Hair Forensics Hair is physical evidence Forensic characteristics

  • Slides: 33
Download presentation
Hair Forensics

Hair Forensics

Hair is physical evidence • Forensic characteristics of hair: – Color – Structure –

Hair is physical evidence • Forensic characteristics of hair: – Color – Structure – Morphology • It is not possible to individualize human hair

Structure of Hair • Hair is an appendage of the skin – Hair grows

Structure of Hair • Hair is an appendage of the skin – Hair grows out of the hair follicle organ – The hair extends from the root embedded in the follicle, continues into a shaft and terminates at the tip end

Hair Identification • Important features: – Cuticle scale structure – Medullary index – Medullary

Hair Identification • Important features: – Cuticle scale structure – Medullary index – Medullary shape • Other features: color, length, diameter; distribution, shape, color intensity of pigments • Comparison microscope is an invaluable tool

Hair Shaft • Used for most intense examination • Composed of 3 layers –

Hair Shaft • Used for most intense examination • Composed of 3 layers – Cuticle – Cortex – Medulla

Cuticle • Outside covering of the hair – Makes hair resistant to chemical decomposition

Cuticle • Outside covering of the hair – Makes hair resistant to chemical decomposition and makes it able to retain structural features over time – Structure: • Overlapping scales that point towards the tip end of each hair • Different species have different scale patterns

Cuticle • View the cuticle with a: – Scanning electron microscope – Cast of

Cuticle • View the cuticle with a: – Scanning electron microscope – Cast of the hair’s surface and view under a compound microscope

Cuticle – Scale Patterns • 3 types of patterns – Coronal: small rodents and

Cuticle – Scale Patterns • 3 types of patterns – Coronal: small rodents and bats but rarely in human hairs – Spinous: mink, seals, cats, and are never found in humans – Imbricate: human hairs and many animal hairs

Cuticle – Scale Pattern • Rabbit

Cuticle – Scale Pattern • Rabbit

Cuticle – Scale Pattern • Deer

Cuticle – Scale Pattern • Deer

Cuticle – Scale Patterns • Human

Cuticle – Scale Patterns • Human

Cuticle – Scale Patterns • Dog

Cuticle – Scale Patterns • Dog

Cuticle – Scale Patterns • Cat

Cuticle – Scale Patterns • Cat

Cuticle – Scale Patterns • Mouse

Cuticle – Scale Patterns • Mouse

Medulla • Looks like the central canal running through a hair – More than

Medulla • Looks like the central canal running through a hair – More than half of the hair’s diameter – Medullary index: measure of the diameter of the medulla relative to the diameter of the hair shaft (fraction) • Humans: usually less than 1/3 • Most other animals: ½ or greater • Presence and appearance varies from individual to individual and even among the hairs of a given individual

Human Medullary Index 0. 53 nm 1. 59 nm

Human Medullary Index 0. 53 nm 1. 59 nm

Medulla • 4 ways to classify: – Continuous • Most animals, Some humans (Asians)

Medulla • 4 ways to classify: – Continuous • Most animals, Some humans (Asians) – Interrupted • Most animals – Fragmented • Humans – Absent • Humans

Medulla • Shape – Cylindrical shape: humans & many animals – Various shapes for

Medulla • Shape – Cylindrical shape: humans & many animals – Various shapes for some animals • Searchable database for 35 common animal hairs encountered in forensic casework

Medulla - Patterns • Rabbit

Medulla - Patterns • Rabbit

Medulla - Patterns • Deer

Medulla - Patterns • Deer

Medulla - Patterns • Human

Medulla - Patterns • Human

Medulla - Patterns • Dog

Medulla - Patterns • Dog

Medulla - Pattern • Cat

Medulla - Pattern • Cat

Medulla - Patterns • Mouse

Medulla - Patterns • Mouse

Hair Identification - Race • 1 st: Distinguish between animal vs. human • 2

Hair Identification - Race • 1 st: Distinguish between animal vs. human • 2 nd: Identify race – Asian: wider diameter than the hairs of the other racial groups, thicker cuticle, continuous and wide medulla, larger pigment granules

Hair Identification - Race • African: largest pigment granules and are grouped in clumps

Hair Identification - Race • African: largest pigment granules and are grouped in clumps of different sizes and shapes. • Caucasian: evenly distributed pigment granules.

