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?

Announcements 45 minutes- Grades catch up

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 Every human has an identical cuticle 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

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

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

Hair and the Crime Scene Day 2 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. Fibers under a microscope Cross-section of a man-made fiber 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? What type is the worst?