1. Fiber & Hair Analysis

2. Hair Evidence Hair is composed primarily of the protein keratin
Defined as slender outgrowths of the skin of mammals
Each species of animal possesses hair with characteristic length, color, shape, root appearance, and internal microscopic features that distinguish one animal from another

3. Variability exists in types of hairs found on body of an animal Humans
Head, pubic region, arms, legs & other body areas have characteristics that can determine their origin
Hair types include coarse outer hairs or guard hairs (finer fur hairs, tactile hairs [whiskers], & others that originate from tail & mane)

4. Value of hair as evidence depends on:
Types of hair recovered
Condition of hair
# of hairs found
Comparison of microscopic characteristics of questioned hairs to known hair samples helps determine whether a transfer may have occurred

5. Hair Morphology
Hair is an appendage of the skin that grows out of an organ known as the hair folicle
Grows from hair follicle
Root is embedded in follicle
Shaft has 3 parts
Cuticle
Cortex
medulla
Terminates at a tip end

6. Anatomy of a Hair
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8. Follicle
Hair is an appendage of the skin that grows out of a hair follicle.
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9. The follicle contains more than enough cells for simple DNA Analysis
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10. A single root contains sufficient DNA for analysis
The length of a hair extends from the root embedded in the follicle.
A single root contains sufficient DNA for analysis
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11. Root
The root and other surrounding cells in the hair follicle provide the tools necessary to produce hair and continue its growth.
When pulled from the head, some translucent tissue surrounding the hair’s shaft near the root may be found. This is called a follicular tag.
By using DNA analysis on the follicular tag, the hair may be individualized.
HAIR FIBERS AND PAINT

13. Cuticle Is the outside covering of hair
Gives hair resistance to chemical composition & stability (retaining features over a long period of time
Formed by overlapping scales that always point toward the tip end
Scale pattern is useful in species identification but not a useful characteristic for individualizing human hair
Variety of patterns formed by animal hair makes it an important feature for species identification

14. Human b) Dog c) Deer
d) Rabbit e) cat f) Horse

15. Cortex Main body of hair shaft The interior of the hair
It is embedded with pigment granules that give hair its color
Color, shape, distribution of the granules provide important points of comparison

17. Pigment granules are absent in grey hairs
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18. Medulla
Group of cells having appearance of a central canal running through a hair
Sometimes it is the predominant feature, occupying more than ½ the diameter (varies by species)
Medullary index is the diameter of medulla relative to diameter of hair shaft
Humans is less than 1/3
Other animals, value is ½ or greater

19. Presence & appearance vary between individuals & among the hairs in a given individual
Medulla patterns
Continuous
Interrupted
Fragmented
Absent all together
Human head hairs the medulla is usually absent or fragmented; rarely have continuous
Animal medulla is either continuous or interrupted

20. Shape of medulla Cylindrical: humans & many animals
Patterned shape: other animals
Ex. Medulla of cat resembles a string of pearls
Ex. Deer medulla is spherical cells occupying the entire hair shaft
CAT
DEER

21. HUMAN
DOG
RABBIT
CAT
DEER

22. Hair Growth
Regions of the body that are primarily used in forensic comparisons are the head & pubic areas
As hairs undergo cyclical growth ( anagen) & resting phase (telogen), the visible microscopic characteristics are sufficient to determine the phase of growth of the hair

23. Anagen phase Telogen phase Catagen phase Hair actively growing
Materials are deposited in hair shaft by cells found in follicle
Metabolically active & dividing cells above & around the dermal papilla of the follicle grow upward during this phase to form – medulla, cortex, cuticle, & root sheath
80-90% of hairs
Telogen phase
Follicle is dormant or resting
10-18%
Catagen phase
Transition period between anagen & telogen 2%

25. Hairs routinely lost during telogen phase & become a primary source of evidentiary material
Hairs can also become dislodged from the body while they are in an actively growing state (anagen)
Microscope appearance of root area will allow for the determination of growth phase

