Forensics Fibers
Published on Nov 19, 2015
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PRESENTATION OUTLINE
CLASS EVIDENCE
- Fibers are not as distinctive as hairs
- You cannot definitively name a fiber to a single source.
- Because of this, fibers can only be submitted as class evidence
SIGNIFICANT IMPACT
- While fibers cannot solve a case on their own, they do contribute.
- A murder investigation in Ohio was started because...
- The fibers did in fact link two murders and raise suspicions.
OHIO CASE
- Ohio investigation was started because...
- Distinct orange fibers were found on two different murder victims
- Some time later, another abductee escaped and led police to a van.
- van found to have similar orange carpeting
- Through further evidence, Robert Anthony Buell was convicted.
GATHERING EVIDENCE
- Fibers are collected using
- Tweezers
- Tape
- Vacuum
- Generally from clothing, wigs, carpeting, etc.
NATURAL V. SYNTHETIC
- Some fibers are natural
- ^from plants (cotton) or animals (wool)
- Some are manufactured
- ^synthetics (rayon, acetate, polyester)
- ...made from molecules called "polymers."
MICROSCOPIC ANALYSIS
- Microscopes provide
- Structure of a fiber
- Precise identification
- High resolution and depth focus
- Fully identifies a fiber with help from
SPECTROMETER
- Measures separation of light into wavelengths
- An analyst can read the spectrum of lines that absorb light
- Thus, different light intensities means different substance molecules.
- Combined with microscope= microspectrophotometer
- ^ provides magnified appearance and infrared reading.
PHYSICAL COMPARISONS
- Fibers are matched by physical properties
- These include: length and width of fiber
- And face-value color appearance.
CHEMICAL COMPARISONS
- Later, chemical properties are analyzed
- If dye is found on the fiber under microscopic analysis
- It can be extracted through Chromatography
- It also points to chemical components of fiber.
- Despite narrowing choices under analysis, fibers are still CLASS ev.
DISADVANTAGE
- Again, while powerful contributors of evidence
- Fibers on their own WILL NOT HOLD IN COURT!
- Overwhelming fiber evidence in Wayne Williams case
- was refuted as class evidence by Williams' Attourney
- And thus did not sway jury decision.
