Hair/Fiber Analysis

HISTORY
Hair:

The first theory of trichology (study of hair) was published in 1857 and introduced the possibility of classifying a person from their hair. However, the microscopic hair examination only became possible in the twentieth century.

In 1857, the beginning of the recognition of trichology was incited by a trichology report published in France  but the field itseld didn't grow until the twentieth century. In 1931, Professor John Glaister published "Hairs of Mammalia from the Medico-legal Aspect" established a reference foundation in this area of study, eventually followed by "Microscopy of Hairs: A Practical Guide and Manual" by John Hick, which described the possible use of hair examination in the work of forensics. The analysis of hair can narrow down the person's race, gender, hair color, etc.

Fiber

Fibers are considered "trace evidence" and although it doesn't have as much effect in narrowing down the culprit as hair will, it can be helpful if the  fabric has unique patterns or unique fiber. Traces of fiber is frequently left in the crime scenes, either from the clothes that the culprit had worn, or more likely, the traces of the victim being at certain places before death. 

 PICTURE AND LABELED PART OF COMPLETE HAIR

Layers:

The layers of hair can be grouped in three distinct layers; cuticle, cortex, and medulla.

Cuticle

• is the outer layer of the hair shaft
• looks like scales of a fish, cells overlap one another
• provides protection, flexibility, strength, and sheen

(picture of healthy cuticle)

Cortex

• lies below the cuticle
• the hair color is determined here by the melanocytes which consume melanin
• made of keranin protein
• most of the volume of hair

Medulla

• core of the hair
• 10% of volume
• may be absent in thin hair

Parts of Hair

Shaft

• Visible part of hair above scalp

Root and Bulb

• living portion of hair delved into the scalp
• Bulb controls the growth of hair

Papilla

• Empty area at base of bulb
• Nourishment is given to the hair from here

MAJOR TYPES OF FIBERS

• Cotton
• soft and absorbent
• short, fine and creamy white color(unless colored otherwise)

Hair/Fiber Lab work : (My drawing of cotton fiber under microscope)

Color: white and transparent

Features: single threads are spread everwhere, all are very thin and loosely packed

• Nylon
• very durable and can be used as seatbelts, tires, etc.
• high resistance
• stretches

Lab observation of Nylon

Color: black
Condition: frayed
Observation: webbed into a consistent pattern that seems to be hard to break
• Linen
• High absorbency
• good conductor of heat
• high luster
• Polyester
• low absorbency
• resist wrinkling
• durable
• Silk
• sensitive to dyes
• soft texture
• luminous

Lab work: Silk observation

Color: Gray

Observation: weaved simply, but frays at the end

• Wool
• Fire resistant
• Water absorbent
• Durable
• Sensitive to dye

Lab work: Wool Observation

Color: black

Tip: Separates

Features: No observable pattern, shaggy and separates into many directions; closely packed





Hair/Fiber Collection Technique

Hair:
1. Recover all hair samples from the scene with a pair of tweezers and store them in labelled envelopes.
2. Store the envelope into an even bigger bag to not lose these important evidences.
3.  If the hair is attached to things such as dried blood or glass, do not remove it but collect the entire thing.

Fiber:
1. Pick up the fiber and seal them in an envelope so that it won't go missing.
2. If the fiber is too small, tape the fiber sample so that they won't escape from cracks in the envelope.

Typical Hair/Fiber Analysis
A prediction can easily be made of the characteristics of the person by their hair by simply holding it under a microscope. Each race has their distinguishing feature of hair, and although they rarely match perfectly, if the features are the same then it is probably a safe prediction.

For example, in our lab we examined not only fibers but also strands of hair from different people.

Colored Hair

Color: brown or yellowish

Condition of tip: Cut, sharply diagonal

Observation: smooth, but the color is lighter in the middle.

The middle part of hair forms a webby pattern.

Asian Hair

Color: black

Condition of tip: flat and cut

Observation: smooth, lighter in the middle but almost solid color

African American Boy Hair

Color: black

Condition of Tip: rounded, brown

Features: The stem is thin, but the tip rounds and becomes thicker

Synthetic Hair

Color: brown

Condition of tip: rounded a little bit

Features: lighter in the middle but not by much, smooth and straight

We also looked at hairs that belonged to non-human beings.

Dog Hair

Color: gray and black

Condition of Tip: Cut

Observations: rough edges, light at someparts, webby at the

lighter spots and overall thicker than human hair

Cat Hair

Color: black

Condition of Tip: pointy

Observation: wihite in the middle and eventually flattens out, webby

If the researcher wishes to gain more foolproof data from these samples, a DNA test can also be conducted. The individual's hair can be used as evidence for the usage of illegal drugs. Although trace evidences aren't as reliable as blood analysis or fingerprints, it can be combined with other information to pose as evidence. The individual's health condition can also be identified by the presense of mercury in the hair.

Reliability of Hair/Fiber Crime Scene Data
The reliability of hair varies, and the miscalculation is likely to occur from colored hair, perms, etc. There are methods to de-contaminate the hair sample, but it only makes the image clearer, not having much effect on finding the true color of the hair, eventually leading to their race. The chemicals overlapping the hair shaft makes it challenging to use the hair as a reliable evidence. Consistency is not present in these tests. The numbers for the "age range" of the person also vary by the lab itself, because no national reference table is made to determine the person's age depending on the amount of mineral in one's hair.

Notable Case
In 1936, the wife of a NBC executive was found strangled with her pajama top in the bathroom of her home. The scene indicated that she had known her killer, and from lack of evidence a professional was brought in to examine the scene and collect evidence that may have been missed. There was only one evidence that was found, and it was a strand of white hair later tested as being horse hair. That day two furniture movers had delivered a horse haired couch and it was predicted that one of these two had paid her an early visit. The store was quickly identified for the couch's distinguishing features and the two men were interrogated til one of them had confessed to the murder. This was one of the first cases where hair analysis was used to convict a criminal.

http://www.ehow.com/about_6102496_forensic-science_-hair-fiber-analysis.html

http://www.lamasbeauty.com/beauty/articles/correa/what_is_hair.htm

http://www.maquillagemaven.com/2011/05/anatomy-of-hair.html

http://www.textilefurnishings.com/polyester-fabric.html
http://www.crime-scene-investigator.net/collect.html