Fibers Mr. McNiff CHSForensics. Introduction Fragments of cloth can have individual and or class...
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Transcript of Fibers Mr. McNiff CHSForensics. Introduction Fragments of cloth can have individual and or class...
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Introduction• Fragments of cloth can have
individual and or class characteristics.
• A fabric source can be verified when a portion of the material can be fitted physically with another piece of cloth.
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Introduction• Fibers can be transferred by
simple contact between two objects.
• Fibers can be found at points of entry, on rugs, couches, clothing, hats.
• Cloth is comprised of small threads which are composed of textile fibers.
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FIBER TRANSFER
• When fibers are transferred from the fabric of an individual's clothing to the clothing of another individual, it is called a primary transfer.
• As these same fibers are transferred to other objects during subsequent contacts, secondary transfers are occurring.
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Fiber Number• The number of fibers on the
clothing of a victim identified as matching the clothing of a suspect is important in determining actual contact.
• The greater the number of fibers, the more likely that contact actually occurred between these individuals.
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Fiber Location• Where fibers are found also
affects the value placed on a particular fiber association.
• The location of fibers on different areas of the body or on specific items at the crime scene influences the significance of the fiber association.
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• Fibers can be classified as–Mineral (glass, asbestos)–Animals (silk, wool, fur)–Vegetable (cotton, linen, hemp)–Synthetic (rayon, nylon, dacron, acetate)
Fiber types
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Synthetic fibers
(a) Acetate fiber. (d) Orlon fiber.(b) Nylon fiber. (e) Dacron
fiber.(c) Rayon fiber.
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Chemical analysis• Burn test– burning fiber may
give off a particular odor and leave a residue which is brittle, ash like, or a hard bead.
• Solvent/solubility test- determine if a fiber will dissolve in acetone, HCL, Sodium Hypochlorite.
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Chemical analysis• Stain test- checks to see if a
particular stain will adhere to the fabric/fiber
• Microscopic examination- the quickest, most accurate, and least destructive means of determining the microscopic characteristics of textile fibers.
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microscope• Should be used first to examine
fibers.• Physical features such as –Crimp–Length–Color
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microscope–Relative diameter–Luster–Apparent cross section–Damage–Adhering debris should be noted.
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Pictures• http://www2.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm• http://www.fantom-xp.com/wp_12_~_Hair_Neon.html• http://www.maine.gov/dps/msp/criminal_investigation/
crimelab/phymatch.htm• http://www. seedol.com• http://www. volpeenterprises.com• http://www. cakehead.com• http://www. topnews.in• http://www. whitecloud.co.uk• http://www. kaneva.com• http://www. eoa-co.com• http://www. alpinemeadowsguild.org• http://www. linenkids.com/page.html?id=15• http://www. hemptraders.com• http://www. whyfiles.org
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Pictures• http://www. ecouterre.com• http://www. ccmr.cornell.edu• http://www. source4style.com• http://www. micro.magnet.fsu.edu• http://www. home.gci.net• http://www. ymccoll.com• http://www. scienceclarified.com• http://www. sciencephoto.com• http://www. accessscience.com• http://www. labgallery.com• http://www. spsj.or.jp• http://www. tbc.school.nzReference• Sutton, James V. Forensics: the Search for Clues. West Chester, OH: Kemtec
Educational Corporation, 1997. Print.• Deedrick, Douglas W. "Deedrick - Forensic Science Communications - January
2004." FBI — Federal Bureau of Investigation. FBI — Federal Bureau of Investigation, Nov. 2004. Web. 23 Aug. 2011. <http://www2.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm>.