26. When pulled from the root, some anagen hairs will have a follicular tag
Is a translucent piece of tissue surrounding the hair’s shaft near the root
Contains the richest source of DNA associated w/hair

27. Naturally shed hair
- Displays undamaged, club shaped roots
Forcibly removed hair
- Will exhibit stretching & damage to root area
Forcibly removed hair w/tissue attached

28. Comparing Strands HAIR FIBERS AND PAINT
The comparison microscope is an indispensable tool for comparing the morphological characteristics of hair.
When comparing strands of human hair, the criminalist is particularly interested in matching the color, length, and diameter.
A careful microscopic examination of hair will reveal morphological features that can distinguish human hair from the hair of animals.
Scale structure, medullary index, and medullary shape are particularly important in animal hair identification.
HAIR FIBERS AND PAINT

29. Comparing Strands HAIR FIBERS AND PAINT
Other important features for comparing human hair are:
the presence or absence of a medulla
the distribution, shape, and color intensity of the pigment granules present in the cortex
The most common request is to determine whether or not hair recovered at the crime scene compares to hair removed from the suspect.
However, microscopic hair examinations tend to be subjective and highly dependant on the skills and integrity of the analyst.
HAIR FIBERS AND PAINT

30. Questions HAIR FIBERS AND PAINT
Can the body area from which a hair originated be determined?
Can the racial origin of hair be determined?
Can the age and sex of an individual be determined from a hair sample?
Is it possible to determine if a hair was forcibly removed from the body?
Are efforts being made to individualize human hair?
Can DNA individualize a human hair?
HAIR FIBERS AND PAINT

31. Hair Microscopy Done w/light microscopy Is a 2 step process Purpose
ID of questioned hairs
Comparison of questioned & known hairs
Purpose
To ascertain whether 2 or more individuals could have come into contact w/an object
Particularly useful in crimes of violence (homicide, sexual assault, & aggravated assault) where physical contact may have occurred

32. Value of hair evidence
Related to the variability of hair characteristics between individuals in the population
Factors that impact the reliability of a hair assoication
Experience
Training
Suitability of known hair standards
Adequacy of equipment

33. Hair and DNA HAIR FIBERS AND PAINT
Recent major breakthroughs in DNA profiling have extended this technology to the individualization of human hair.
The probability of detecting DNA in hair roots is more likely for hair being examined in its anagen or early growth phase as opposed to its catagen (middle) or telogen (final) phases.
Often, when hair is forcibly removed a follicular tag, a translucent piece of tissue surrounding the hair’s shaft near the root may be present.
This has proven to be a rich source of nuclear DNA associated with hair.
HAIR FIBERS AND PAINT

34. Hair and Mitochondrial DNA
Mitochondrial DNA can be extracted from the hair shaft.
Mitochondrial DNA is found in cellular material located outside of the nucleus and it is transmitted only from the mother to child.
As a rule, all positive microscopical hair comparisons must be confirmed by DNA analysis.
HAIR FIBERS AND PAINT

35. Collection and Preservation
As a general rule, forensic hair comparisons involve either head hair or pubic hair.
The collection of 50 full-length hairs from all areas of the scalp will normally ensure a representative sampling of head hair.
A minimum collection of two dozen full-length pubic hairs should cover the range of characteristics present in pubic hair.
Hair samples are also collected from the victims of suspicious deaths during an autopsy.
HAIR FIBERS AND PAINT

36. Steps in Hair Examination Process
Determine if hair in question is from animal or human
If from animal
Identify the type of animal (species, not specific animal)

37. Animal Hairs
Hairs can vary greatly in color & length on different areas of the body; therefore, you should collect reference samples from each area
Samples should contain:
Full length hairs
Combings & pluckings
If animal isn’t available for collection, a brush or comb used on that animal may be substituted

38. Animal hairs found at scene or on clothing may have come from a fur coat or pelt
Since these are usually artificially dyed & don’t have a root, it’s preferred that entire garment be obtained for suitable samples

