Trace Evidence Flashcards
7 cards from real ETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Trace Evidence flashcards as text
Which analytical technique is most commonly used to determine the chemical composition and polymer type of fiber evidence?
Answer: Fourier transform infrared spectroscopy (FTIR)
FTIR produces a unique infrared absorption spectrum that acts as a chemical fingerprint for fiber polymers, allowing examiners to identify and compare fiber types.
When collecting soil samples as comparison trace evidence, what is the correct procedure?
Answer: Collect samples from multiple locations including control areas away from the scene
Collecting samples from multiple locations — including known control areas — allows forensic geologists to compare the questioned soil to reference samples and assess significance.
What microscopic index value helps differentiate human hair from most animal hair?
Answer: Medullary index
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.
What is gunshot residue (GSR) primarily composed of, and why is it significant as trace evidence?
Answer: Lead, barium, and antimony particles unique to firearm discharge
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.
Which tool is most appropriate for collecting dry, loose trace evidence such as glass fragments or paint chips from a surface?
Answer: Forceps or fine-tipped tweezers
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.
What forensic value do glass fracture patterns provide in a crime scene investigation?
Answer: They can indicate the direction and sequence of multiple impacts
Radial and concentric fracture lines, along with stress marks on fracture edges, can be used to determine the direction of impact force and the sequence in which multiple breaks occurred.
In trace evidence searches, which area of the crime scene should generally be examined first?
Answer: The most volatile area likely to be disturbed or where evidence could be lost
Volatile areas — those subject to weather, foot traffic, or environmental change — should be processed first to preserve fragile trace evidence before it is displaced or destroyed.