OIC Forensic Science & Analysis 3 — Questions and Answers
Question 1: In forensic document examination, which technique is used to detect erasures or alterations on paper without damaging the document?
- Acid wash analysis
- Infrared reflectography and oblique lighting examination (Correct answer)
- Ultraviolet burning to reveal ink layers
- Mechanical scraping to expose underlying text
Correct answer: Infrared reflectography and oblique lighting examination
Infrared reflectography and oblique lighting reveal indented writing, erasures, and ink differences without physically altering the document.
Question 2: When performing a trajectory analysis for a gunshot, an inspector uses trajectory rods. What information do these rods primarily establish?
- The caliber of the projectile fired
- The angle and direction from which a projectile traveled (Correct answer)
- The distance between the shooter and the target
- The type of firearm used in the shooting
Correct answer: The angle and direction from which a projectile traveled
Trajectory rods inserted into bullet holes establish the angle and direction of travel, helping to reconstruct the shooter's position.
Question 3: A forensic toxicology report identifies a blood alcohol concentration (BAC) of 0.18% in a deceased individual. In Oregon, the legal driving limit is:
- 0.05%
- 0.08% (Correct answer)
- 0.10%
- 0.15%
Correct answer: 0.08%
Oregon, like all US states, sets the per se legal BAC limit for driving at 0.08%, meaning 0.18% is more than twice the legal limit.
Question 4: Fourier Transform Infrared Spectroscopy (FTIR) is most commonly used in forensic analysis to:
- Identify DNA sequences from biological samples
- Identify unknown substances by their molecular absorption patterns (Correct answer)
- Measure blood spatter velocity at a crime scene
- Determine the age of fingerprint deposits
Correct answer: Identify unknown substances by their molecular absorption patterns
FTIR produces a unique infrared spectrum acting as a molecular fingerprint to identify unknown drugs, fibers, paints, and other materials.
Question 5: Which chain of custody requirement is MOST critical when transferring biological evidence between an Oregon inspector and a forensic laboratory?
- Verbal confirmation between the transferring parties
- Signed documentation recording who transferred the evidence, when, and why (Correct answer)
- Photographing the evidence before and after transfer
- Ensuring evidence is transported in a marked vehicle
Correct answer: Signed documentation recording who transferred the evidence, when, and why
A signed, dated transfer log creates an unbroken documentary record that can withstand legal scrutiny and proves evidence integrity.
Question 6: In forensic fire investigation, a 'V-pattern' on a wall is significant because it indicates:
- The direction of wind flow during the fire
- The approximate area of fire origin due to upward heat movement (Correct answer)
- That an accelerant was used to start the fire
- Water damage from firefighting efforts
Correct answer: The approximate area of fire origin due to upward heat movement
A V-pattern forms as flames burn upward and outward from the point of origin, with the lowest point of the V indicating where the fire started.
Question 7: When collecting soil samples as forensic evidence from a scene, an inspector should collect control samples from:
- Only the immediate area around the suspect's footprints
- Multiple locations near and far from the crime scene for comparison (Correct answer)
- Directly beneath the body or primary evidence only
- Any publicly accessible soil database for the region
Correct answer: Multiple locations near and far from the crime scene for comparison
Control samples from various distances allow forensic geologists to determine whether soil found on suspects or items is consistent with the crime scene.
OIC Forensic Science & Analysis 3
In forensic document examination, which technique is used to detect erasures or alterations on paper without damaging the document?