Hairs Forensic Science http://media.popularmechanics.com/images/PMX0706FORENSICSHairSmall.jpg Presentation developed by T.
Hairs Forensic Science http://media.popularmechanics.com/images/PMX0706FORENSICSHairSmall.jpg Presentation developed by T. Trimpe 2006 http://sciencespot.net/ Graphic Organizer 1. 2. Hamburger fold your paper.
With the fold to the left side and the opening to the right, put the title on the front: Anatomy of Hair 3. 4. Open the paper out
and measure 2 inches down from the top of the long edge and draw a line. Measure 3 inches down from the line and draw another line. 2 inches 3 inches 3 inches
Hair Physical Evidence A good indicator of individual identity Resistant to chemical decomposition. Retains structural features over time Hair is not an absolute indicator of identity but can be a
good indicator of identity The Anatomy of Hair Hair is generally used as a class characteristic not an individual characteristic: Individual: can be related to a particular person or thing Class: can be related to groups of people or things
Using hair samples to ID a particular individual is very difficult unless the hair root is present. Biology of Hair Hair is composed of the protein keratin, which is also the primary component of finger and toe nails. Hair is produced from a structure called the hair follicle.
Humans develop hair follicles during fetal development, and no new follicles are produced after birth. Sources: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair & http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm#Index%20(Hairs) Biology of Hair Hair color is mostly the result of pigments. which are chemical compounds that reflect certain wavelengths of visible light. Sources: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair & http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm#Index%20(Hairs) Morphology of Hair
Three main regions: root, shaft, and tip Root: The part that was growing in the follicle. This is the widest part of the hair Morphology of Hair Shaft: The middle
of the length of the hair (from the root to the tip). This is where the hair tapers Tip: The end of the hair farthest away from the root. The hair is narrowest at the tip Front Page Graphic Organizer Hair Tip
Hair Shaft Sebaceous Gland Hair Follicle Hair Root Arrector Pilli Muscle Biology of Hair Hair shape (round or oval) and texture (curly
or straight) is influenced heavily by genes. The physical appearance of hair can be affected by nutritional status and intentional alteration heat curling, perms, straightening, etc. Sources: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair & http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm#Index%20(Hairs) Biology of Hair The body area (head, arm, leg, back, etc.) from which a hair originated can be determined by the samples length, shape, size, color, and other physical characteristics.
In order to test hair evidence for DNA, the root must be present. Sources: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair & http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm#Index%20(Hairs) Hair Structure Hair is composed of three principal parts: Cuticle outer coating composed of overlapping scales Cortex protein-rich structure around the medulla that contains pigment Medulla central core
(may be absent) The structure of hair has been compared to that of a pencil with the medulla being the lead, the cortex being the wood and the cuticle being the paint on the outside. http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair Hair Structure Graphic Organizer: Inside top left flap Cortex Largest part of hair shaft Contains most of the pigment granules (melanin)
The cortex varies in: Thickness Texture Color Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair Image: http://www.extrapersonality.com/hair.html Graphic Organizer: Inside top right side Hair Structure
Cortex Cuticle Medulla central core (may be absent) Hair Structure Cortex Distribution of the cortex is perhaps the most important component in determining from which
individual a human hair may have come. Microscopic examination can also reveal the condition and shape of the root and tip. Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair Image: http://www.extrapersonality.com/hair.html Hair Structure Graphic Organizer: Inside middle left side
Cuticle Transparent outer layer of the hair shaft Covered in scales that point toward the tip Made of scales Human : flat and narrow (imbricate) Animal : different types Hair Structure Graphic Organizer: Inside middle left side Cuticle The cuticle varies in:
Its scales, How many there are per centimeter, How much they overlap, Their overall shape, and How much they protrude from the surface Its thickness, and Whether or not it contains pigment. Hair Structure Graphic Organizer: Inside middle right side Imbricate Flattened Scales Coronal Crown Shaped Scales
