Trace Evidence

Define trace evidence

• A characteristic that does not involve a change in the identity of a substance,

• A characteristic that determines how a substance will change into another substance

• physical evidence found in small amounts at a crime scene.

• physical evidence found at a scene that connects a single person to the scene

Check the items that are considered unusual trace evidence. (check 2 answers

• hair

• Ashes

• a spider

• fibers

Use the flow chart of analysis of metals to determine which metal was found at the crime scene. The metal is magnetic, and turns green when it reacts with HNO2

• Al (aluminum)

• Fe (iron)

• Ni (Nickel)

• Fe and Ni (Iron and Nickel)

Tags

NGSS.MS-PS1-2

Use the flow chart of analysis of metals to determine which metal was found at the crime scene. The metal is not magnetic, floats and reacts (rxn) with NaOH.

• Al (aluminum)

• Mg (Magnesium)

• Cu (copper)

• Al and Mg (aluminum and Magnesium)

Tags

NGSS.MS-PS1-2

Small but measurable amounts of material found at a crime scene.

• trace evidence

• individual evidence

• Circumstantial evidence

Evidence that is transferred at a crime scene and often very small is called ​ (a)  

• trace evidence

• Indirect evidence

• Direct evidence

• class evidence

What kind of microscope is used to compare trace evidence to a control?

• Comparison microscope

• Electron microscope

True or False: The shaft of the hair is considered individual evidence in a trial.

• True

• False

Answer explanation

Scientists only say the hair has characteristics that "cannot exclude" an individual as its source.

True or False: All hairs on a person's head are identical.

• True. Hair is very simple.

• False. That's why 25 control hairs are collected for comparison.

Tags

NGSS.HS-LS3-2

True or False: The cortex may contain pigment granules.

• True. Melanin is found in the cortex of a hair.

• False. Pigment granules are only ever seen on the cuticle.