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True-TV Fibers

Published on Nov 18, 2015

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PRESENTATION OUTLINE

1.

CROSS TRANSFER

  • Person to person contact
  • Used to connect a suspect to a crime scene
  • Vice versa
  • Locard's Exchange Principle
Photo by Finite Improbability
2.

CLASS EVIDENCE

  • Fibers can't be individual evidence
  • Other facts are needed
  • Can make a link between 2 crimes
  • Ex. 2 Ohio murders in the 1980s
  • Fabrics are mass produced
Photo by Hkuchera
3.

ROBERT BUELL

  • A 28-year-old was abducted
  • When she escaped, she reported who her kidnapper was
  • The suspect's van had similar carpet fibers to that found on Kristin
  • That and other evidence convicted Robert Buell
  • It was orange carpet: only 74 yards sold
Photo by marie-ll
4.

GATHERING FIBERS

  • Usually by tweezer, vacuum, or tape
  • Clothing, drapery
  • Furniture, carpet
  • Wigs
  • Blankets, sheets, towels, etc.
Photo by Upupa4me
5.

NATURAL V. SYNTHETIC

  • Natural: from plants or animals
  • Ex. Wool, cotton, silk
  • Synthetic: man/lab made
  • Ex. Elastic, polyester, rayon
  • Made up of polymers
Photo by clisenberg
6.

FIBER COMPARISON

  • Usually few fibers on scene
  • Sometimes just one
  • Compared to fibers from suspect source
  • Ex. Suspect's home
  • Goes under side by side visual analysis.
Photo by LadyDragonflyCC - >;<
7.

MICROSCOPES USED

  • Compound microscope
  • Comparison microscope
  • Phase-contrast microscope
  • Scanning electron microscope
  • These are used to visually compare two fibers
Photo by r.nial.bradshaw
8.

SPECTROMETER

  • Invented by two German scientists in 1859
  • Separates lights into component wavelengths
  • Creates absorption lines
  • Specific wavelengths are absorbed depending on the molecule
  • This is used to identify different substances
Photo by jeferonix
9.

FACTORS COMPARED

  • Shape
  • Dye content
  • Diameter
  • Chemical composition
  • Microscopic appearance
Photo by khowaga1
10.

THE WILLIAMS CASE

  • Case had many holes
  • Fibers were the major evidence
  • Fibers matched Williams house
  • That makes four suspects, not one
  • Lack of other evidence caused him to be acquitted
Photo by Grant MacDonald

Kenzie Staber