Hair/Fiber Analysis

History:



The importance of hair and fiber analysis and its significance in crime investigation was realized in the early stages of forensic science. In the early twentieth century, the trichology field expanded considerably once the examination of hair microscopically was discovered. Hair and fiber analysis is still widely used in forensics today and has helped solve numerous criminal cases since its discovery.

1857: The world was introduce to the idea that analyzing hair and fibers could be useful in identifying criminals through the publication of one of the first scientific report involving hair and fiber analysis (trichology) in France.

1899: Francois Goron, a forensic scientist, noticed one key detail of the unknown victim: their dyed hair. This discovery led the scientists to uncover the identity of the victim.

1910: The Hair of Man and Animals was published by forensic scientists Marcelle Lambert and Victor Balthazard, which includes many microscopic studies of hair from mammals.

1977: Professor John Glaister published his Hairs of Mammalia from the Medico-legal Aspect. It soon became a reknowned resource for hair and fiber analysis. Also, John Hick’s Microscopy of Hairs: A Practical Guide and Manual became an important tool for forensic experts because it laid out the groundwork for using hair examination as a form of police work.

Class Activity:

                                         A Complete Hair:

Major Types of Fibers:

Each type of fiber has distinguishing characteristics when viewed under a microscope:

Cotton:

Polyester:

Wool:

Nylon:

Silk:

 Collection Techniques:

During collection of hairs and fibers at a crime scene, each individual hair or fiber is its own peice of evidence. The most obvious technique for collecting hair and fiber is to pick it up with your bare hand and then placed in a safe location, if the specimen is large enough. Hairs can be put into envelopes (only if the envelope can be sealed) and then marked. If a hair is attached to another object certain steps have to be taken. For example,  if a piece of hair is attached to a small object, such as a shard of glass, then both the object and the hair are placed into an evelope as one piece of evidence and then marked. Consiquently, if the object is too large, then the area around the hair must be wrapped in paper to prevent loss of hair evidence. Tweezers can be used for removal of hairs or fibers if necessary, but hairs and fibers are most commonly picked up with someone's bare hands to be collected.

Analysis:

Both hairs and fibers are analyzed under a microscope, but their analysises help determine different things. Hairs help identify the race and relative age of a person. Also, the condition of the the root may help identify how the hair was removed from the body, whether it feel out, was ripped out, or was cut off.  DNA may be extracted from from a piece of hair to help identify the possible suspects/victims, as well. Contrarily, fiber evidence is analyzed to associate a suspect through statistical elimination. Fibers found at a crime scene must be able to be linked to a possible suspect.

Reliability:

Results bases soley off of hair and fiber samples is rarely considered definite, but this evidence is usually able to help form a significant lead in a criminal case. Statistical elimination ultimately can not be used as conviciton-worthy evidece, but is helpful in minimizing a list of suspects. Only DNA extracted from a hair sample is 100% reliable and conclusive.

Landmark Case:

One of the most famous cases using Hair or Fiber Analysis was the Atlanta Child Murders case. Victims were found in rivers wrapped in shower curtains, onto which several fibers were stuck. The fibers proved a perfect match to a very unusual carpet in the murderer's home, and after several tests, the criminal was pinpointed. The figures had gotten too tiny to leave room for the possibility of anybody else committing the crime. This was the first case in which the perpetrator was indentified solely off of fiber analysis.

In class, we completed and exercise where everyone had to observe and record the properties of a variety of hair and fiber samples such as Asian hair, Caucasian colored hair, dog hair, cat hair, synthetic hair, African American hair, wool, silk, cotton, and nylon. Each sample we obtained was put under a microscope so we could view the different characterisitcs of each sample.

Throughout this lab I learned that different hair and fiber types have very distinct characteristics when viewed through a microscope. For example, Asian hair was darker on the side, lighter in the middle, and very smooth. Contrarily, cat hair  had a braided pattern and was black on the outside, but colorless in the middle. I learned that each type of fiber has a distinct pattern, such as braided, frayed, and quilted. This lab proved that hair and fiber analysis is very useful during investigations and it is a reliable source when trying to identify the possible suspects of a crime

Sources:

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

http://www.ehow.com/about_5640929_forensic-science-hair-fiber-identification.html

http://www.thorne.com/altmedrev/.fulltext/6/5/472.pdf