Fabric: is made of fibers Fibers: are “threads” and are considered class evidence Famous Case: Wayne Williams 1982 In this case, fibers were the almost the entire case. Williams was convicted of murder in 1982 based on carpet fibers that were found in his home, car and on several murder victims

 Although this case is unusual, fibers are generally considered of greater value as evidence than that of rootless hairs since they may contain a greater number of variables, thus showing more individual characteristics.

a. Synthetic u Polyester u Rayon u Nylon u Acetate u Acrylic u Spandex b. Natural u Silk (from cocoons made by larvae of silkworm) u Cotton u Wool (from hair of sheep) u Mohair (from hair of Angora goat) u Cashmere (from hair of Cashmere Goat)

a. Polymers: long chain of repeating chemical units. many (poly) units (mer) Monomer: the repeating units of a polymer By varying chemical structure of monomers with different chemical structures make polymers with different physical properties. Forensically they can be distinguished from one another.

 Are made from derivatives of petroleum, coal and natural gas Include: 1) Nylon--most durable man-made fibers; extremely light weight 2) Polyester-- most widely used man- made fiber 3) Acrylic--provides warmth from a lightweight, soft and resilient fabric 4) Spandex --extreme elastic properties

Polyester Fiber

C. How is it made? 1) Synthetic fibers are forced out of a nozzle (extruded) when they are hot, then they are woven. 2) Holes of nozzle not necessarily round; fiber filament may have a unique shape in cross-section.

a. Examples: Classified according to their origin: 1) Vegetable or cellulose 2) Animal or protein 3) Mineral Jute fiber Soy protein fiber Mineral fibers

1) Cotton--vegetable fiber. Strong, tough, flexible; moisture absorbent; not shape retentive 2) Ramie--vegetable fiber. Less flexible than cotton so often blended with cotton

1) Rayon--first man-made fiber; soft, lustrous, versatile fiber 2) Cellulose esters--cellulose is chemically altered to create entirely new compound not found in nature 3) Acetate--less expensive, less polluting than rayon

Ramie: FULLY natural Cotton: fully natural Rayon: Partly man made Acetate: partly Man made

Can you tell the difference(s) between the cotton on the left and the rayon on the right?

1) Wool--animal fiber coming most often from sheep but may be goat (mohair), rabbit (angora), camel, alpaca mink, vicuna, beaver. Wool Fibers ( 400X ) 2) Silk--animal fiber that is spun by a silk worm to make its cocoon; fiber reflects light and has insulating properties.

Cousin to the alpaca, llama and the wild guanaco, the vicuña weights approximately 100 pounds and stands just under three feet high at the shoulder. Vicuñas live in the extreme high- altitude regions of the Andes.

Now, the silky wool sits at the nose- bleed-high pinnacle of tailored luxury. Each year, only 13,000 to 17,500 pounds of vicuña become available to Loro Piana, a major purveyor of vicuña garments—a fraction of the 22 million pounds of cashmere the company works with annually. The Italian tailoring house Kiton makes only about 100 vicuña pieces a year; an off-the-rack sport coat costs at least $21,000.

1) Asbestos--a natural fiber that was used in fire- resistant substances (later found to cause cancer) 2) Metallics (mylar)--a manufactured mineral fiber 3) Fiberglass--another manufactured mineral fiber

Composed of individual threads or yarns, made of fibers, that are knitted, woven, bonded, crocheted, felted, knotted or laminated a. Individual Characteristics: -degree of stretch -absorbency -water repellence -softness -durability

b.Fabric usefullness: The more unique the fiber/fabric – more significance / Probative value in court T- Shirt material: typically not useful, too common

Microscopic observation 1) Color--compositional differences in dyes 2) Fiber surface--delustering particles that may be added by manufacturers 3) Comparison microscope used to check against known fibers

1) can be used to determine refractive indices of various fibers, 2) Measures bending of light as it passes from air into a solid or liquid Fluorescence – used to compare fibers and to spot fibers for collection

c. Dye Chromatography - gives a more detailed analysis of the dye composition > 7000 dye formulations d. Dyability is the way fabric accepts dye can be used to ID the sample e. Burning – observe how fiber burns, odor, color of flame, smoke, appearance of residue/ash

f. Thermal decomposition – gently heat to break down fiber to basic monomers g. Chemical tests – solubility, and decomposition h. Density – mass of object ÷ volume of object

i. Fourier Transform Infrared analysis (FTIR)—based on selective absorption of wavelengths of light

j. Pyrolysis gas chromatography-mass spectrometry (PGC-MS)—burns a sample under controlled conditions, separates and analyzes each combustion product Lines of A and B are the same, it’s a match!

a. Bag clothing items individually in paper bags. Make sure different items not placed on same surface before being bagged. b. Make tape lifts of exposed skin areas of bodies and any inanimate objects c. Removed fibers should be folded into a small sheet of paper and stored in paper bag

Man, I was nailed when those forensic guys found fibers from the kid’s math assignment in my teeth.