1. Trace Evidence

2. Trace Evidence
• physical evidence found in small amounts at a
crime scene
• Examples
▫ hair, fiber, metals, paint, stains, inks, powders,
insects, lipstick, makeup, glass particles and
soil

3. Chemical vs Physical Property
• Physical - A characteristic that does not involve
a change in the identity of a substance,
▫ Examples - odor, color, boiling point, density
• Chemical - A characteristic that determines how
a substance will change into another substance
with different physical properties
▫ Examples – rusting, combust

4. Metal Analysis
• Bits of metal can be identified from their physical
and chemical properties.
• Solid metal particles are found in a loaf of bread.
▫ Were they in the flour from the manufacturer?
▫ Or were they introduced by the plaintiff for
personal gain?

6. White Powders
• Given 10 white powders
• Must determine identity based on their physical
and chemical properties

7. Makeup
• In 1912, Emile Gourbin was suspected of strangling his
girlfriend, Marie Latelle.
• Gourbin was arrested but had an alibi.
• Edmond Locard went to Gourbin’s cell and removed
scrapings from under his fingernails.
• The scrapings contained tissue that possibly came from
Marie’s neck, but this was not provable.
• Locard noticed that the tissue was coated with a pink dust
• In the dust he found bismuth, magnesium, zinc oxide, and a
reddish iron oxide pigment called Venetian red.
• Examination of the face powder used by Marie revealed that
her powder was similar in composition
• In these days of mass-produced face powder, this evidence
would have far less significance.
• However, in 1912, because of the special preparation, it led to
the confession of Gourbin.

8. Inks or dyes
• Chromatography
▫ Stationary
▫ Mobile
▫ Chromatograph
• Used to separate inks or dyes

9. Paint
• Paint can be used as evidence in hit-and-run cases.
• New Cars – 4 layers of paint
▫ Primer – corrosion protection
▫ Primer
▫ Base coat
▫ Clear coat – protection, appearance, gloss
• Kind of car
▫ Make
▫ Model
▫ Year
House Paint
▫ Jimmy or tool
Art Forgery
▫ Verify or refute authenticity