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 accidentThe 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 Vehicles1. 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

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

Collecting paint evidence 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