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Introduction to fibers

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This document discusses fibers as trace evidence in forensic science. It covers Locard's Principle of exchange, and describes different types of fibers including natural plant, animal, and mineral fibers as well as man-made cellulose and petroleum plastic fibers. Specific fiber types are given like cotton, wool, silk, asbestos, rayon, nylon, and polyester. The document notes that fibers can be observed and identified through a microscope.

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FORENSIC SCIENCE Fiber 1
Locards Principle Every contact leaves a trace. Anyone who enters the scene of a crime takes something from the scene with them and leaves something behind. 2
Trace Evidence: occurs when two objects come in contact with one another examples: Hair Fiber 3
Types of Fibers Classified according to origin: 1. Natural Plant Animal or protein Mineral 2. Man-Made 4
Natural: Plant Fibers Cotton Hemp Linen (Flax) 5
Natural: Animal Fibers Wool: animal fiber usually from sheep but can be goat (mohair,cashmere), rabbit (angora), camel, mink, beaver Silk: animal fiber that is spun by a silk worm to make its cocoon; fiber reflects light and has Wool Fibers (400X) insulating properties 6
Natural: Mineral Fibers Asbestos: a natural fiber that is used in fire-resistant substances Metallics (mylar) Fiberglass 7
Man-made: Cellulose Derived Fibers (Made from chemically treated wood pulp and cotton) Rayon Acetate 8
Man-made: Petroleum Plastics Fibers (Made from petroleum, coal and natural gas) Nylon: most durable man-made fabric; extremely light weight Polyester: most widely used man-made fiber Acrylic Spandex: extreme elastic properties 9
Fiber Observations 10
Man, I was nailed when those forensic guys found fibers from the kids math assignment in my teeth.

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Introduction to fibers

  • 2. Locards Principle Every contact leaves a trace. Anyone who enters the scene of a crime takes something from the scene with them and leaves something behind. 2
  • 3. Trace Evidence: occurs when two objects come in contact with one another examples: Hair Fiber 3
  • 4. Types of Fibers Classified according to origin: 1. Natural Plant Animal or protein Mineral 2. Man-Made 4
  • 5. Natural: Plant Fibers Cotton Hemp Linen (Flax) 5
  • 6. Natural: Animal Fibers Wool: animal fiber usually from sheep but can be goat (mohair,cashmere), rabbit (angora), camel, mink, beaver Silk: animal fiber that is spun by a silk worm to make its cocoon; fiber reflects light and has Wool Fibers (400X) insulating properties 6
  • 7. Natural: Mineral Fibers Asbestos: a natural fiber that is used in fire-resistant substances Metallics (mylar) Fiberglass 7
  • 8. Man-made: Cellulose Derived Fibers (Made from chemically treated wood pulp and cotton) Rayon Acetate 8
  • 9. Man-made: Petroleum Plastics Fibers (Made from petroleum, coal and natural gas) Nylon: most durable man-made fabric; extremely light weight Polyester: most widely used man-made fiber Acrylic Spandex: extreme elastic properties 9
  • 11. Man, I was nailed when those forensic guys found fibers from the kids math assignment in my teeth.

Editor's Notes

  1. 09/20/12
  2. Dr. Edmond Locard (18771966) was a pioneer in forensic science who became known as the Sherlock Holmes of France. He formulated the basic principle of forensic science: "Every contact leaves a trace". This became known as Locard's exchange principle. 09/20/12
  3. When examining with the microscope, note: Color Fiber surface texture Make an accurate sketch! 09/20/12