1. Microscopy

2. Important microscopy terms “Real” and “virtual” image “Real” and “virtual” image “Transmitted” or “reflected” light “Transmitted” or “reflected” light Parfocal Parfocal

3. The Principle of the Compound Microscope. The passage of light through two lenses forms the virtual image of the object seen by the eye.

4. Compound Microscope.

5. Comparison compound microscope Hair and Fiber analysis Hair and Fiber analysis

6. Gun barrels leave “lands” and “grooves” on the bullets surface.

7. Ballistics Examinations

8. Stereoscopic Microscope.

9. Comparison stereoscopic microscope

10. Dissecting microscope Sometimes used in combination with compound or stereoscopic microscopes e.g. paint analysis. Sometimes used in combination with compound or stereoscopic microscopes e.g. paint analysis.

11. Scanning Electron Microscope (S.E.M.). - designed for direct studying of the surfaces of solid objects. - allows a greater depth of focus and magnification than the optical microscope. - produce an image that is a good representation of the three-dimensional sample.

13. Hair, Fibers and Paint Analysis.

14. Identification and Comparison of Hair 1. Human or animal? 1. Human or animal? Muskrat hair Deer hair Human hair 2. Comparison of crime scene versus suspect hair. 2. Comparison of crime scene versus suspect hair. Remember hair is class evidence!

15. Collection of Hair Evidence Must have a number of control samples Must have a number of control samples Must have hair samples from different parts of the body. Must have hair samples from different parts of the body.

16. What is hair? Appendage of skin that grows out of an organ called a hair follicle. Appendage of skin that grows out of an organ called a hair follicle. Root (or bulb) is embedded in the follicle Root (or bulb) is embedded in the follicle  Extends into shaft  terminates at the tip.

18. Shaft is composed of three layers: - Cuticle - Cortex - medulla

19. Cuticle Overlapping scales Overlapping scales - Keratinized cells What species? 1. Coronal 2. Imbricate 3. Spinous

21. Cortex Contained within the protective layer of the cuticle Contained within the protective layer of the cuticle - spindle shaped cells and pigment granules. - spindle shaped cells and pigment granules.

22. Medulla Classified as: Classified as: - absent - continuous__________ - interrupted--------------- - fragmented- -- - - ----

23. Medulla cont… Medullary index: Medullary index: < 1/3 ……human > 1/2 ………animal Medulla shape Medulla shapecylindrical…..humanpatterned……animal

24. Shape of the root of the hair Naturally shed hairs, such as a head hair dislodged through combing display undamaged, club-shaped roots. A hair forcibly removed from the scalp will exhibit stretching and damage to the root area. Forcibly removed hairs may have tissue attached.

25. Hair Root Three phases of hair growth: Three phases of hair growth: 1. Anagen 2. Catagen 3. Telogen After 2-6 months the hair will be pushed out of the follicle and shed..

26. Fibers as Evidence Fibers are an important part of trace evidence used to track suspects. Fibers are an important part of trace evidence used to track suspects.

27. Fiber Analysis 1. Natural fibers 1. Natural fibers e.g. wool (sheep), mohair, cashmere (goats), fur (mink, beaver etc) 2. Manmade fibers 2. Manmade fibers - regenerated fibers e.g. rayon, acetate, triacetate - synthetic fibers e.g. nylon, polyester, acrylic

28. Natural Fibers Cotton FibersCotton Fibers  Wool fibers Flax fibers (viewed with polarized light).Flax fibers (viewed with polarized light).

29. Manmade fibers Cross-sections of man-made fibers (viewed with S.E.M.)

30. What are polymers? Basic chemical substance of all synthetic fibers and materials.

31. Polymers, also known as macromolecules, are made up of repeating units called monomers. Polypropylene

32. Identification and Comparison of Manmade fibers. 1. Color and diameter 2. “Pitting”? 3. Dye comparison 4. Chemical composition 5. Physical properties.

33. Collection of Fiber Evidence Identify and preserve potential “carriers” of fiber evidence. Identify and preserve potential “carriers” of fiber evidence. Package “carriers” separately. Package “carriers” separately. Fold in correct manner. Fold in correct manner.

34. Paint as Evidence

35. Paint. Paint dries to a hard polymeric film consisting of: Paint dries to a hard polymeric film consisting of: 1. Pigments 2. Additives. 3. Binder

36. Automotive Paints. 1. Electrocoat primer 2. Primer surfacer 3. Basecoat 4. Clearcoat.

37. Chemical Composition. 1. Pyrolysis Gas Chromatography - can distinguish most paint formulations 2. Infrared Spectrophotometry - binders selectively absorb the IR radiation. 3. Elemental Analysis - inorganic pigments are analyzed.

38. Collection and Preservation of Paint Evidence. Control samples Control samples All samples should be 0.5cm square All samples should be 0.5cm square Package separately Package separately Chain of Custody Chain of Custody