FIBER

TRACE EVIDENCE:

Cotton Fibers

http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm

DEFINITION:- Smallest unit of a textile material that has a length manytimes greater than its diameter- Used to manufacture cloth, carpet, paper, cardboard, rope, cord, string, doll hair fibers, wig hair, etc

Natural Types:Animal: -Wool from sheep most common

- also from goats, camel, alpaca, rabbit, mink

Plant: - Cotton most prevalent

- Also flax(linen), ramie, sisal, jute, hempExcrement:-Silk from silkworm (cellulose from

mulberry leaves)Mineral: - asbestos Wool fibers

http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm

MAN-MADE:-More than half of fibers are synthetic

- > 1000 manmade fibers currently manufactured- 21 generic classifications

Regenerated fibers: -machine made from natural materials like cotton or wood

- 1910 rayon, then acetate, triacetate

Synthetic fibers: -Most fibers manufactured are producedsynthetically from chemicals- 1939 nylon, then polyester, acrylic

-Shape or cross-section can determinevalue of that fiber; manufacturer specific

cross-sectional views of nylon carpet fibers as seen with a scanning electron microscope

Fibers as Evidence:

At the scene: - Collected with tweezers, tape, or vacuum- Generally from clothing, drapery, wigs,carpeting, furniture, blankets- More - Esp. in crimes involving personal contact, more likely to transfer than hair

Fiber Evidence in Lab:

1. Color2. Diameter3. Dye content:-analyzed with chromatography

-> 7000 different dye formulations- dye formulas are closely guarded trade secrets

4. Shape5. Chemical composition6. Fluorescence7. Microscopic appearance: Number of strands

Number of fibers/strandTwists of fibers, etc

8. Type of weave:

Plain Weave

weft and warp intertwine in an alternate fashion, produces a checker board effect

Twill Weave produces parallel diagonal ribs

Satin Weave

no distinguishable . twill line

Fiber Significance:

1. Not possible to say with certainty that a fiber originatedfrom a particular piece of clothing

2. The clothing would have to be the only fabric of its type ever produced OR still remaining on earth OR the transfer of fibers was directly observed

3. Still…..When clothing fibers of the suspect are consistent withfibers found on the victim, 2 conclusions may be drawn:either the fibers originated from the suspect ORthe fibers originated from another fabric source that notonly was composed of fibers of the exact type and color, but was also in a position to contribute those fibers through contact. Highly unlikely!

http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm

CASE EXAMPLES:

1. Wayne Williams: Atlanta

James Jackson Parkway Bridge: spansthe Chattahoochee River

2. Series of rapes and murders beginning 5/84 inTampa, Florida

Unusual Trilobal Carpet Fiber

Tampa Florida, 1984

• Starting May 1984• 10 Young Women Raped and Murdered• 1st Victim… found one bright red fiber,

thought to be from automobile• 2nd victim… same red fiber but also fibers

from second red vehicle carpet, strands of brown medium length Caucasian hair, and tire impressions showing two different tires on rear of medium to full sized auto

Tampa Continued

• 3rd victim… red fiber but sent to different examiner due to

• 4th victim… red fibers and brown Caucasian hair

• 7th single red fiber

• Finally ended with 10 linked murders but nothing to lead to killer

Tampa

• 17 year old riding bike home from donut shop

• Man leap from car knocked her off, blind folder her and took her to her apartment

• Sexually assaulted her for 2 days

Tampa

• She did every thing he asked

• Kidnapper started to like her

• He blindfolded her

• Put her in car

• Took her back near where he picked her up

• And let her out

Tampa, 1984

• She didn’t fit with the normal pattern

• Checked her for fibers anyway– Red fibers were everywhere

• She remembered two things– Saw the word “Magnum” on dash under her

blindfold

– Stopped at a ATM at 3 AM before letting her out

Tampa, 1984

• Only car named Magnum was a 1978 Dodge Magnum

• Got a list of customers using an ATM around 3 AM

• Only 1 name on both lists…– Bobby Joe Long

Tampa, 1984

• He Received 26 life sentences and the Death Penalty

• Red fibers in Long’s car matched fibers on 8 of victims

• Found hair in car the matched 6 of the victims

• Car had two different rear tires• Two different types of red floor mats in

car