Spinous Spiny Scales Hair Structure Characteristics of the cuticle may be important in distinguishing between hairs of different species but are often not useful in distinguishing between different people. Cuticle Man vs. Beast Human:
Tend to be unorganized and overlap like roof shingles from http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm from http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm Cuticle Photographs Coronal , crownlike scales Eg Bat Spinous or petal-like scales. Triangular in shape and
protrude from the hair shaft. Mink, Seals, Cats Never found in human hairs. Cuticle Photographs Imbricate or flattened-scales. consists of overlapping scales with narrow margins. They are commonly found in human hairs and many animal hairs. Hair Structure Graphic Organizer: Inside bottom left side
MedullaCenter of hair (Predominant feature of hair) Can be hollow tube or filled with cells: Can be absent Fragmented or segmented Continuous or doubled Pigmented or non-pigmented http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
http://www.bfro.net/images/whatis/figures/Fig.%203%20with%20caption.jpg Hair Structure Graphic Organizer: Inside bottom left side The medulla may vary in: Thickness Continuity - one continuous structure or broken into pieces Opacity - how much light is able to pass through it http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
http://www.bfro.net/images/whatis/figures/Fig.%203%20with%20caption.jpg Hair Structure Medulla Like the cuticle, the medulla can be important for distinguishing between hairs of different species, but often does not lend much important information to the differentiation between hairs from different people. http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair http://www.bfro.net/images/whatis/figures/Fig.%203%20with%20caption.jpg
Medullae in Human Hair Graphic Organizer: Inside bottom right side Continuous No breaks (duplicated) Interrupted Few short breaks
Medullae in Human Hair cont Graphic Organizer: Inside bottom right side Fragmented Few parts of the medullae visible Absent No medullae visible
Medulla Examples Photomicrograph of Animal Hair with vacuolated medullae. Photomicrograph of Deer Medulla with lattice-shaped medulla. The above examples have a well-defined appearance and came from a rabbit. Hair Identification Animal Versus Human Hairs
Human hairs are distinguishable from hairs of other mammals. Animal hairs are classified into the following three basic types (functions). 1. Guard hairs that form the outer coat of an animal and provide protection. 2. Fur or wool hairs that form the inner coat of an animal and provide insulation. 3. Tactile hairs (whiskers) that are found on the head of animals provide sensory functions. Human vs. Animal Hair Cat Hair
Human vs. Animal Hair Horse Hair Human vs. Animal Hair Dog Hair Human vs. Animal Hair Deer Hair Human vs. Animal Hair Rabbit Hair
Human vs. Animal Hair Human Hair Hair From Different Parts of the Body Varies from region to region of the same person. Six types of hair on the human body 1. 2. 3. 4.
5. 6. Head hair Eyebrows and eyelashes Beard and mustache hair Underarm hair Auxiliary or body hair Pubic hair Each has its own shape and characteristics
Life Cycle of Hair The root: provides for growth of old and new hair Three phases of hair growth: Anagen (up to 6 yrs): root attached to follicle for continued growth; root bulb is flame-shaped Catagen (2-3 weeks): slowed growth; root bulb has an elongated appearance Telogen (2-6 months): hair growth ends (becomes dormant) and is shed; root bulb is club-shaped (10-18% of hair)
Race Appearance Pigment Granules Cross Section Other
Generally straight or wavy Small and evenly distributed Oval or round of moderate diameter with
minimal variation Color may be blond, red, brown, or black Straight Densely distributed
Round with large diameter Shaft tends to be coarse and straight Thick cuticle Continuous medulla
Kinky, curly, coiled Densely distributed, clumped, may differ in size and shape Flattened with
moderate to small diameter and considerab le variation Picture Other Factors to Effect Hair European
Asian African Hair Comparison Highly subjective comparative test. DNA analysis of hair is a much more reliable testing technique
Nuclear DNA Analysis: DNA found in the nucleus of the cell Must have follicular tag or root structure present to test Mitochondrial DNA Analysis: DNA found in cellular material outside of the nucleus Can be tested without follicle or root structure More copies of mitochondrial DNA in cells Collection and Preservation Of Hair Evidence Must
be submitted with an adequate sample of hair from the victim of a crime, those entering a crime scene, or a suspect. Hair samples must be obtained from the same parts of the body. Usually involve head or pubic hair. Hair must be pulled out of the skin or by clipping it at the skin line. Hair is collected from the victims of suspicious deaths at autopsy.
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