ETC Laboratory Analysis & Forensic Science Flashcards

Which microscopy technique is used to compare tool marks and bullet striations in forensic firearm analysis?

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.

What is the significance of a 'blank' sample in forensic laboratory analysis?

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.

Forensic DNA analysis uses STR (Short Tandem Repeat) profiling. How many STR loci does CODIS analyze?

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.

Which type of forensic analysis examines the unique characteristics of handwriting to compare questioned documents?

Answer: Questioned document examination (QDE)

Questioned document examination analyzes handwriting, typefaces, ink, and paper characteristics to determine authenticity or authorship.

What laboratory accreditation standard do most US forensic labs seek to ensure quality and competency?

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.

An evidence technician recovers a projectile from a crime scene. Which lab discipline would perform the analysis?

Answer: Firearm and toolmark examination

Firearm and toolmark examiners analyze bullets, casings, and other projectiles to link them to specific weapons or determine trajectory.