Amc week 13 impression new ballistics and final review


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Amc week 13 impression new ballistics and final review

  1. 1. Impression Evidence
  2. 2. Impression Evidence <ul><li>Just like fingerprints and palmprints </li></ul><ul><ul><li>Looking for similarities and differences </li></ul></ul><ul><li>Class and Individual Characteristics </li></ul><ul><ul><li>Class is shared by like items </li></ul></ul><ul><ul><ul><li>It’s a size 9 Reebok Perimeter </li></ul></ul></ul><ul><ul><li>Individual is unique to individual evidence </li></ul></ul><ul><ul><ul><li>It’s this size 9 Reebok Perimeter </li></ul></ul></ul>
  3. 4. Shoe Print Case <ul><li>Respond to Woonsocket Plaza for Larceny of Copper </li></ul><ul><li>Find Shoeprints on the Black Tar Rubberized Roof near the Air Conditioning Units </li></ul><ul><li>Follow prints to edge of building finding point of entry </li></ul><ul><li>Send shoeprints to FBI (maintain a database of shoe impressions) </li></ul><ul><li>FBI identifies shoe as a Reebok Perimeter </li></ul>
  4. 9. Firearms and Ballistics
  5. 10. How a gun works
  6. 11. Four Components of Ammunition <ul><li>Primer </li></ul><ul><ul><li>Rimmed or Centerfire </li></ul></ul><ul><li>Cartridge Case or Shotshell </li></ul><ul><li>Propellant </li></ul><ul><li>Projectile(s) </li></ul>
  7. 12. Ammunition
  8. 13. Ammunition
  9. 14. PREMIUM LOAD with SHOTCUP Pellets do not contact bore
  10. 17. Some problems
  11. 18. Stable vs. Instable Projectile Flight
  12. 19. Rifling
  13. 23. <ul><li>When a firearm is manufactured, the individual parts are made with tools that are in a constant state of change </li></ul><ul><li>As a result, no two guns will leave the same marks on the ammunition components </li></ul><ul><li>The marks found on bullets are sometimes referred to as striations </li></ul>
  14. 25. The match on the bullet
  15. 26. Gunshot Residue
  16. 27. Source of Gunshot Residue <ul><li>Firing a weapon may cause microscopic particles of primer residue and gunpowder to be deposited on the hands of the shooter </li></ul><ul><li>The higher the caliber, the more GSR depositied on hands </li></ul><ul><li>.22 caliber rim-fire cartridges will sometimes not show traditional GSR particles </li></ul>
  17. 28. Primers <ul><li>Lead Styphnate </li></ul><ul><ul><li>Primary explosive </li></ul></ul><ul><li>Barium Nitrate </li></ul><ul><ul><li>Oxygen Source </li></ul></ul><ul><li>Antimony Sulfide </li></ul><ul><ul><li>Fuel </li></ul></ul>
  18. 29. Formation of the Particle <ul><li>Upon detonation, the compounds of the primer vaporize, mix and then condense back into particles </li></ul><ul><li>The result: what was once three separate particles have become one particle made up of lead, barium and antimony </li></ul>
  19. 30. Inside a GSR kit <ul><li>Each GSR kit contains </li></ul><ul><ul><li>Instructions </li></ul></ul><ul><ul><li>A pair of rubber gloves </li></ul></ul><ul><ul><li>Labels </li></ul></ul><ul><ul><li>Two sample vials </li></ul></ul><ul><li>Each vial contains adhesive coated aluminum stub mounted on the base of a rubber stopper </li></ul><ul><li>Stub pressed and lifted on the surface being sampled </li></ul><ul><ul><li>Hand </li></ul></ul><ul><ul><li>Face </li></ul></ul><ul><ul><li>Clothing </li></ul></ul>
  20. 31. The Examination <ul><li>Look for particles with the proper morphology and size </li></ul><ul><li>Look for particles which contain all three components of the primer </li></ul><ul><ul><li>Lead (Pb) </li></ul></ul><ul><ul><li>Barium (Ba) </li></ul></ul><ul><ul><li>Antimony (Sb) </li></ul></ul>
  21. 32. Positive: What does it mean? <ul><li>The individual fired a weapon </li></ul><ul><li>The individual handled a weapon right after it was fired </li></ul><ul><li>The individual was very near when the gun was fired </li></ul><ul><li>The individual touched a surface that had GSR on it. </li></ul><ul><li>Etc, etc, etc. </li></ul>
  22. 33. Negative: What does it mean? <ul><li>The individual did not fire a weapon </li></ul><ul><li>The individual washed their hands </li></ul><ul><li>The sample was collected after the recommended 4-6 hour time window </li></ul><ul><li>The individual was wearing gloves when they fired the weapon </li></ul><ul><li>Etc, etc, etc. </li></ul>
  23. 34. Bullet Trajectory
  24. 35. Projectile Penetration <ul><li>Three Possibilities </li></ul><ul><ul><li>Projectile is stopped by impact without penetration </li></ul></ul><ul><ul><li>Projectile will penetrate the object without exiting </li></ul></ul><ul><ul><li>Projectile will pass through object (Perforate) </li></ul></ul>
  25. 36. Definitions <ul><li>Penetration </li></ul><ul><li>Penetration is when a projectile enters but does not exit. Not to be confused with Perforation </li></ul><ul><li>Perforation </li></ul><ul><li>Perforation is when a projectile passes through and through. Not to be confused with Penetration </li></ul>
  26. 40. Shotgun Pellet Patterns In General…. For every 1” across = 1 Yard from Muzzle 7” Muzzle to Target = 7 Yards
  27. 41. Pellet Pattern Diameter vs. Range Orthogonal Impacts d d d
  28. 42. Non-Orthogonal Pellet Patterns sin -1 (d/D) = incidence angle
  29. 43. Orthogonal Strikes No. 4 Buck 12-ga. d = 7 in.
  30. 44. 45 0 Incident Angle with No. 4 Buck, 12 ga. d = 7 in. d/D = 0.67 Sin -1 = 42 0 Same Range as previous shot
  31. 52. Everything from Midterm Plus Ballistics Ammo components Chemicals Rifling Striations GSR What it means Trajectory Penetration Perforation Shotgun 1” for 1 yard Casings Glass – 2 shots which one first Difference between class and individual characteristics Blood Spatter Definitions Formula LVIS MVIS HVIS Tests Eyewitness Polygraph 3 measurements Physiological changes Heart Respiration Perspiration Reaction Eyes Cotton mouth Butterflies