Unit 2 Study Guide: Hair Analysis23

Comparison Microscpe

A compound microscope that allowed the side-by-side comparison of samples, such as hair or fibers.

Cortex

The region a hair located outside the medulla that contains granules of pigment.

Cuticle

The tough outer covering of a hair that is composed of overlapping scales.

Gas Chromatography

A method of separating chemicals to establish their quantities.

Hair Follicle

The actively growing base of a hair that contains DNA and living cells.

Hair Shaft

Part of the hair above the follicle; contains mitochondrial DNA.

Isotope

Different forms of an element that differ from their atomic mass and number of neutrons.

Isotope Signature

Isotope fingerprint is a ratio of different isotopes found in an individual.

Isotope-ratio mass spectrometry (IRMS)

A technology that allows examiners to analyze ratios of isotopes each of oxygen, hydrogen, carbon, nitrogen, and sulfur.

Keratin

Type of fibrous protein that makes up that majority of the cortex of a hair.

Medulla

Central core of a hair.

Melanin granules

Particles of pigment found in the cortex of a hair.

Mitochondrial DNA

Genetic material in the mitochondria of the cytoplasm of a cell, only inherited from the mother.

Nuclear DNA

Genetic material in the nucleus of a cell

Neutron Activation Analysis (NAA)

Process that relies on determining the concentrations of elements in materials by creating radioactive decay paths that can be identified and used to date archaeological specimens, gunshot residue, arsenic in hair, and geographic locations.

Explain why hair serves as a valuable source of evidence. (characteristics, source of DNA, chemical testing)

Adheres to many surfaces, easily transfers to a victim or crime scene, tough outer coating, physical characteristics provide less evidence.

Hairs with an attached follicle or root, contains Nuclear DNA and it provides individual evidence without a root or follicle, contains mitochondrial DNA, reveals family relationships.

Gas Chromatography, Isotope Ratio Analysis

1800

1800- Scientists recognized the importance of hair analysis as trace evidence

Anagen

1,000 days, growing stage, 80-90%

Catagen

Hair stops growing, follicle reduces due to reduced blood supply, 2%

Telogen

dormant/resting hairs that are lost 10-18%

Follicle

papilla or area containing capillaries, contains DNA and blood vessles

Hair Shaft

Nongrowing part of our hair, contains mitochondrial DNA

1900

Comprehensive study of hair published in France, first use of the comparison microscope

2000

Innocence Project, OSAC, NIST, DOJ, changes to hair analysis findings.

Neutron activation analysis (NAA)

Advancement in hair analysis, creates radioactive decay paths

Isotope Ratio mass spectroscopy (IRMS) and liquid chromatography/ protein analysis

Like DNA, provides individual evidence

DNA analysis

Hair containing a follicle or root, individual evidence can be obtained.

chemical analysis

anything ingested or absorbed through skin, hair does readily decompose, can establish evidence, or obtained

microscopic analysis

low power compound, phase contrast microscopy, fluorescence microscopy, electron microscopy

macroscopic analysis

seen with naked eye

attached hair

leaves hair intact, diagram and note exact location, photograph the hair, package clothing (if dry) with attached hair

not attached hair

photograph in situ, use clean forceps, place hair into small box or glass vial, once in the lab, the hair can be removed.

H/N- Pigmentation

Human hair are usually one color along the length

H/N- Medullary index

ratio of the diameter of the medulla to the diameter of the entire bar

H/N- Cuticle

human scales are flattened and narrow

Types of hair

shape, length, diameter, texture, and color

hair from different parts of the body

head, eyebrow, eyelash, underarm, beard and mustache, body and pubic

treated hair

bleaching. dyeing, and determining PMI

ethic or ancestral differences

key physical characters, European, African, Asian