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CRIM B12

CRIM B12. Physical Evidence. Locard’s Exchange Principle states that a criminal always removes something from the crime scene or leaves behind incriminating evidence. According to Locard, whenever two surfaces come into contact, a transfer of evidence, however slight, will occur.

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CRIM B12

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  1. CRIM B12

  2. Physical Evidence Locard’s Exchange Principle states that a criminal always removes something from the crime scene or leaves behind incriminating evidence. According to Locard, whenever two surfaces come into contact, a transfer of evidence, however slight, will occur.

  3. Firearms and Toolmarks

  4. big schnoz

  5. Toolmarks Tools leave marks by compression, gliding, and cutting. The microscopic marks left by the tool are known as striations In theory, a tool can be matched to a toolmark by matching the striation pattern Over time, the tool surface may change due to usage or corrosion.

  6. Toolmarks

  7. Internal ballistics: the bullet’s actions within the gun Transitional Ballistics: flight of the bullet Terminal ballistics: the bullet’s affect upon the target

  8. Firearms In firearms, microscopic striations are left by components of the weapon. The semi-automatic handgun, the components are: • Barrel (revolver) • Firing Pin (revolver) • Chamber • Breech Face (revolver) • Extractor • Ejector

  9. Slide Barrel Receiver The semi-automatic handgun consists of three main groups, the barrel, frame and slide.

  10. sight lock slide sight hammer barrel receiver grip triggerguard trigger magazine release magazine well

  11. sight cylinder sight hammer barrel release grip frame trigger guard trigger

  12. Rifling and Twist

  13. Projectile Components

  14. Bullet Types

  15. Bullet Deformation

  16. Striations

  17. Striations

  18. Shotgun Shell

  19. Casing Markings

  20. Firing Pin Impression Split Image

  21. Breech Face Impression

  22. Extractor Markings

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