Summary of Hair Analysis- Lesson 1 (Forensics)

Summary of "Hair Analysis - Lesson 1 (Forensics)"

This video serves as an introduction to Hair Analysis in forensic science, focusing on the importance of hair evidence, its characteristics, and how it is analyzed in criminal investigations.

Main Ideas and Concepts

• Importance of Hair in Forensics:
  • The average person loses 40 to 125 hairs per day, making it likely that hair will be left at crime scenes.
  • Hair evidence can provide valuable clues to investigators and help narrow down suspects.
• Functions of Hair:
  • Regulates body temperature.
  • Acts as a sensory organ.
  • Protects the body.
• Types of Evidence:
  • Hair can be class evidence or individual evidence depending on whether the Follicle is attached.
    • Individual evidence: Hair with Follicle (contains nuclear DNA) allows for identification of a single person.
    • Class evidence: Hair without Follicle (shaft only) can only narrow down suspects to a group.
  • Mitochondrial DNA can sometimes be extracted from the hair shaft but is difficult and less reliable for positive identification.
• Collection Methods:
  • Plucking, shaking, scraping surfaces.
  • Using adhesives to collect hair from clothing or other surfaces.
• Observation and Analysis:
  • Hair is analyzed macroscopically (with the naked eye) and microscopically.
  • Macroscopic features: length, color, curliness, texture.
  • Microscopic features: Medulla pattern, pigmentation of Cortex, Cuticle scale type, hair health.
  • The best tool for microscopic comparison is a Comparison Microscope, which allows side-by-side analysis of hair samples.
• Hair Anatomy:
  • Two main parts: Follicle (root containing nuclear DNA) and Shaft.
  • The hair shaft consists of three layers:
    1. Cuticle: Transparent outer layer made of overlapping scales; protects inner layers.
    2. Cortex: Middle layer containing pigment (melanin) responsible for hair color.
    3. Medulla: Core of the hair shaft; Medulla patterns vary and can be classified into four types:
       • Absent (no Medulla)
       • Continuous (solid line)
       • Interrupted
       • Fragmented
• Additional Forensic Applications:
  • The part of the hair closest to the scalp is the youngest.
  • Hair can be tested for toxins, drugs, and metals using neutron activation analysis, which can provide clues about poisoning or exposure to harmful substances.

Methodology / Key Points for Hair Analysis in Forensics

• Collect hair samples by:
  • Plucking
  • Shaking
  • Scraping surfaces
  • Using adhesives on clothing or objects
• Classify evidence type:
  • Check for Follicle to determine if nuclear DNA analysis is possible (individual evidence).
  • Without Follicle, treat as class evidence.
• Examine hair macroscopically:
  • Note length, color, curliness, texture.
• Examine hair microscopically using Comparison Microscope:
  • Observe Medulla pattern.
  • Examine pigmentation in Cortex.
  • Analyze Cuticle scale patterns and hair health.
• Consider hair anatomy:
  • Identify Follicle and shaft.
  • Understand the layers of the shaft (Cuticle, Cortex, Medulla).
• Use additional tests if necessary:
  • Neutron activation analysis for toxins/metals.

Speakers / Sources Featured

• Primary Speaker: Forensic instructor/lecturer (unnamed) delivering the lesson on Hair Analysis for forensic students.

This concludes Lesson 1 of Hair Analysis, with a promise of Lesson 2 covering further details in the next video.

Category

Educational

Video