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Fibers as Trace Evidence

Fibers as Trace Evidence. Fibers. Fibers are EVERYWHERE! As you interact with others or the environment, fibers become attached to your body and clothes, and drop off into the environment from your clothing, etc. ***What principle is this demonstrating?***.  Locard’s Principle.

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Fibers as Trace Evidence

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  1. Fibers as Trace Evidence

  2. Fibers • Fibers are EVERYWHERE! • As you interact with others or the environment, fibers become attached to your body and clothes, and drop off into the environment from your clothing, etc. • ***What principle is this demonstrating?*** Locard’s Principle

  3. Fiber = the smallest unit of a textile material that has a length many times greater than its diameter. What is a fiber???

  4. Fibers can be classified as: • 1-Naturally occuring = found in nature (plants and animals) and not greatly altered in production • Examples: wool, silk, cotton, flax, hemp

  5. 2- Manufactured or man made = originate from natural materials such as cotton or wood and undergo much processing (cellulose containing) --Examples: rayon (first man-made fiber) and acetate

  6. 3-Synthetic = manufactured from synthesized chemical compounds (non-cellulose containing) --Examples: nylon, polyester, acrylic, etc

  7. Fibers as Evidence • A fiber can be spun with other fibers to form a yarn that can be woven or knitted to form a fabric. • The type and length of fiber used, the type of spinning method, and the type of fabric construction all affect the transfer of fibers and the significance of fiber associations. This becomes very important when there is a possibility of fiber transfer between a suspect and a victim during the commission of a crime.

  8. Fibers are everywhere . . . • Most textiles are mass produced . . . thus it is hard to trace a fiber to a specific source • Fibers can still be useful to create links among victims, suspects, and places. ***What type of evidence do we call this????*** Class Evidence

  9. Cotton fibers are the plant fibers most commonly used in textile materials Interesting Points on Fibers . . .

  10. The animal fiber most frequently used in the production of textile materials is wool, and the most common wool fibers originate from sheep.

  11. More than half of all fibers used in the production of textile materials are man-made. Cross-section of a man-made fiber

  12. How can forensic scientists examine trace evidence? • Compare . . .physically . . . . . .using microscopy . . . . . .chemically.

  13. Resources • Deslich, B., & Funkhouser, J. (2006). Forensic Science for High School: Teacher’s Edition. Iowa: Kendall/Hunt. • James, S.H., & Nordby, J.J. (2005). Forensic Science: An Introduction to Scientific and Investigative Techniques. 2nd Edition. New York: Taylor & Francis. • The Science Spot Website: http://sciencespot.net/Media/FrnsScience/hairIDguide.pdf.

  14. Filament Cross-Sections Synthetic fibers are forced out of a nozzle when they are hot, and then they are woven. The holes of the nozzle are not necessarily round; therefore, the fiber filament may have a unique shape in cross-section.

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