It’s a Hairy Subject!
Hair is commonly found at violent crimes. The naturally protective covering, called the cuticle,
helps hair be resistant to chemical decomposition, making it subject to retrieval during the
investigation making this trace evidence easy to find. Forensic scientists can glean many pieces of
information from the composition of hair that may include: human vs. animal origin, animal
species, body origin (beard, head, armpit, pubic, etc.), drug use, and sometimes race.
Your job is to become a forensic hair expert so that you can testify in a court case. Part of this
journey to becoming an expert is to learn how to prepare hair and cuticle slides as well as
identifying the parts of the hair. You will also be able to classifying hair as human or animal.
Materials:
 Compound microscope
 Glass and plastic slides
 Slip covers
 Water
 Pipettes
 Scissors
 Clear nail polish
 Clear plastic tape
 Ruler
(tip)
(Root at
scalp)
Precautions:
Always carry a microscope with one hand on the arm and the other on the base.
Do not get nail polish on the lens.
Scenario:
Police were dispatched to a remote area outside of town where a partially clad body was
discovered. After the GBI crime-scene investigators arrived, photographed, and sketched the
scene, the medical examiner recorded the body temperature to estimate the time of death. Once
the investigation was complete, the medical examiner retrieved the body and returned to the
crime lab.
At the crime lab, the medical examiner found hair evidence that was not consistent with the
victim. She collected the sample, placed it in a bindle, bagged it and filled out the proper evidence
label that included the chain of custody. You, the hair expert, will retrieve the evidence, sketch, and
compare it to the hair samples of three suspects that have been detained in the case.
Procedure:
Part A: Examination of Human Hair
1. Pull one of your head hairs.
2. Join the proximal (bulb end) and distal ends together on a glass slide.
3. Add a drop or two of water to the glass slide and apply the slipcover. Remember to
allow the slipcover to touch the water before laying it down.
4.
5.
6.
7.
8.
Adjust the microscope on low power until the hair comes into focus.
Now move to medium power (10x) using the fine focus knob only.
Sketch the bulb, the shaft and the tip and label each component. (18 Points)
Determine the medulla pattern.
Move the magnification to high (40x).
a. Note the color and pigment distribution of the hair.
9. Calculate the medulla index using the given ruler (only if the medulla is present.)
Remember to divide the width of the medulla by the total width of the hair and
record your findings.
10. Repeat steps 2-9 with a hair that is a different color from another classmate, or one
you brought from home. (18 points)
a. Note if the hair has been dyed, bleached, etc.
11. Now choose a hair from another part of your body and repeat steps 2-9. (18 points)
Part B: Examination of Animal Hair
1. Select a rabbit and a cat hair to observe.
2. Repeat steps 2-9, making sure to observe and sketch the base, shaft, tip, and medulla
pattern, if available.
3. Now select a different animal hair to observe.
4. Below you will find a points chart.
a. Rabbit hair (Up to 10 points)
b. Cat hair (Up to 10 points)
c. Third hair (Up to 10 points)
d. Optional hair (Up to 5 points bonus if lab questions completed. Place optional
on a separate sheet of paper.)
Part C: Complete the lab questions. (16 points)
1.
2.
3.
4.
5.
Hair is primarily considered class/individual evidence? Why?
Hair is primarily made up of what type of polymer protein?
What do you think is the function of hair in animals?
What is the cortical fusi and where is it found in hair?
Describe the difference between a hair that fell out naturally and a hair that was
forcibly pulled out.
6. What is unique about the root of a cat hair?
7. The medulla index is helpful when determining whether a hair is animal or human.
Explain.
8. Name another difference between human and animal medulla.
9. Where in the hair are pigment granules found?
10. How fast does hair grow?
11. What keeps hair from decomposing quickly?
12. Hair is a type of trace evidence that is easily transferred. What characteristics do
you think attribute to this fact?
13. Discuss the difference between the distal and proximal end of hair.
14. What is significant about the root of cat hair?
15. Human hair has what type of cuticle? Draw it.
16. Compare rabbit and deer medulla? Draw it.
Part D: Making a cuticle cast. (Optional. Parts A-C must be completed first. Up to 5 bonus points)
1. Choose 2 hair samples, one human and one animal.
2. You are going to prepare the slide so that you can get two casts per slide.
a. Paint a portion of the slide just to the right of center with a thin coat of clear
fingernail polish.
3. Gently place the hair on the slide leaving one end off of the slide.
4. If doing a second cast, repeat steps 2 and 3 just to the left of center.
5. Wait a minimum of 10 minutes. Make sure that the slide is completely dry.
6. Once the slide is dry, pull the hair straight up off of the slide. Do this for both hair
samples.
7. View the slide under the microscope using the best magnification for your sample.
8. Sketch the cuticle and compare describing what you see.
Part E: Case Findings
You have now completed your lab training for hair. At this point you should be able to identify the
cuticle and cortex of hair, determine medulla pattern, create a cuticle cast, calculate the medulla
index, and identify the hair as human or animal.
You will be supplied with the hair sample that was extracted from the victim and a sample from
each of the suspects. Create a report on your findings. Were you able to link or eliminate any of the
suspects? Make sure to support you findings using information like color, medulla characteristics
and medulla index.