Questions and Answers
What is trace evidence?
Physical evidence found in small amounts at a crime scene.
Which of the following are examples of trace evidence? (Select all that apply)
What defines a chemical property?
What is qualitative analysis?
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What is quantitative analysis?
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What does environmental contamination refer to?
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What defines a patent impression?
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What characteristics of glass are typically analyzed?
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What does the 3R rule state?
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What is the refractive index of water?
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What is the significance of individual characteristics of glass?
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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.
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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.
