ETC ETC Laboratory Analysis & Forensic Science 2 — Questions and Answers
Question 1: Which microscopy technique is used to compare tool marks and bullet striations in forensic firearm analysis?
- Comparison microscopy (Correct answer)
- Scanning electron microscopy
- Phase contrast microscopy
- Darkfield microscopy
Correct answer: Comparison microscopy
A comparison microscope places two samples side-by-side in the same field of view, allowing direct visual comparison of tool marks or ballistic striations.
Question 2: What is the significance of a 'blank' sample in forensic laboratory analysis?
- It detects contamination by confirming no target substances are in the testing environment (Correct answer)
- It represents an unknown sample from the crime scene
- It serves as a duplicate of the primary evidence sample
- It calibrates the weight of the evidence package
Correct answer: It detects contamination by confirming no target substances are in the testing environment
A blank sample contains no target analyte and is processed alongside evidence to confirm the testing environment and reagents are not contaminated.
Question 3: Forensic DNA analysis uses STR (Short Tandem Repeat) profiling. How many STR loci does CODIS analyze?
- 20 core loci (Correct answer)
- 10 core loci
- 5 core loci
- 15 core loci
Correct answer: 20 core loci
The FBI's CODIS system was expanded in 2017 to include 20 core STR loci, significantly reducing the likelihood of a coincidental match.
Question 4: Which type of forensic analysis examines the unique characteristics of handwriting to compare questioned documents?
- Questioned document examination (QDE) (Correct answer)
- Latent print analysis
- Trace evidence analysis
- Ballistic fingerprinting
Correct answer: Questioned document examination (QDE)
Questioned document examination analyzes handwriting, typefaces, ink, and paper characteristics to determine authenticity or authorship.
Question 5: What laboratory accreditation standard do most US forensic labs seek to ensure quality and competency?
- ASCLD/LAB or ISO/IEC 17025 accreditation (Correct answer)
- FDA Good Laboratory Practice (GLP)
- Joint Commission accreditation
- OSHA 1910 compliance certification
Correct answer: ASCLD/LAB or ISO/IEC 17025 accreditation
ASCLD accreditation and ISO/IEC 17025 certification are the primary standards demonstrating that a forensic lab meets technical competency and quality management requirements.
Question 6: An evidence technician recovers a projectile from a crime scene. Which lab discipline would perform the analysis?
- Firearm and toolmark examination (Correct answer)
- Trace evidence analysis
- Serology
- Toxicology
Correct answer: Firearm and toolmark examination
Firearm and toolmark examiners analyze bullets, casings, and other projectiles to link them to specific weapons or determine trajectory.
ETC ETC Laboratory Analysis & Forensic Science 2
Which microscopy technique is used to compare tool marks and bullet striations in forensic firearm analysis?