Fibers Mr. McNiff CHSForensics. Introduction Fragments of cloth can have individual and or class...

FibersMr. McNiff

CHSForensics

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.

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.

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.

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.

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.

• Fibers can be classified as–Mineral (glass, asbestos)–Animals (silk, wool, fur)–Vegetable (cotton, linen, hemp)–Synthetic (rayon, nylon, dacron, acetate)

Fiber types

Fiberglass

Asbestos

Silk

Wool

Fur

Cotton

Linen

Hemp

rayon

nylon

dacron

acetate

Synthetic fibers

(a) Acetate fiber. (d) Orlon fiber.(b) Nylon fiber. (e) Dacron

fiber.(c) Rayon fiber.

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.

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.

microscope• Should be used first to examine

fibers.• Physical features such as –Crimp–Length–Color

microscope–Relative diameter–Luster–Apparent cross section–Damage–Adhering debris should be noted.

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

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>.