Trace evidence can include small amounts of materials like hair, fibers, metals, paint, stains, inks, powders, insects, lipstick, makeup, and glass found at a crime scene. Examples of physical properties include color, odor and boiling point, while chemical properties determine how a substance changes into another substance. Analysis of various trace evidence like metals, powders, and paint can provide information about their physical and chemical makeup to help identify their source or introduction into a scene. In one 1912 case, analysis of the pink powder found under a suspect's fingernails matched the unique composition of the victim's face powder, leading to a confession.

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