>CARTRIDGE/ROUND: </li></ul><ul><li>Casing </li></ul><ul><li>Bullet </li></ul><ul><li>Powder </li></ul><ul><li>Primer </li></ul>
  26. 28. Ammo <ul><li>Various types of ammunition </li></ul>
  27. 29. Rifle cartridge <ul><li>Internal view </li></ul>
  28. 30. Cartridge <ul><li>Internal view </li></ul>
  29. 31. Rifle cartridges <ul><li>Various calibers </li></ul>
  30. 32. Firearm Examination <ul><li>Lands/Grooves/Twist: Start of exam </li></ul><ul><li>Differences: Eliminate as suspect. </li></ul>
  31. 33. The Comparison Microscope <ul><li>Comparison microscope: #1 tool </li></ul><ul><li>Not only must the lands and grooves of the test and evidence bullet have identical widths, but the longitudinal striations on each must coincide. </li></ul>
  32. 34. Comparison Microscope <ul><li>Using a comparison microscope an examiner can view both bullets at once </li></ul>
  33. 35. Examination <ul><li>This is an example of two fired bullets. The striations are identical. </li></ul>
  34. 36. Exams <ul><li>Another example of matching striations </li></ul>
  35. 37. Shotguns <ul><li>Smooth barrel. </li></ul><ul><li>Shot: Small pellets. </li></ul><ul><li>Gauge: Diameter of barrel. </li></ul><ul><li>High gauge=small diameter </li></ul>
  36. 38. Shot gun shell
  37. 39. Firing a Weapon <ul><li>Trigger pull: </li></ul><ul><li>Hammer falls </li></ul><ul><li>Firing pin strikes primer </li></ul><ul><li>Gases ignite and expand </li></ul><ul><li>Forcing bullet of barrel/picks up striations </li></ul>
  38. 40. Firing a Weapon <ul><li>Revolver: </li></ul><ul><li>Cylinder advances </li></ul><ul><li>Shell casings remain in weapon </li></ul><ul><li>5-8 rounds </li></ul>
  39. 41. Firing a Weapon <ul><li>Semi-auto: </li></ul><ul><li>Ejector: Casing out </li></ul><ul><li>Extractor: Next round </li></ul><ul><li>Breech lock: Back stop </li></ul><ul><li>All metal parts </li></ul>
  40. 42. Firing a weapon <ul><li>The hammer falls, hits the firing pin and the powder ignites sending the bullet down and out the barrel. There are a lot of gases and powders that are projected with bullet. </li></ul>
  41. 43. Cartridge/Shell Case Comparison <ul><li>Firing pin: Primer </li></ul><ul><li>Shell casing: </li></ul><ul><li>Ejector </li></ul><ul><li>Extractor </li></ul><ul><li>Breech lock </li></ul><ul><li>Magazine </li></ul>
  42. 44. Yikes <ul><li>Crime scene investigators nightmare. Each one of these casings needs to be marked, photographed, collected and packaged separately. </li></ul>
  43. 45. Head stamp <ul><li>The firing pin leaves a unique mark on the primer. </li></ul>
  44. 46. Head stamp <ul><li>Microscopic comparison of firing pin marks </li></ul>
  45. 47. Computerized Imaging <ul><li>National Integrated Ballistics Information Network, (NIBIN): </li></ul><ul><li>Bullets </li></ul><ul><li>Shell casings </li></ul><ul><li>Retrieved firearms </li></ul><ul><li>Firearms examiners v. Ballistics!!!!! </li></ul>
  46. 48. Gunpowder Residue <ul><li>Firearm discharged: Powder particles propelled. </li></ul><ul><li>Muzzle close: Powder on target. </li></ul><ul><li>Powder patterns: Estimate distance. </li></ul>
  47. 49. <ul><li>Powder and residue being projected. </li></ul>
  48. 50. <ul><li>Really being projected. </li></ul>
  49. 51. Gunpowder Residue <ul><li>Stellate wound: </li></ul><ul><li>Close contact (<1 inch) </li></ul><ul><li>Star shaped </li></ul><ul><li>Rim of lead </li></ul><ul><li>Halo: </li></ul><ul><li>12-18 inches </li></ul><ul><li>Stippling/Tattooing: </li></ul><ul><li>2-3 feet </li></ul><ul><li>Powder deposit </li></ul><ul><li>BAD PICTURES COMING UP!!!!!!!!!!!! </li></ul>
  50. 52. Close contact-Stellate wound
  51. 53. Close contact-Stellate wound
  52. 54. Impression of gun against skin
  53. 55. Impression of gun against skin
  54. 56. Impression of gun against skin
  55. 57. Stippling
  56. 59. Example of stippling
  57. 60. Stippling