Hair Identification – Body Area • Head: uniform diameter and usually a cut tip

Hair Identification – Body Area • Head: uniform diameter and usually a cut tip • Pubic hair: coarse and wiry, exhibit considerable diameter variation or buckling, often have a continuous to discontinuous medulla

Root • Shows if hair was removed with force

Root • Shows if hair was removed with force

Can we tell if hair was dyed? • Yes! – Color will appear in

Can we tell if hair was dyed? • Yes! – Color will appear in cuticle and cortex – Bleach removes pigment – Estimate time since dyeing or bleaching: • Hair grows at approximately 1 cm per month

Damaged Hair

Damaged Hair

Special Characteristics

Special Characteristics

Collection & Packaging • Collect at least 50 full length head hairs from all

Collection & Packaging • Collect at least 50 full length head hairs from all over the scalp • Collect at least 24 full length pubic hairs from all pubic areas • Method: Pull hair out of skin, clip near skin line, or vacuum up

Forensics of Hair Analysis Hair Forensics Hair CanForensics of Hair Analysis Hair Forensics Hair Can
Forensics of Hair Analysis Hair Forensics One ofForensics of Hair Analysis Hair Forensics One of
Forensics of Hair Analysis Hair Forensics One ofForensics of Hair Analysis Hair Forensics One of
Hair and Nails Hair and Hair Follicles HairHair and Nails Hair and Hair Follicles Hair
Hair Structure Growth hair structure hair growth hairHair Structure Growth hair structure hair growth hair
2 2 Preserving Physical Evidence Forensics Physical Evidence2 2 Preserving Physical Evidence Forensics Physical Evidence
Trace Evidence Hair Analysis Trace Evidence Physical evidenceTrace Evidence Hair Analysis Trace Evidence Physical evidence
Hair as Evidence Form Structure of Hair HairHair as Evidence Form Structure of Hair Hair
Hair and Fiber Hair Evidence From hair oneHair and Fiber Hair Evidence From hair one
Hair Analysis Information from hair evidence Hair isHair Analysis Information from hair evidence Hair is
Hair and more hair Hair as Evidence CanHair and more hair Hair as Evidence Can
Trace Evidence Hair Forensic Science Hair is ATrace Evidence Hair Forensic Science Hair is A
Evidence Is hair Class or Individual evidence HAIREvidence Is hair Class or Individual evidence HAIR
Forensics Anthropology Forensics Anthropology What is Forensics AnthropologyForensics Anthropology Forensics Anthropology What is Forensics Anthropology
Forensics and Auditing Computer Forensics Computer forensics isForensics and Auditing Computer Forensics Computer forensics is
Forensics What is Forensics Forensics Science associated withForensics What is Forensics Forensics Science associated with
PHYSICAL EVIDENCE Physical Evidence Purpose of recognizing physicalPHYSICAL EVIDENCE Physical Evidence Purpose of recognizing physical
Forensic Science and Physical Evidence Forensic Science TheForensic Science and Physical Evidence Forensic Science The
Hair CHS Forensics Mr Mc Niff Hair GlossaryHair CHS Forensics Mr Mc Niff Hair Glossary
Lecture Forensic Evidence and Probability Characteristics of evidenceLecture Forensic Evidence and Probability Characteristics of evidence
Forensic Science An Introduction What Is Forensics ForensicForensic Science An Introduction What Is Forensics Forensic
Network Forensic Network Forensic Network forensics is aNetwork Forensic Network Forensic Network forensics is a
Hair Evidence Hairs as physical evidence Valuable becauseHair Evidence Hairs as physical evidence Valuable because
Hairs Trace Evidence Hair as Physical Evidence ClassHairs Trace Evidence Hair as Physical Evidence Class