Fiber Evidence Value?.

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Presentation transcript:

Fiber Evidence Value?

Fiber Sources Natural Synthetic or Manufactured Plant sources Animal Sources Rayon (1911) Nylon (1931) Dacron Polyester

Polymer The basic chemical structure of all synthetic fibers All polymers consist of repeating units called monomers Polymers are made by linking many monomers together.

Identification and Comparison The value of fiber evidence lies in the criminalists ability to trace its origin

Torn Garments or Fabrics?

Physical Properties Crimp Pliability Resilience Perform “Burn test”

Just a Few Small Fibers? Comparison Microscope

Morphology and Cross Sectional Shape Trilobal and Multilobed – Some trilobal examples appear below Round and dumbbell shape Some round examples appear below

Determine Chemical Composition of the Dyes The Next Step Determine Chemical Composition of the Dyes

Use a Visible Light Microspectrophotometer A Microscope Combined With a Computerized Spectrophotometer

Chromatography Can Be used to Analyze Dyes Thin Layer Chromatography is the method of choice

All Techniques Require a Side-by-Side Comparison The Value of the Techniques Lies in the Ability of The Analyst to Narrow a Fiber’s Origin to a Limited Number of Sources