Chemical Make-up of Fiber FT-IR: –Fourier-Transform Infrared Spectro. –Absorption of Infrared light by the polymer that comprise fiber result in characteristic pattern –Non-destructive

FIBER MATCHES

Collection of Fiber Evidence Relevant articles of clothing packaged in paper bags –Items must be packaged separately to prevent cross contamination Any weapons with trace should be packaged correctly Collection of fibers using a tape-lift may be useful In the lab, several units may collaborate to analyze item –(ex: bullets containing trace)

Case File: Fibers on Scissors Sexual Assault Case Suspect used his scissors to cut off victim’s clothing Scissors recovered in search warrant

Case File: Fibers on Scissors Fibers tape-lifted off scissors Mounted and viewed microscopically Fibers from all victim’s clothing located: red acrylic, blue polyester and spandex (bra)

Paint Evidence General components of paint –Pigments and several additives suspended in a BINDER –Binder provides the medium for the pigments and is a polymeric substance

PAINT ANALYSIS Most important components of paint in forensic analysis: – color –Structure of different layers ** The most important physical property of paint analysis is layer structures ** Can be individualized to a single source if there is sufficient detailed layer structure

Automotive Finishing For Steel requires at least four organic coatings: –Electrocoat Primer –Primer Surface/ corrosion control –Basecoat/ provides color coat –Clear Coat/ improves gloss