Forensic Paint Analysis

Forensic Paint Analysis

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.

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

Paint Layers on Vehicles 1. Electrocoat primer—applied to steel body of car, provides corrosion resistance, pigmented gray-black 2. Primer Surfacer—smooths out and hides seams or imperfections (different pigments) 3. Basecoat—color coat; different additives add different effects (pearl luster, metallic look) 4. Clear coat—unpigmented layer, improves gloss, durability, and appearance

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

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

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

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