Forensics Unit 6: Trace Evidence Quiz

Study Notes

Trace Evidence Overview

Trace evidence refers to physical evidence in small amounts found at a crime scene.
Examples include hair, fibers, paint chips, body fluids, stains, powders, and glass particles.

Unique Types of Trace Evidence

Uncommon traces such as torn paper, ashes, spider remnants, and match remnants can also be significant.

Physical and Chemical Properties

Physical properties are characteristics like odor, color, boiling point, and density that do not alter a substance's identity.
Chemical properties relate to how a substance transforms into another, revealing different physical traits.

Metal Analysis

Solid particles: examined microscopically for properties like magnetism and reactivity.
Dissolved metals: analyzed using chromatography to compare unknown samples with known ones.

Analytical Methods

Qualitative analysis employs sensory attributes (e.g., texture, color).
Quantitative analysis involves measurements (e.g., length, mass).

Product & Environmental Concerns

Product liability may arise from contaminants in products, determining if they originated from manufacturers or introduced by individuals.
Environmental contamination can stem from industrial activities affecting water and ecosystems.

Impressions and Patterns

Shoe impressions provide clues about size, brand, sex and weight of the wearer.
Different types of impressions include visible (patent), hidden (latent), and three-dimensional (plastic).
Impression databases (e.g., TreadMark) are used in forensic analysis.

Glass Characteristics

Glass is a hard, brittle material, primarily composed of silica.
Types of glass include soda lime (window glass), borosilicate (heat-resistant), and tempered (strong for safety).

Physical Properties of Glass

Density and refractive index are crucial in forensic analysis.
Density values vary across types, e.g., window density (2.46-2.49), lead glass density (2.9 - 5.9).

Refractive Index Measurements

Refractive indices of common substances: water (1.333), olive oil (1.467), and glycerin (1.473).
Changes in temperature affect refractive index readings, observable through the Becke line.

Fracture Analysis

Radial fractures radiate from the point of impact; concentric fractures appear as circles around it.
The 3R rule states radial cracks form right angles on the opposing side of the force.

Glass Fragment Collection

Proper collection involves separating fragments based on properties, labeling entry and exit sides, and packaging securely.

Description

Test your knowledge on trace evidence as covered in Forensics Unit 6. This quiz includes definitions, examples, and unusual types of trace evidence found at crime scenes. Perfect for students looking to reinforce their understanding of key concepts in forensic science.