HAIR AND FIBERS

Do Now:Would hair be classified as individual evidence or class evidence? Why?How can hair be helpful in a CSI?

Objective: SWBAT explain the various parts of a hair

Announcements45 minutes- Grades catch up

Parts of the HairCuticle- tough, clear outside covering for protection

Cortex- middle layer that provides strength and gives hair its color

Medulla- interior that provides flexibility

Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair Image: http://www.hairdressersus.com/micro/Image5b.jpg

Hair StructureCuticle

ScalesVaries with speciesEvery human has an identical cuticle CortexTexture Color

Protein Keratin strength

Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair Image: http://www.extrapersonality.com/hair.html

Hair StructureThe CortexContains pigment that gives your hair its color

The absence of this pigment makes hair..?Medulla

The medulla may vary in:Continuity - one continuous structure or broken into piecesVaries with species Varies with different races

It may also be absent in some species. http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair

Hair Structure

http://www.bfro.net/images/whatis/figures/Fig.%203%20with%20caption.jpg The MedullaMost humans have no medulla (except Native Americans and Asians, where medulla is usually continuous)

Types:InterruptedFragmentedContinuousStackedAbsentnot presentChapter 5Kendall/Hunt9Recruitment Project1. Set up

2. Name and Case Number

3. Recruitment Grade (20) 15 pts

Day 2Hair and the Crime SceneHair and Fibers at the Crime SceneInvestigators consider these to be trace evidence

12What Happens When Hair or Fibers are Discovered?First Investigators need to determine if it is human or animal

If its human, investigators need to narrow it down to a group of individuals who could be the suspects

What We Can Learn From Hair SamplesWhether or not the source is animal or humanRacial OriginLocation on the Sources BodyWhether the hair has been chemically treatedColor Whether the hair was forcefully removed

Hair as a Chemical IndicatorYour 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 hairWhy do Fibers Have to Go Through So Many Tests?So many of the same fibers are found on a lot of textilesMany different natural fibers that come from plants and animals are used in the production of fabric. http://www.fireflydiapers.com/articles/diaperarticle_naturalfibersabsorb.htmCotton 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. Natural Fibers

Images: http://www.trashforteaching.org/phpstore/product_images/YarnWS.JPG http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm#Fiber%20Evidencehttp://www.jivepuppi.com/images/fiber_evidence.jpgMore 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 fiberSynthetic Fibers

Fibers under a microscopeFiber TransferPrimary Transfer

Secondary TransferPrimary TransferAKA direct transfer

Fiber transfers from a fabric source like a carpet, bed, or furniture at a crime scene

Secondary TransferAlready 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 wellFiber AnalysisVarious tests can be performed on fibers to determine their properties.

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

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

3. Chemical TestsSolubility and chemical decomposition properties are different based on fabrics are made of.

4. Microscopic ExaminationGetting a closer look at a fiber under a microscope to determine its properties

FIBER LABTake 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 youre wearing below your waist. Write in your lab book what fibers and hairs you think youll.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?