Hair

1. Hair CHS Forensics Mr. McNiff

2. Hair Glossary Introduction Basic Structure of Hair Hair Identification: Animal Versus Human Hairs Human Hair Classifications Methods of Hair Recovery Human Hairs Identification Comparison Characteristics Conclusions

4. Glossary • Achromat: An objective lens system constructed of glass with limited quality of correction for color and spherical aberration.

5. Glossary • Anagen: Actively growing root stage.

6. Glossary • Catagen: A transitional root stage between the actively growing anagen stage and the resting telogen stage.

7. Glossary • Comparison microscope: Two microscopes joined by an optical bridge with a split screen to see both fields of views at the same time. • Cortex: Middle portion of hair extending from the cuticle to the medulla and containing the pigment granules, cortical fusi, and ovoid bodies. • Cortical fusi: Air spaces located in the cortex of hairs.

8. Glossary • Cuticle: Translucent outer layer of the hair shaft consisting of overlapping scales. • Fluorite system: An objective system constructed of fluorspar that provides improved color and spherical correction over achromatic lens systems. • Fur hairs: Fine hairs that make up the undercoat of mammals and provide warmth.

9. Glossary • Guard hairs: Coarse hairs that provide protection and are usually longer than fur hairs. • Keratin: A fibrous protein forming the chemical basis for hair, nails, and feathers. • Medulla: The central portion of hair, the core area. • Melanin: A pigment that gives hair its color.

10. Glossary • Miscible: Able to be mixed together. • Oil immersion: A system that uses oils of a known refractive index to test the refractive index of other materials and provide greater resolution than air-mounted specimens.

11. Glossary • Ovoid bodies: Dark bodies of unknown origin that are a useful discriminatory characteristic in their pattern of appearance. • Papilla: Connective tissue from which hair is generated from the follicle.

12. Glossary • Pigment granules: Melanin granules whose size, shape, density, and distribution vary. • Refractive index: The ratio of the velocity of light in air to the velocity of light in a medium. • Resolving power: The ability of the microscope to make visible the individual parts of an image

16. Glossary • Scales: Outermost portion of the cuticle, flattened and imbricate in humans, pointing toward the distal end of the hair shaft. • Tactile hairs (Vibrissae): Whiskers only found on animals.

17. Glossary • Telogen: Resting stage when the root takes on club shape and is ready to be naturally shed. • Vellus: Fine body hair.

18. Hair Glossary Introduction Basic Structure of Hair Hair IdentificationAnimal Versus Human Hairs Human Hair Classifications Methods of Hair Recovery Human Hairs Identification Comparison Characteristics Conclusions

19. Hair Evidence • Each species of animal possesses hair with characteristic that distinguish one animal from another. • length • Color • Shape • Root appearance • Internal microscopic features

20. Introduction One of the most common types of physical evidence in a criminal investigation is hair evidence. The identification and comparison of human and animal hairs can be helpful in demonstrating physical contact with a suspect, victim, and crime scene.

21. Introduction Hairs can provide investigators with valuable information for potential leads. The first step necessary in the analytical process is the identification and comparison of human and animal hairs.

22. Introduction Microscopy of Hairs: A Practical Guide and Manual by John W. Hicks is intended to introduce hair evidence to the forensic examiner and to provide a foundation for its proper identification and comparison.

23. Hair Glossary Introduction Basic Structure of Hair Hair IdentificationAnimal Versus Human Hairs Human Hair Classifications Methods of Hair Recovery Human Hairs Identification Comparison Characteristics Conclusions

24. Basic Structure of Hair A hair can be defined as a slender, thread-like outgrowth from a follicle in the skin of mammals. Composed mainly of keratin, it has three morphological regions—the cuticle, medulla, and cortex.

25. 1. Hair Diagram

26. Basic Structure of Hair A hair grows from the papilla and with the exception of that point of generation is made up of dead, cornified cells. It consists of a shaft that projects above the skin, and a root that is imbedded in the skin

27. Cuticle

28. Hair Glossary Introduction Basic Structure of Hair Hair IdentificationAnimal Versus Human Hairs Human Hair Classifications Methods of Hair Recovery Human Hairs Identification Comparison Characteristics Conclusions

29. Hair IdentificationAnimal Versus Human Hairs • Human hairs are distinguishable from hairs of other mammals. Animal hairs are classified into the following three basic types. • Guard hairs that form the outer coat of an animal and provide protection • Fur or wool hairs that form the inner coat of an animal and provide insulation

30. Hair IdentificationAnimal Versus Human Hairs • Tactile hairs (whiskers) that are found on the head of animals provide sensory functions

31. Hair IdentificationAnimal Versus Human Hairs The medulla, when present in human hairs, is amorphous in appearance, and the width is generally less than one-third the overall diameter of the hair shaft. The medulla in animal hairs is normally continuous and structured and generally occupies an area of greater than one-third the overall diameter of the hair shaft.

32. Hair IdentificationAnimal Versus Human Hairs The root of human hairs is commonly club-shaped, whereas the roots of animal hairs are highly variable.

33. Human Hairs bsapp.com

34. Horse Hair bsapp.com

35. Dog Hair bsapp.com

36. Cat Hair bsapp.com

37. Mouse Hair bsapp.com

38. Rabbit Hair bsapp.com

39. Deer Hair bsapp.com

40. Cow Hair bsapp.com

41. Pig Hair bsapp.com

42. Hair Glossary Introduction Basic Structure of Hair Hair IdentificationAnimal Versus Human Hairs Human Hair Classifications Methods of Hair Recovery Human Hairs Identification Comparison Characteristics Conclusions

43. Human Hair Classifications Hair evidence examined under a microscope provides investigators with valuable information. Hairs found on a knife or club may support a murder and/or assault weapon claim.

44. Human Hair Classifications A questioned hair specimen can be compared microscopically with hairs from a known individual, when the characteristics are compared side-by-side.

45. Hair sample at left from victim's vehicle and suspect's hair at right

46. Human Hair Classifications • Human hairs can be classified by racial origin: • Caucasian (European origin), • Negroid (African origin), • Mongoloid (Asian origin). • In some instances, the racial characteristics exhibited are not clearly defined, indicating the hair may be of mixed-racial origin.

47. Human Hair Classifications The region of the body where a hair originated can be determined with considerable accuracy by its gross appearance and microscopic characteristics.

48. Human Hair Classifications The length and color can be determined. It can also be determined whether the hair was forcibly removed, damaged by burning or crushing, or artificially treated by dyeing or bleaching.

49. Fallen Out Hairs bsapp.com

50. Natural Tip bsapp.com