39. Human Hairs
An individual sheds approximately 100 head hairs each day
Body area determination
Characteristics used
Length, shape, size, color, stiffness, curliness, microscopic appearance, pigmentation, medullar appearance
Hairs that exhibit microscopic characteristics shared by different anatomical areas are called body hairs
Include hair on upper legs, lower abdomen, and back
- Head & pubic hairs are used most for forensic work because there is a wide range of interpersonal variation in these types of hair

40. Head hairs Longest hairs on human body
Have uniform diameter and, often, a cut tip
Are subject to more alteration than hairs from other body areas

41. Razor-cut hair
Hair w/cut tip
Split hair

42. Alterations to natural appearance include Environmental alterations
Dyes, rinses, permanents, frosts
Environmental alterations
Excessive sunlight, wind, dryness
Because of potential for alteration, it is recommended that head hair samples be obtained as soon as possible from suspects & victims of crime
Samples obtained years after a crime are generally not suitable for meaningful comparison purposes

43. Known samples
Need a random sampling of hair from different areas of scalp
# of hairs required vary
General rule is to obtain at least 25 full-length hairs, which includes both plucked & combed, packaged separately

44. Pubic Hairs Not subject to as much change as head hairs over time
Therefore, a sample taken a year or more after a crime may still be suitable for a meaningful comparison
It’s recommended that known samples be collected ASAP
Samples should contain at least 25 full-length hairs taken from different areas of the pubic region

45. Characteristics Course & wiry in appearance
Considerable diameter variation or buckling (twisting of hair shaft)
Often have a continuous to discontinuous medulla
Tapered tips are common, but these hairs may also be abraded or cut

46. Hair showing buckling

47. Facial Hairs More commonly called beard or mustache hairs
Characteristics
Coarse in appearance
Have a triangular cross section
Heavy shouldering or troughs are observed under magnification
Wide medulla
Razor cut tip

48. Significance of association of facial hairs may not be as great as head & pubic hair associations

49. Limb Hairs Hairs from legs & arms Characteristics
Shorter in length, arc-like shape, often abraded or tapered at tips, pigment is generally granular in appearance, medulla is trace to discontinuous
Not routinely compared in forensic lab
There are differences b/t individuals, but they’re not considered sufficient to allow limb hairs to be of value for meaningful comparison

50. Fringe Hairs
Hair originating from areas of the body outside those specifically designated as head or pubic
Not suitable for significant comparison purposes
Examples
Neck, sideburns, abdomen, upper leg & back

51. Other body area hairs Not routinely compared
Presence may help corroborate information obtained during an investigation (just like limb & fringe hairs)
Examples
Axillary (underarm), chest, eye, nose

52. Racial Determination Head hairs are best for determining race
Head hair from infants can be difficult to analyze
Also, hairs from individuals of mixed racial ancestry may possess microscopic characteristic attributed to more than one racial group

53. Caucasoid (European) Fine to medium courseness
Generally straight or wavy in appearance
Colors range from blonde to brown to black
Hair shafts vary from round to oval in cross section
Have fine to medium sized, evenly distributed pigment granules

54. Mongoloid (Asian) Regularly coarse straight circular in x-section
Wider diameter than other racial groups
Cuticle is usually significantly thicker than that of Negroid or Caucasian hairs
Medulla is continuous & wide
Cortex contains pigment granules that are generally larger in size compared to Caucasian hairs
Have characteristic red appearance

55. Negroid (African) Regularly curly or kinky Flattened x-section
Can appear as curly, wavy or coiled
Pigment granules are larger than those in Mongoloid & Caucasian
Pigments are grouped in clumps of different shapes & sizes
Density of pigment in cortex may be so great as to make hair opaque
Shaft has variation or apparent variation in diameter
Buckling can be present
Hair shaft frequently splits along the lenght

