Hairs and Fibers - Criminalistics Chapter Notes

These flashcards cover important concepts regarding the morphology of hair and fibers in forensic science, evidence collection, and DNA analysis.

What is the main role of hair in forensic science?

Hair serves as physical evidence in a variety of crimes and can provide strong corroborative evidence when properly collected.

What are the three layers of the hair shaft?

The three layers are the cuticle, cortex, and medulla.

What important feature does the cortex of hair contain?

The cortex contains pigment granules that give hair its color.

How is the medulla defined in terms of hair structure?

The medulla is a cellular column running through the center of the hair.

What are the three phases of hair growth?

Anagen (initial growth), Catagen (transition), and Telogen (final growth phase where hair falls out).

What is a follicular tag?

A translucent tissue found surrounding the hair's shaft near the root, which can be examined for DNA.

How can DNA help to individualize hair samples?

DNA analysis can be performed on nuclear DNA in the follicular tag or mitochondrial DNA in the hair itself.

What are the two main types of fibers?

Natural fibers (derived from animal or plant sources) and manufactured fibers (synthetic or regenerated materials).

What is the significance of the medullary index?

The medullary index measures the diameter of the medulla relative to the diameter of the hair shaft, which helps differentiate between human and animal hair.

Why is the comparison microscope essential in forensic analysis?

It is used to compare the morphological characteristics of hair and fibers.

What are variations in the medulla?

The medulla can be continuous, interrupted, fragmented, or absent.

What precautions should be taken when collecting fiber evidence?

Fibers should be collected using clean forceps and packaged carefully to avoid contamination.

What analytical methods are used for fiber comparison?

Infrared spectrophotometry, microspectrophotometry, and chromatographic separation for dye composition analysis.

What role does mitochondrial DNA play in hair analysis?

Mitochondrial DNA can provide corroboration but cannot individualize a hair due to its high frequency in populations.

Is it possible to determine the racial origin of a hair sample?

Yes, in some instances it can be determined.