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Forensic Paint Analysis

Forensic Paint Analysis

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Forensic Paint Analysis

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  1. Forensic Paint Analysis

  2. How can paint tell a story?? • Able to associate an individual or vehicle with a crime scene • Hit and Run cases—dried paint/paint smears transfers to clothing or vehicle upon impact • Burglaries—paint can be transferred onto tools used to break into things • Can identify color, year, make, model of a car by paint recovered at an accident The vehicle involved in a hit-and-run of a bicyclist who later died left white paint chips at the scene.

  3. Composition • Paint is composed of a binder, pigments, and different additives • Most paint is applied in layers

  4. Paint Layers on Vehicles • Electrocoat primer—applied to steel body of car, provides corrosion resistance, pigmented gray-black • Primer Surfacer—smooths out and hides seams or imperfections (different pigments) • Basecoat—color coat; different additives add different effects (pearl luster, metallic look) • Clear coat—unpigmented layer, improves gloss, durability, and appearance

  5. How do we examine paint?? • Microscope • Compare questioned sample with control (known) sample side by side • Determine type of paint, • Look at surface texture, color, and color layer sequence • Layers—each layer of recovered sample is compared with corresponding layer of the control sample

  6. Paint chip left at a crime scene can be compared. Forensic scientist using a microscope to compare paint chips from a car involved in an accident with known samples of paint • Picture of paint comparison from hit and run Collecting paint evidence

  7. Malcolm Fairley “The Fox” • 1970s British Serial rapist • Detectives found yellow paint specks on a tree at one of the crime scenes • Paint analyzed—comes from a Austin Allegro car • Narrowed suspects—detective drove up at Malcolm’s house, found him cleaning a yellow Allegro • Examined car—found scratches on paint that matched paint flakes to the crime scene • Using this and other pieces of evidence, Malcolm was tried, convicted and sentence to 6 life sentences for rape, assault, and burglary

  8. Gary Ridgeway“Green River Killer” • 1970s and 80s—truck painter who killed in Seattle area • Killed between 50-90 women and dumped in Green River • Gary was suspected but never arrested • Killing stop and case goes cold • 2001—case is reanalyzed; paint on victims clothing matched to highly specialized paint used at Kenworth truck plant where Gary worked • 2002—using paint analysis as well as DNA analysis Gary is found convicted of 48 counts of murder and was sentenced to 48 life sentences