Objective: SWBAT explain the various parts of a
hair
Do Now:
Name 2 ways to determine the sex
of a skeleton.
2. How does your hair differ from the
person to the left or right of you?
3. Get out your brochure.
1.
Announcements
Grades:
Gloves: (optional)
Strand: yours and animal
Parts of the Hair
 Cuticle- tough, clear
outside covering for
protection
 Cortex- middle layer
that provides strength
and gives hair its color
 Medulla- interior that
provides flexibility
Hair Structure
Cuticle
•Scales
•Varies with species
•Cuticles in human look
the same
Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
Image: http://www.hairdressersus.com/micro/Image5b.jpg
Hair Structure
Cortex
•Texture
• Color
•Protein Keratin – strength
Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
Image: http://www.extrapersonality.com/hair.html
The Cortex
Contains pigment that
gives your hair it’s color
The absence of this
pigment makes hair…..?
Hair Structure
Medulla
The medulla may vary in:
•Continuity - one continuous structure
or broken into pieces
•Varies with species
•Varies with different races
• It may also be absent in some species.
http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
http://www.bfro.net/images/whatis/figures/Fig.%203%20with%20caption.jpg
The Medulla
 Most humans have no medulla (except Native Americans and
Asians, where medulla is usually continuous)
Types:
Interrupted
Fragmented
Continuous
Stacked
Absent—not present
Recruitment Project
 1. Set up
 2. Name and Case Number
 3. Recruitment Grade (20)

15 pts
Hair and the Crime Scene
Hair and Fibers at the Crime Scene
Investigators consider these
to be “trace evidence”
What Happens When Hair or Fibers
are Discovered?
 First Investigators need
to determine if it is
human or animal
 If it’s human,
investigators need to
narrow it down to a
group of individuals who
could be the suspects
What We Can Learn From Hair
Samples
 Whether or not the source is animal or human
 Racial Origin
 Location on the Source’s Body
 Whether the hair has been chemically treated
 Color
 Whether the hair was forcefully removed
Hair as a Chemical Indicator
 Your hair is capable of collecting materials that come
into your body via the blood stream and are delivered
to your hair root and deposited in the cortex
 Many drugs, vitamins, and poisons can be detected in
just a few millimeters of hair
Why do Fibers Have to Go Through
So Many Tests?
So many of the same
fibers are found on a
lot of textiles
Natural Fibers
Many different natural fibers that come from plants and animals are used in the
production of fabric.
Cotton fibers are the plant fibers most commonly used
in textile materials
The animal fiber most frequently used in the
production of textile materials is wool, and the most
common wool fibers originate from sheep.
http://www.fireflydiapers.com/articles/diaperarticle_naturalfibersabsorb.htm
Synthetic Fibers
More than half of all fibers used in the production of textile
materials are synthetic or man-made.
Nylon, rayon, and polyester are all examples of synthetic
fibers.
Cross-section of a
man-made fiber
Fibers under a microscope
Images: http://www.trashforteaching.org/phpstore/product_images/YarnWS.JPG
http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm#Fiber%20Evidence
http://www.jivepuppi.com/images/fiber_evidence.jpg
Fiber Transfer
 Primary Transfer
 Secondary Transfer
Primary Transfer
 AKA “direct transfer”
 Fiber transfers from a
fabric source like a
carpet, bed, or furniture
at a crime scene
Secondary Transfer
 Already transferred
fibers on the clothing of
a suspect transfer to the
clothing of a victim
Does Fiber Transfer Always Occur?
 NO!!
 Certain types of fabrics do not shed well
Fiber Analysis
 Various tests can be performed on fibers to determine
their properties.
1. Burn Test
 Fibers burn differently,
produce different odors
when burned, and have
different ash/residue
appearances
2. Thermal Decomposition
 When fibers are gently
heated, they often break
down/ decompose into
their simpler units
3. Chemical Tests
 Solubility and chemical
decomposition
properties are different
based on fabrics are
made of.
4. Microscopic Examination
 Getting a closer look at a
fiber under a microscope
to determine it’s
properties
FIBER LAB
Take several pieces of tape and press it against your shirt,
sweater, or
blouse.
 Rub it smooth and pull it off slowly and smooth it out on your
notebook paper.
 Repeat the procedure on your pants, skirt, or whatever you’re
wearing below your waist.
 Write in your lab book what fibers and hairs you think you’ll.
 Label the source of each sample and look at it under the
compound microscope.
 Sketch and label what you see.
 Classify the hair and fibers (cotton, nylon, pet hair, hair from
head, etc).
 Did you predict the outcome correctly?
 What type of fabric is the best collector?