0. Chp. 10 Hair Analysis

1. PLEASE DO NOW
How many hairs does the average person have on his/her head?
All
Brown hair
Red hair
Blond hair
What information can a forensic scientist determine from a human hair?

2. Hair as Evidence Continually falls from the body
About 100 hairs fall out each day
Not readily lost or displaced
Goes unnoticed by criminal
Not easily destroyed
Useful associative evidence since it originates directly from the individual

3. Hair Structure
Hair = epidermal appendage that grows out of the skin from an organ known as the follicle
Root = portion of hair that lies in follicle
Bulb = enlarged base of root
Dermal papilla = connective tissue surrounded by bulb
Shaft = portion of hair above skin’s surface
Composed primarily of keratin
Feature unique to mammals

5. Hair Growth Average period of hair growth 1,000 days
Grows 1 cm per month
3 distinct growth phases
Anagen (80-90% of hairs)
Follicle actively producing hair
Catagen (2% of hairs)
Transitional period
Telogen (10-18% of hairs)
Follicle dormant/resting

6. Hair Growth Anagen Phase
Cells in dermal papilla undergo mitosis and grow up to form hair shaft
Bulb is described as flame shaped

7. Hair Growth Catagen Phase
Cells in the shaft continue to differentiate but no more pigmentation or color produced in hair towards root
Bulb of the root shrinks and becomes surrounded by the club – a capsule of cells

8. Hair Growth Telogen Phase Hair anchored in follicle only by club
Germ cells below club getting ready to form next hair
Dermal papilla looks like a ball below germ cells waiting to be surrounded by next bulb

9. Hair Structure The shaft of the hair has 3 layers
Cuticle = thin translucent scale layer surrounding shaft
Cortex = main body of hair shaft
Medulla = central canal-like structure

10. Cuticle
Made up of overlapping, nonnucleated, pigment-free, keratinized cells that have formed scales
As many as 6 layers of scales per hair
Scales always point away from the root
Outer and inner cuticle margins can be:
Cracked
Ragged
Serrated
Flattened

11. Cuticle

12. Cuticle Viewing cuticle scales Mount hair between glass slides
Prepare a clear cast of the cuticular surface
Scanning electron microscope

13. Cortex
Composed of elongated keratinized filaments aligned together parallel to the length of the hair
Contained within cells of cortex
Cortical fusi = delicate air spaces
Vary in amount, size, shape and distribution
Appear dark with transmitted light and bright with direct light
Hair pigment = solid structure that gives hair color
Vary in size, shape, distribution and density
Appear dark and granular
Smaller than cortical fusi
Ovoid bodies
Solid structures that are oval in shape
Larger than pigment granules

14. Cortex

15. Cortex

16. Medulla Cellular column running through the center of the cortex
Function is to increase protective properties of hair by adding internal space
Medulla structure on humans is amorphous
Pattern can be absent, fragmental, interrupted, or continuous
Appearance will vary from person to person and within hairs of the same individual

17. Medulla

18. Hair as Evidence Class evidence
Have to compare evidence against reference samples
To collect samples:
Bright light aids in the visualization of questioned hairs at a crime scene
Stored in paper packets or between sealed glass slides
Wide transparent tape obtains difficult to see hairs from clothing and carpets
Note location from where collected
To collect reference samples:
Collected from both victim and suspect
About 50 samples collected for comparison
Should be combed and pulled to represent all growth stages
Should be taken from each region of the area
Must represent any chemically treated areas of the hair

19. Identification of Human Hair
First step in the forensic investigation of human hair is to identify the hair in question in the following categories:
Species Origin
Racial Origin
Somatic Origin
A direct comparison with a reference hair can only be made after the hair is classified in this way

20. Species Origin 3 Types of Animal Hairs Vibrissa
Tactile and sensitive whiskers
Largest and longest hairs on body usually
Bristle/Guard
Coarse hairs that make up the protective outer coat
Distinctive in appearance and morphology between different animal families
Wool/Fur
Fine short hairs that cover the body and make up the inner coat
Provides insulation from wet and cold

21. Species Origin 4 Types of Human Hairs Primordial
Coarse and whisker like
Appear during 3rd month of gestation
Grow on upper lips, eyebrows, palms and soles of fetus
Lanugo
Fine, soft, unmedullated and unpigmented
Replace primordial hairs but shed after 6 months of gestation
Vellus
Fine, soft, unmedullated and short (2 cm)
Spread uniformly over body surface except for palms, soles, lips, and nipples
Terminal
Replace vellus hairs at specific sites and stages of life
Scalp and eyebrows, pubic areas, face, chest, back, arms and legs

22. Species Origin Cuticle Human
Imbricate scales = scales are small, flattened and with little serration
Animal
Exhibit a wide range of cuticular patterns

23. Species Origin - Cuticle
Human Hair – Imbricate Scales
Mink Hair – Spinous Scales
Bat Hair – Coronal Scales

24. Species Origin Cortex Human Untreated human hair is uniform in color
Pigmentation granules are evenly distributed or slightly more dense toward cuticle
Animal
Hairs exhibit rapid color changes along the shaft called banding
Pigmentation granules are more dense toward the medulla

