ETC Trace Evidence 2

Question 1

Which analytical technique is most commonly used to determine the chemical composition and polymer type of fiber evidence?

Accepted Answer

Fourier transform infrared spectroscopy (FTIR)

Answer

FTIR produces a unique infrared absorption spectrum that acts as a chemical fingerprint for fiber polymers, allowing examiners to identify and compare fiber types.

Question 2

When collecting soil samples as comparison trace evidence, what is the correct procedure?

Accepted Answer

Collect samples from multiple locations including control areas away from the scene

Answer

Collecting samples from multiple locations — including known control areas — allows forensic geologists to compare the questioned soil to reference samples and assess significance.

Question 3

What microscopic index value helps differentiate human hair from most animal hair?

Accepted Answer

Medullary index

Answer

The medullary index (medulla diameter ÷ total hair diameter) is typically less than 1/3 in human hair and greater than 1/2 in most animal hairs, making it a key distinguishing feature.

Question 4

What is gunshot residue (GSR) primarily composed of, and why is it significant as trace evidence?

Accepted Answer

Lead, barium, and antimony particles unique to firearm discharge

Answer

The unique tri-element combination of lead, barium, and antimony in fused spherical particles is characteristic of primer discharge and is detectable on hands, clothing, and surfaces near a fired weapon.

Question 5

Which tool is most appropriate for collecting dry, loose trace evidence such as glass fragments or paint chips from a surface?

Accepted Answer

Forceps or fine-tipped tweezers

Answer

Forceps or tweezers allow the technician to pick up individual fragments with precision, avoiding contamination and maintaining the integrity of each piece of trace evidence.

(ETC) Evidence Technician Certification Practice Test

(ETC) Evidence Technician Certification Practice Test

ETC Trace Evidence 2