57. Age & Sex
Age of individual cannot be determined definitively by microscopic examination of hair
However, appearance of certain hairs, such as those of infants & elderly individuals, may provide a general age
How?
Infant hair is generally finer & less distinctive in appearance
As one ages, hair can undergo pigment loss & changes in configuration of hair shaft to become much finer & more vaiable in diameter

58. Sex of individual is difficult to determine
However, longer treated hairs are more frequently encountered in females
If hair is forcibly remove, sex can be determined using follicular tag

59. Treatment & Removal
Presence of dyes or rinses can be identified through microscopic examination of hair
Head hairs grow at the rate of 1cm/month
Approximate time of treatment can be determined by measuring the length of untreated area
Direct, side-by-side comparison of color of question & known artifically treated hairs is typically conducted by hair examiner

60. Biological or Environmental Alterations
When hairs originated from a body in a state of decomposition, a dark band may appear near the root of the hair
Called postmortem root band

61. Conclusions
Several possible conclusions which can be reached from examination & comparison of human hair
Questioned hair exhibits same microscopic characteristics as know hair & is consistent w/originating from source of known hairs
Questioned hair is microscopically dissimilar to hairs found in known sample & cannot be associated to the source of known hairs
Similarities & slight differences were observed b/t questioned hair & known hair sample. No conclusion could be reached as to whether the questioned hair originated from same source as known hairs

62. When a hair exhibits same microscopic characteristics as hairs in known sample, a qualifying statement may be added
Hair comparisons are not a basis for absolute personal identification. It sould be noted, however, that because it is unusual to find hairs from 2 different individuals that exhibit the same microscopic characteristics, a microscopic association or match is the basis for a strong association

63. Significance of Hair Evidence
Depends on method of collection
Processing techniques used
Methodology of hair examination
Experience of hair examiner
Head & pubic hairs are generally viewed as more significant than hairs from other body areas

64. Certain case situations affect significance of identifying hairs
When a family member possibly involved in crime
Location, #, condition (forcibly pulled or burnt)
Involvement of victim’s associates
Dates, coworkers, other people who may have logical contact w/or access to victim &/or crime scene
Situations involving strangers have greatest significance

65. Hair affected by burning

66. Textile fibers Can place a suspect at the crime scene
Fibers can be exchanged between 2 individuals, between an individual & an object, & between 2 objects

67. Importance of fiber matched to a crime scene
When fibers are matched w/specific source, a value is placed on that association
Value is dependent on:
type of fiber
Location of fibers at crime scene or on victim
# of different fibers at crime scene
# of different fibers on the victim that match clothing of suspect

68. Fiber Evidence Fiber – smallest unit of textile
Length much greater than diameter
Can be naturally occurring or synthetic
Can be spun w/other fibers to form a yarn that can be woven or knitted to form a fabric

69. Fiber Evidence
The quality of the fiber evidence depends on the ability of the criminalist to identify the origin of the fiber or at least be able to narrow the possibilities to a limited number of sources.
Obviously, if the examiner is presented with fabrics that can be exactly fitted together at their torn edges, it is a virtual certainty that the fabrics were of common origin.
HAIR FIBERS AND PAINT

70. Fiber Evidence HAIR FIBERS AND PAINT
Microscopic comparisons between questioned and standard/reference fibers are initially undertaken for color and diameter characteristics, using a comparison microscope.
Other morphological features that could be important in comparing fibers are:
Lengthwise striations on the surface of the fiber
The presence of delustering particles that reduce shine
The cross-sectional shape of the fiber
Compositional differences may exist in the dyes that were applied to the fibers during the manufacturing process.
HAIR FIBERS AND PAINT

71. Transfer of Fiber Factors affecting transfer of fiber
Type of fiber
Length
Type of spinning method
Type of fabric construction
Can be transferred from
Clothing
Carpets
Bed
Furniture

72. Can be transferred directly (primary) or indirectly (secondary)
primary occurs when a fiber is transferred from a fabric directly onto a victim’s clothing
Secondary occurs when already transferred fibers on clothing of suspect transfer to clothing of a victim

