Hair and Fiber Analysis Section (Wednesday November 30 2011)

John W. Hicks 

History of Hair and Fiber Analysis


Hair and Fiber analysis is an excellent method used by law enforcement officials and forensic scientists to identify criminals. It was established as an identification method in the 1900's. In 1977 John W. Hicks wrote Microscopy of Hairs: A Practical Guide and Manual in order to further assist forensics scientists in the future. As technology advanced, forensic scientists also began to perform DNA tests on the recovered hair samples in order to identify criminals. likewise, forensic scientists have used fiber comparison tests in order to identify inorganic hairs.

Since October 2002, the FBI has a database of over 1,800 hair and fiber samples.

Hair Diagram:

 

A Hair is comprised of three main parts:

1. The Cuticle: the outermost layer of the hair 

2. The Cortex: The layer in between the cuticle and medulla 

3: the Medulla: The innermost layer and core of the hair. 

Major Types of Fibers:

Polyester:

Polyester is a type of fabric which is commonly used in businesses for mass production such as: clothes, yarn, and general use in one's home. Most Polyester Fibers are thermoplastics which means they turn into a liquid when heated.

Wool:

Wool is unlike ordinary hairs; it grows in clusters, its crimped, and its elastic. Wool is commonly mass produced into sweaters and other clothes which makes it likely to be spotted in crime scenes.

Nylon:

Nylon is one the most commonly used fibers in the world. It was originally created in Feb. 28, 1935  by the DuPont Experimental Station. The mass production of this fabric makes it highly possible to be detected at a crime scene.

Cotton:

Cotton is a staple grown in regions around the world such as America, Africa, India, and Mexico. Cotton is commonly spun into yarn as shown in the picture. The vast amount of clothes made of cottom also makes it likely to be spotted in crime scenes.

 

Silk:

Silk is a very distinct fibre which comes from cocoons of the mulberry silkworm larvae. Some forms of silk can be woven into textiles to be mass produced, however, they are not very common which would allow investigators to easily track down the source.

Collection, Analysis, and Reliability of Hair analysis

Collection of Hairs and Fibers:

During an investigation, Hairs and Fibers are usually collected by using adhesive tape to collect the hairs from the crime scene. The collected hairs of fibers are then placed and labeled in a tube. If unable to use tape, the Forensice scientist may also use tweezers to collect the hair samples. Each sample will be placed in a bag and the sciencist will mark down the date, location, time, and his or her name. Another method of collection is vaccuming in which the crime scene is vaccumed with a filter to collect the hairs.

Analysis of Hair and Fibers:

After the Hairs and fibers have been collected from the crime scene, they are brought back to the lab for a forensic scientist to analyze them. Scientists commonly use Microscopes to determine the type of hair or fiber. Upon performing the analysis test, the scientist can determine the race of the person and also the company that manufactured the fiber.

Reliability of Hairs and Fibers:

The Use of hairs and fibers for forensic science has proven to be very reliable. For example, an organic hair from the murderer found at the crime scene can help determine his or her race. If the scientist uses a DNA test on the hair found, then they can conclude the identity of the murderer. In, addition,  an inorganic fiber, such as nylon, wool, etc. can be used to identify the muderer. Perhaps the murderer wore a wool sweater during the murder of an innocent victim; if the same wool from the criminal's sweater was found on the victim's body, then it would confirm the man as the criminal.

Famous Case Involving Hair Analysis:

The James Driskell Case of 1990

On 1991, James Driskell was wrongly convicted of a 1st degree murder involving the killing of Perry Harder. Harder was shot several times in the chest in 1990 and Driskell was sentenced to life in prison. There were three hairs found in Jame's van and the lab determined that they belonged to Harder. James spent over 10 years in jail for an incorrect conviction. The court case was not brought back until July 18th, 2006. During that time, forensic scientists used a DNA test on three hairs found on Harder's body at the scene of the crime. The forensic scientists concluded that the hairs did not belong to Harder. Afterward James Driskell was given 20,000 dollars to restart his new life.