  58. 61. Stippling
  59. 63. Gunshot wound no stippling
  60. 64. Gunshot wound entrance
  61. 65. Gunshot wound exit
  62. 66. Stellate wound-close contact
  63. 70. Stellate wound to skull
  64. 71. GSR on Hands <ul><li>Fired weapon: </li></ul><ul><li>GSR forward </li></ul><ul><li>GSR Back towards shooter </li></ul><ul><li>Extremely fragile </li></ul><ul><li>Valuable information </li></ul>
  65. 72. GSR <ul><li>Bang! That’s a lot of powder </li></ul>
  66. 73. GSR Test <ul><li>This is where you would expect to find GSR and where you swab for it </li></ul>
  67. 74. GSR <ul><li>Under a microscope </li></ul>
  68. 75. Serial Numbers <ul><li>Criminals obscure: </li></ul><ul><li>Permanently stamped under surface </li></ul><ul><li>Chemical etching </li></ul>
  69. 76. Serial restoration kit <ul><li>Combines acids and electricity to restore serial numbers </li></ul>
  70. 77. Firearm Evidence Collection <ul><li>How do you collect firearms? </li></ul><ul><li>Checkered grips </li></ul><ul><li>Prevent AD </li></ul><ul><li>Unload </li></ul><ul><li>Record cylinder location </li></ul><ul><li>Check for shells/live rounds </li></ul><ul><li>Mark/chain of custody </li></ul>
  71. 78. Firearm Evidence Collection <ul><li>Bullets: </li></ul><ul><li>Initials </li></ul><ul><li>Striation awareness </li></ul><ul><li>Cotton/pill bottle </li></ul><ul><li>Shell casings: </li></ul><ul><li>Initials </li></ul><ul><li>Shotgun shells: </li></ul><ul><li>Initials </li></ul>
  72. 79. Tool Marks <ul><li>Impression, cut, gouge, or abrasion </li></ul><ul><li>Examination: </li></ul><ul><li>Class characteristics </li></ul><ul><li>Size/shape </li></ul><ul><li>Individual characteristics </li></ul><ul><li>Minute imperfections </li></ul><ul><li>Wear/age </li></ul>
  73. 80. Tool Marks <ul><li>Comparison microscope: #1 instrument used. </li></ul><ul><li>Collecting tool marks: </li></ul><ul><li>Entire/part of object </li></ul><ul><li>Never fit tool into impression!!!! </li></ul>
  74. 81. Tool marks <ul><li>Microscopic view </li></ul>
  75. 83. Other Impressions <ul><li>Shoe/Tire: Important evidence. </li></ul><ul><li>Collecting: </li></ul><ul><li>Photographs (scale) </li></ul><ul><li>Recoverable item to lab </li></ul><ul><li>Alternative: Cast/lift </li></ul>
  76. 84. Impressions <ul><li>Footwear </li></ul>
  77. 85. Impressions <ul><li>Impressions compared to suspect’s shoe </li></ul>
  78. 86. Impressions <ul><li>Comparison in progress </li></ul>
  79. 87. Impressions <ul><li>Casting footwear impressions in dirt </li></ul>
  80. 88. Impression <ul><li>Wax spray is used to preserve footwear impressions in snow </li></ul>
  81. 89. Impressions <ul><li>Tire impressions </li></ul>
  82. 90. Points of Comparison <ul><li>Number of points? </li></ul><ul><li>New Computer technology </li></ul><ul><li>Bite Marks: </li></ul><ul><li>Food </li></ul><ul><li>Skin </li></ul><ul><li>Individual characteristics </li></ul><ul><li>PEOPLE SLIDES COMIN UP!!! 4 TH ONE IS ACTUAL DEAD PERSON </li></ul>
  83. 91. Bite marks <ul><li>Child abuse case </li></ul>
  84. 92. Bite marks <ul><li>Dental stone is used to make a cast impression of bite marks </li></ul>
  85. 93. Bite mark <ul><li>Tiger Shark bite mark-no suspect in custody </li></ul>
  86. 94. You decide <ul><li>Victim of attack. What did it? </li></ul>
  87. 95. You decide <ul><li>Examine the open wounds to the neck. Still don’t know? You will never guess! </li></ul>
  88. 97. Solution <ul><li>Here is the suspect. The victim was a tiger trainer who was in the enclosure when the tiger put his paws on the victim’s shoulders, opened his mouth and took the victim’s entire head into mouth. The tiger then just bit down and severed both the carotid arteries and the jugular veins. </li></ul><ul><li>The tiger was less than impressed to have his picture taken. </li></ul>

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