73. Contact doesn’t always transfer fibers
Certain fabrics do not shed well (donor garment)
Some fabrics don’t retain fibers well (recipient garments)
Factors affecting retention
Construction & composition of fabric
Duration & force of contact
Condition of garment w/regard to damage

74. Methods For Fiber Comparison
The visible light microspectrophotometer is a convenient way for analysts to compare the colors of fibers through spectral patterns.
A more detailed analysis of the fiber’s dye composition can be obtained through a chromatographic separation.
Infrared spectrophotometry is a rapid and reliable method for identifying the generic class of fibers, as does the polarizing microscope.
Depending on the class of fiber, each polarized plane of light will have a characteristic index of refraction.
HAIR FIBERS AND PAINT

75. Collection and Preservation
The investigator’s task of looking for minute strands of fibers often becomes one of identifying and preserving potential “carriers” of fiber evidence.
Relevant articles of clothing should be packaged carefully in separate paper bags.
If it is necessary to remove a fiber from an object, the investigator must use clean forceps, place it in a small sheet of paper, fold and label the paper, and place the paper packet inside another container.
HAIR FIBERS AND PAINT

76. Types of Fibers HAIR FIBERS AND PAINT
Natural fibers are derived in whole from animal or plant sources.
Examples: wool, mohair, cashmere, furs, and cotton.
Man-made fibers are manufactured.
Regenerated fibers are manufactured from natural raw materials and include rayon, acetate, and triacetate.
Synthetic fibers are produced solely from synthetic chemicals and include nylons, polyesters, and acrylics.
Polymers, or macromolecules, are synthetic fibers composed of a large number of atoms arranged in repeating units known as monomers.
HAIR FIBERS AND PAINT

77. Natural Fibers Originate from plants or animals Common plant fibers
Cotton, flax (linen), ramie, rayon, sisal, jute, hemp, kapok (silky-cotton like substance), & coir (coconut fibers)
Common animal Fibers
Wool (usually from sheep), camel, alpaca, cashmere, mohair
End use of sheep’s wool dictates fineness or coarseness of fibers
Finer fibers used in clothing
Coarser fibers found in carpet
Fiber diameter & degree of scale protrusion are important characteristics

78. Cotton fibers

80. Wool fibers

81. Flax fibers Ramie fibers

82. Kapok fibers Hemp fibers

83. Cotton- Hemp Blend

84. Synthetic Fibers
More than ½ of all fibers used in production of textile materials are synthetic
Polyester, nylon, acrylics,acetates
Some originate from natural materials such as cotton or wood
Amount of production of particular synthetic fiber & its use influence the degree of rarity of a given fiber

86. Shape of synthetic fiber can determine the value placed on the fiber

87. Cross section of synthetic fibers

88. Cross section of different nylon fibers

89. Fiber Color
Influences value given to a particular fiber identification
Often several dyes are used to give a fiber a desired color
Individual fibers can be colored prior to being spun into yarn
Yarns can be dyed , & fabrics made from them can be dyed

90. Color can be applied to surface of fabric – as in printed fabrics
How color is applied & absorbed along length of fiber are important comparison charateristics
Color-fading & discoloration can also lend increased value to a fiber association

91. Fiber Number & Location
# of fibers on clothing of a victim identified as matching clothing of suspect is important in determining actual contact
Greater the # of fibers, the more likely that contact actually occurred
Location of fibers on different areas of body or on specific items at scene influences the significance of the fiber association

92. Fabric Type
How fabric is constructed affects the # & types of fibers that may be transferred during contact
Tightly woven or knitted fabrics shed less than loosely knit or woven fabrics
Fabrics composed of filament yarns shed less than fabrics composed of spun yarns.
Age of fabric affects degree of transfer
Newer fabrics may shed more readily because of an abundance of loosely adhering fibers on surface
Worn fabrics may have damaged areas that easily shed fibers
Damage to fabric caused during physical contact greatly increases the likelihood of fiber transfer

