(Ch 4) Fibers and Textiles “Wherever he steps, whatever he touches, whatever he leaves even unconsciously, will serve as silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool marks he leaves, the paint he scratches, the blood or semen he deposits or collects— all of these and more bear mute witness against him. This is evidence that does not forget.” —Paul L. Kirk (1902 – 1970) - - Forensic scientist

Chapter 6  FIBER: The smallest unit of a textile  Multiple fibers together make a thread  TEXTILES: A flexible, flat material made by interlacing threads (cloth) 2

Chapter 6 Fibers   Class (group) evidence   Common trace evidence   Can be characterized based on comparison of both physical and chemical properties

Chapter 6  EACH INDIVIDUAL FIBER IS VISIBLE  ALL FIBERS TOGETHER MAKE THE THREAD Eye of a needle with thread

Chapter 6 5 How Forensic Scientists Use Fibers Fiber evaluation can show Type of fiber Type of fiber Color Color Possibility of violence Possibility of violence Location of suspects Location of suspects Point of origin Point of origin

Chapter 6 6 Fibers at the Crime Scene  Can occur  When two people come in contact  When contact occurs with an item from the crime scene  Methods of transfer  Direct transfer  Ex: Carpet fibers transfer onto victim or suspect  Secondary transfer — Already transferred fibers transfer onto another party  Ex: Carpet fiber transferred from victim to his attacker

Chapter 6 How to collect Fiber Evidence   Tweezers, tape, or vacuum   Bag textile items individually in paper bags   Avoids cross contamination

Chapter 6 FIBER CLASSIFICATION 1) Natural fibers - Animal - Protein - Plants – Cellulose (carb/sugars) - Mineral - Minerals 2) Synthetic fibers – NOT made by nature   Rayon, Nylon, Acetate, Acrylic, Spandex, Polyester etc… 8

Chapter 6 9 Types of Fibers Synthetic   Rayon   Nylon   Acetate   Acrylic   Spandex   Polyester Natural   Animal   Silk   Wool   Mohair   Cashmere   Plant   Cotton   Flax   Mineral   Asbestos

Chapter 6 10 Fiber Classification —Natural Fibers Plant fibers (polymer cellulose) :  Absorb water  Insoluble in water  Resistant to harsh chemicals  Dissolvable only by strong acids  Becomes brittle over time

Natural Plant Fibers Cotton is the most common appearing having a ribbon-like shape with twisted fibers

Chapter 6 12 WILD COTTON

Chapter 6 NATURAL/SYNTHETIC COMPARISON 13Kendall/Hunt Publishing Company  Synthetic POLYESTER  Natural COTTON

Chapter 6 14 synthetic naturalnatural natural natural naturalnaturalnatural

Chapter 6 Linen  Flax Plant 15Kendall/Hunt Publishing Company

Chapter 6 Animal (Protein) Fibers   Wool—animal fiber coming most often from sheep, but may be goat (mohair, cashmere), rabbit (angora), camel, alpaca, llama, vicuna   Fur-mink, rabbit, beaver or muskrat   Silk—insect fiber that is spun by a silk worm to make its cocoon

Natural Animal Fibers Examined and identified microscopically

Chapter 6 18Kendall/Hunt Publishing Company Silk

Silk Fibers

Chapter 6 20 Spider silk textiles To produce this unique golden cloth, 70 people spent four years collecting golden orb spiders from telephone poles in Madagascar, while another dozen workers carefully extracted about 80 feet of silk filament from each of the arachnids. The resulting 11-foot by 4-foot textile is the only large piece of cloth made from natural spider silk existing in the world today.

Chapter 6 21 Close up of “spider rug”

Chapter 6 22 Spider spinneret

Chapter 6 Sheep wool 23Kendall/Hunt Publishing Company 2525

Chapter 6 Cashmere wool 24 Alpaca wool

Chapter 6 Angora wool (mohair) 25Kendall/Hunt Publishing Company

Chapter 6 26Kendall/Hunt Publishing Company VICUNA

Chapter 6 27 Mineral Fibers   Asbestos   Natural fiber that has been used in fire-resistant substances   Rock wool   Manufactured mineral fiber   Fiberglass   Manufactured inorganic fiber (from glass)

Chapter 6 NATURAL FIBERS  Animal (hair) 28Kendall/Hunt Publishing Company  Plant (cotton)  Mineral (asbestos)

Chapter 6 29 Synthetic Fiber Cross- Sections   Synthetic fibers are forced out of a nozzle   Holes of the nozzle have a unique shape in   Cross section examined microscopically

Chapter 6 30 Synthetic Fibers  Cross sections of nylon carpet fibers seen with a scanning electron microscope (SEM)

Chapter 6 31 Fiber Comparison Can you tell the difference(s) between the cotton on the left and the rayon on the right?

Chapter 6 32 Synthetic Fibers ( Made from derivatives of petroleum, coal and natural gas)   Nylon—most durable of man-made fibers; extremely light weight   Polyester—most widely used man- made fiber   Acrylic—provides warmth from a lightweight, soft and resilient fiber   Spandex—extreme elastic properties

Chapter 6 33 Fiber Classification —Synthetic Cellulose Fibers  Regenerated Fibers  Derived from cellulose  Rayon  Most common in this group  Imitates natural fibers, but stronger  Celenese ®  Found in many carpets  Polyamide nylon  Used in performance clothing

Synthetic Polymer Fibers Produced solely from chemicals Different monomer combinations form polymers Include nylons, polyesters and acrylics

Chapter 6 35 Textile Terminology   Yarn—continuous strand of fibers or filaments, either twisted or not   Warp—lengthwise thread   Weft—crosswise thread (“weft” and right)   Blend— fabric made up of two or more different types of fibers

Chapter 6 36Kendall/Hunt Publishing Company “Warp” and “weft”

Weave Patterns

Blue shirt comparison

Jeans comparison

Chapter 6 41 How to ID a fiber 1. 1.Microscopic observation (visually) Compound Scanning electron Polarizing light 2. 2.Burning—observation of how a fiber burns, the odor, color of flame, smoke and the appearance of the residue 3. 3.Thermal decomposition—gently heating to break down the fiber to the basic monomers 4. 4.Chemical tests—ability to be stained or dissolved

Chapter 6 How to ID a Fiber  Polarizing light microscopy  Identifies fibers based on specific wavelengths  Infrared spectroscopy  Instrument that measures light beam pattern emitted from material to determine its chemical structure 42

Fibers- beautiful & easy to photograph

Fiber Count Linen Lycra Viewer Microscope

Burn Testing of Fibers

Other Tests on Fibers Seizing – scrape off starch Acetate – dissolve in acetone Fiber Etch ® - dissolves cellulose Nitric acid – cotton, wool or blend?

Fibers You never know when they are watching!

Collect fibers Under a microscope, measure diameter & sketch each fiber with a written description Obtain crime scene evidence and compare to fibers from each suspect

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