25. Species Origin - Cortex
Pigment Distribution in Human Hair
Pigment Distribution in Animal Hair

26. Species Origin Medulla Human Rarely 1/3 width of hair shaft
Structure is amorphous
Pattern can be absent, fragmented, interrupted, or continuous
Animal
More than 1/2 width of hair shaft
Distinct medulla structure between species

27. Species Origin - Medulla
Uniserial and Multiserial Ladder Medulla in Rabbit Hairs
Vacuolated Medulla in Dog Hair
Lattice Medulla in Deer Hair

28. Racial Origin Caucasian 70-100 μm Oval Even Medium Uncommon Asian
Diameter
Cross Section
Pigmentation
Cuticle
Undulation
Caucasian μm
Oval
Even
Medium
Uncommon
Asian μm
Round
Dense
Thick
Never
African American
60-90 μm
Flat
Dense and Clumped -
Prevalent

29. Caucasian Hair

30. Mongoloid (Asian) Hair

31. Negroid (African American) Hair

32. Somatic Origin
Scalp: Head hair, mm long, um diameter; 0.4 mm/day
growth; small root; tapered tip; little diameter variation; various
medullation; often with cut tips may be artificially treated
Pubic: Pudendal; mm long; coarse diameter and prominent
diameter variation and buckling; broad medulla; follicular tags
common; asymmetrical cross section twisted and may be straight,
curved, or spirally tufted
Vulvar: Secondary pubic hair; finer and shorter; may be abraded
Chest: Pectoral; moderate to considerable diameter variation; long fine
archlike tip; usually longer than pubic hair
Beard: Facial hair; very coarse; mm long; large root, irregular
structure; often triangular cross section; complex medullation;
blunted or razor cut tip; grows 0.4 mm/day
Axillary: Arm pit; mm long; grows 0.3 mm/day; coarse; blunt tip,
abraded or frayed; usually straighter than pubic hair; many cortical
fusi; sometimes yellowed and bleached
Eyebrow: 1 cm long; 0.16 mm/day growth; curved; relatively coarse for
length; smooth curve with punctuate tip and large medulla
Eyelash: Ciliary; less than 1 cm long; short curved pointed hair
Limb: Leg and arm hair; 3-6 mm long; fine tip; irregularly medullated;
often indistinctly and slightly pigmented
Ear: Tragi; pinnae; downy
Buttocks: Anal hair; short blunted and abraded hair
Nose: Similar to facial hair (beard)

33. Pubic Hair
Limb Hair
Beard Hair

34. Association of Human Hair
Characteristics used for hair comparison
Structure
Color
Cuticular Traits
Length
Acquired Characteristics

35. Structure of Hair

36. Color of Hair

37. Cuticular Traits

38. Acquired Characteristics

39. Scissor Cut
Razor Cut
Split End
Broken/Clippers

40. Microscopy 3 types of microscope used: Mounting choices
Stereoscopic Microscope - gross observations of the hairs
Study trace evidence on the hair’s surface, spatial configuration, roots, and tips
Compound or Polarizing Microscope - allows for higher magnification and resolution
Delineates hair’s finer structural characteristics (pigment, scale, structure, cortical fusi, medulla)
Transmitted Light Comparison Microscope - compare known and unknown hairs side-by-side
Mounting choices
Dry mount
Temporary liquid mounting media
Permanent mounting media

41. Conclusions from Comparisons
One of 3 conclusions can be reached:
The hairs matched in microscopic characteristics indicating an association
The hairs were not alike and therefore did not originate from the same individual
No conclusion can be drawn from the evidence
Factors affecting degree of certainty associated with conclusion:
Number of unknown hairs found to be similar to reference hairs
Number of microscopic features observed
The presence of unusual characteristics
Condition of specimens
Completeness of reference sample collection

42. Was Hair Forcefully Removed?
Look for follicular tag
Tissue from the follicle attached to the root of the hair
If a hair pulled from the body was securely attached to the follicle (anagen stage) a follicular tag will be present
If there:
Yes hair was pulled out
If absent:
Could have fallen out naturally
Could have been pulled out but cannot tell because
If the hair was in the telogen phase, no tissue would be attached
Some individuals lack follicular tissue on plucked anagen hairs

43. A hair forcibly removed from the scalp will exhibit stretching and damage to the root area
(PULLED)
Forcibly removed hairs may have tissue attached called the follicular tag
Naturally shed hairs dislodged through combing display undamaged, club-shaped roots

44. Is Hair from a Dead Body? Look for postmortem banding If present:
A dark band around the hair near the root where the skin surface meets the hair shaft
Found on hairs pulled from decomposing skin
If present:
May indicate that the body was moved after death

45. Individualization of Human Hair
DNA allows for the individualization of hair
Nuclear DNA
Found in the follicular tag
Will identify hair with one individual
Mitochondrial DNA
Found throughout cells of hair
Will identify hair to individuals of the same maternal line

46. Quick Review
Human hair is one of the most frequently found pieces of evidence at the scene of a violent crime. It can provide a link between the criminal and the crime.
From hair one can determine:
If the source is human or animal
Race (sometimes)
Origin of the location on the source’s body
Whether the hair was forcibly removed
If the hair has been treated with chemicals
If drugs have been ingested

47. Review of Hair Analysis
Comparison
Identification
DNA
Collect Reference Samples

48. Questions?