1. How can hair be helpful in a CSI?
Objective: SWBAT explain the various parts of a hair
Do Now:
Would hair be classified as individual evidence or class evidence? Why?
How can hair be helpful in a CSI?

2. Announcements
45 minutes- Grades catch up

4. 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

5. Hair Structure Cuticle Scales Varies with species
Every human has an identical cuticle
Info: Image:

6. Hair Structure Cortex Texture Color Protein Keratin – strength
Info: Image:

7. The Cortex Contains pigment that gives your hair it’s color
The absence of this pigment makes hair…..?

8. 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.

9. Chapter 5
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
Kendall/Hunt

10. Recruitment Project 1. Set up 2. Name and Case Number
3. Recruitment Grade (20)
15 pts

11. Hair and the Crime Scene
Day 2
Hair and the Crime Scene

12. Hair and Fibers at the Crime Scene
Investigators consider these to be “trace evidence”

13. 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

14. 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

15. 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

16. Why do Fibers Have to Go Through So Many Tests?
So many of the same fibers are found on a lot of textiles

17. 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.

18. 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.
Fibers under a microscope
Cross-section of a man-made fiber
Images:

19. Fiber Transfer
Primary Transfer
Secondary Transfer

20. Primary Transfer AKA “direct transfer”
Fiber transfers from a fabric source like a carpet, bed, or furniture at a crime scene

21. Secondary Transfer
Already transferred fibers on the clothing of a suspect transfer to the clothing of a victim

22. Does Fiber Transfer Always Occur?
NO!!
Certain types of fabrics do not shed well

23. Fiber Analysis
Various tests can be performed on fibers to determine their properties.

24. 1. Burn Test
Fibers burn differently, produce different odors when burned, and have different ash/residue appearances

25. 2. Thermal Decomposition
When fibers are gently heated, they often break down/ decompose into their simpler units

26. 3. Chemical Tests
Solubility and chemical decomposition properties are different based on fabrics are made of.

27. 4. Microscopic Examination
Getting a closer look at a fiber under a microscope to determine it’s properties

28. 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?
What type is the worst?