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

5. big schnoz

6. 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.

7. Toolmarks

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

9. 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

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

11. sight
lock
slide
sight
hammer
barrel
receiver
grip
trigger guard
trigger
magazine release
magazine well

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

13. Rifling and Twist

15. Projectile Components

16. Bullet Types

17. Bullet Deformation

18. Striations

19. Striations

20. Shotgun Shell

21. Casing Markings

22. Firing Pin Impression
Split Image

23. Breech Face Impression

24. Extractor Markings