93. Fabric Source Determination
It is not possible to say positively that a fiber originated from a particular fabric
inability to positively associate a fiber w/a source in no way diminishes the significance of a fiber association

94. It’s very helpful to know frequency of occurrence f a particular fabric & fiber, or how many fabrics w/a particular fiber type & color exist, as well as who owns them
If manufacture is known, possibility exists that # of fabric units produced could also be obtained

95. Once a particular fiber of a certain type, shape, & color is produced & becomes part of a fabric, it occupies an extremely small portion of the fiber/fabric composition
Exception – white cotton & blue cotton fibers (blue jeans)

96. Fiber Transfer & Persistence
Depends on type of fabric, & nature & duration of contact
Transferred fibers are usually lost rather quickly – depends on type of fabric & movement after contact
Clothing of homicide victim would tend to retain transferred fiber for a longer period because victim is not moving

97. EMS, medical examiners & investigators must handle victim’s clothing carefully to minimize fiber loss
Fibers will be lost is if victim/suspect moves about, brush the clothing or wash it

98. Multiple fiber associations
Nature of contact
Can determine the # of fibers transferred & value placed on their discovery
Violent physical contact of an extended duration will very often result in numerous fiber transfers
Multiple fiber associations
Multiple fiber types found on different items of clothing or fabric from suspect, victim, or scene greatly increase the likelihood that contact occurred between those individuals & the scene
Each associated fiber is considered to be an independent event
Multiple associations undermine a coincidence defense

99. Fiber Evidence: Assigning Significance
Matching dyed synthetic fibers or dyed natural fibers can be very meaningful
Whereas, matching of common fibers, such as white cotton or blue denim cotton would be less significant
Discovery of cross transfers & multiple fiber transfers between suspect’s clothing & victim’s clothing dramatically increasesthe likelihood that these 2 individuals had physical contact

100. When a fiber examiner matches a questions fiber to a know item of clothing, there are only two possible explanations
Fiber actually originated from the item of clothing
Fiber did not originate from the item of clothing

101. In order to say that the fiber originated from the item of clothing
the clothing either had to be the only fabric of its type ever produced or still remaining on earth
Or the transfer of biers was directly observed
therefore, fibers examiners will conclude that the fibers could have originated from the clothing or that the fibers are consistent with originating from the clothing

102. Only way to say that a fiber did not originate from a particular item of clothing is to know the actual history of the garment or to have actually observed the fiber transfer from another garment

103. Paint HAIR FIBERS AND PAINT
Paint spread onto a surface will dry into a hard film that can best be described as consisting of pigments and additives suspended in the binder.
One of the most common types of paint examined in the crime laboratory involves finishes emanating from automobiles.
Automobile manufacturers normally apply a variety of coatings to the body of an automobile.
These coatings may include electrocoat primer, primer surfacer, basecoat, and clearcoat.
HAIR FIBERS AND PAINT

104. Methods For Paint Comparison
The wide diversity of automotive paint contributes to the forensic significance of an automobile paint comparison.
Questioned and known specimens are best compared side by side under a stereoscopic microscope for color, surface texture, and color layer sequence.
Pyrolysis gas chromatography and infrared spectrophotometry are invaluable techniques for distinguishing most paint binder formulations, adding further significance to a forensic paint comparison.
Crime laboratories are often asked to identify the make and model of a car from a small amount of paint and will make use of color charts for automobile finishes.
HAIR FIBERS AND PAINT

105. Collection and Preservation
Paint chips are most likely found on or near persons or objects involved in hit-and-run incidents.
Paper druggist folds and glass or plastic vials make excellent containers for paint.
Paint smeared or embedded in garments or objects require the whole item to be packaged and sent to the laboratory.
Uncontaminated standard/reference paint must always be collected.
Tools used to gain entry into buildings or safes often contain traces of paint, requiring the tool be collected, along with reference paint samples.
HAIR FIBERS AND PAINT