Forensic Research: Hair/Fiber Analysis

History Of Hair and Fiber Analysis

Hair analysis began in France 1857 when scientist Edmond Locard discovered that people constantly transfer bits of dust, hair, fibers and other "trace" material without being conscious of it. Locard realized that these material exchanges could be invaluable to analyzing a crime scene. He even managed to solve a murder case he was investigating my telling the court that the victim had recently dyed their hair which lead to the tracking down of the criminal via identification of the hair sample.

His work became the foundation for fiber forensics for the early 1900s. Throughout fiber analysis’s history scientist have learned that drug usage shows up in hair samples allowing for poison identification leading them one step closer to catching a criminal. His principle of fiber transfer has helped forensic scientist across the globe identify criminals based off just the most minute sample of their clothing. Some of the most manufactured fibers that can be identified by forensics include polyester, nylon, olefin (mainly found in carpets), rayon and acrylic fibers.

Split Ends

When looking at hair the most commonly observed area is the shaft, it can be seen that it can be broken down into three main segments; the cuticle, the cortex and the medulla. The cuticle is the outermost layer composed of 6 to 11 layers of overlapping semi transparent scales that are responsible for hairs elasticity and waterproof qualities. People with thick or coarse hair will have more of these scales then a person with fine hair. The next layer is known as the cortex, it is the layer separating the cuticle and the cortex, this area of the shaft gives hair its flexibility, and perhaps more importantly it’s color. Forensic scientists can use this layer to tell if a hair has been treated to change color. Now to the core of the shaft is a honeycomb styled tube known as the medulla filled with air pockets.

Collection methods

When a crime is first investigated forensic scientists scan the area for any fiber traces left behind by carefully performing a grid search with tweezers and special sealing bags to prevent any cross contamination. While doing this they wear protective equipment to keep from contaminating any fibers. It is important to note that they do not use tape for fiber collection as it could crush and alter the fibers. In addition clothing of victims may also be inspected for evidence of unfamiliar fibers that could belong to the perpetrator. Other fiber samples may even be present under the fingernails of a victim.

Analysis

Typically hair and fiber analysis is done through the use of microscopy. A forensic scientist would analyze this information and then compare it to familiar known fibers until a match is found. If further analysis is required forensic scientists can extract DNA from hair samples in order to more accurately pinpoint the owner.

Through hair analysis it is possible to identify weather a hair had fallen out of natural cause or by force by observing the condition of the root. In addition gender can be observed through hair. Scientists however can most accurately determine drug usage from hair as residue is left behind for long periods of time after consumption. Race is also determinable via hair analysis as human hairs are broken down into three categories;

Caucasian- European in origin they are often straight or wavy in appearance, and exhibit colors ranging from blonde to brown to black.

Mongoloid- Asian origin they are regularly coarse, straight, and circular in cross section, with a wider diameter than the hairs of the other racial groups.

Negroid- Hairs African origins are often curly and have a flattened cross section.

Reliability

Even though much information can be obtained from hair/fiber analysis the evidence is not always conclusive. This is due to how few qualifying assessments there are that two strands of hair/fiber came from the same source. Fiber on the other hand has to be associated with a supposed source and therefore cannot be deemed 100% accurate. However DNA testing on hair can lead towards more accurate and traceable results.

InFamous Cases

In 1975 Police were baffled by over 30 murders having happened with no trace of a criminal. They finally found evidence pointing to Ted Bundy however before he could be punished he escaped to Florida where he committed three more murders. He was finally tracked down when the fibers of 12-year-old Kimberly Leach dress were found in his van later that year. He was sentenced to death.

Another serial killer eluded police for two years and twenty nine murders. Police eventually arrested Wayne Williams as he was driving away from the sound of a splash in an area where a body was recovered a couple of days later. Police didn't witness him drop the body, so their case was based largely on forensic evidence gathered from fibers found on the victims. There were multiple fiber evidences from his vehicle to his dog’s hair. In 1982 he was sentenced to life in prison for two murders even though Atlanta police believe he was responsible for at least 22 children murders.

Forensic hair and fiber analysis prevail yet again in 1983 when the bodies of two school boys (one tied by a rope that police couldn’t identify) were found. Police arrested a man who had been scouting a local school named John Joubert when scientists found a match between the unknown rope and a rope that the police found. Furthermore his a hair of one of the victims was found in John’s car.

Bibliography

http://www.ehow.com/about_5597295_forensic-analysis-hair.html

http://www.google.com/url?sa=t&rct=j&q=forensic%20hair%20analysis&source=web&cd=5&sqi=2&ved=0CFAQFjAE&url=http%3A%2F%2Fcourses.ncssm.edu%2Fbondell%2FForensics%2520documents%2FForensic%2520Hair%2520Analysis.ppt&ei=HyfATvD-DYzBtgfa56CzBg&usg=AFQjCNFJ89MSdPDPA6sVaDLhGHb9DhEFpw&cad=rja

http://www.centralreg.k12.nj.us/webpages/SHopson/files/hair.pdf

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

http://www.criminaljusticeschools.org/blog/10-famous-cases-cracked-by-forensics

http://www.microtracescientific.com/labratory/lineage/locard.htm

http://www.top-hair-loss-remedy.com/hair-structure.html

http://www.ehow.com/info_8546471_forensic-tools-techniques.html

http://encyclopediaegypt.com/eg-blond.htm