Hair as Evidence, Essay Example

Hair samples are one of the most important forensic pieces of evidence that are located at a crime scene.  Trace evidence of hair lends itself to DNA testing one of the most reliable ways of identifying hair samples in comparative analysis. The hair is structured into three main parts:  the root, the shaft and the tip.  The length and shape of the hair may be used to determine which part of the body it was derived e.g. eyebrows, scalp, beard etc.  The hair lends itself to microscopic analysis where it may be determined if the hair has been subject to any chemical treatment like dyes.  This may also result in the dye being identified. Scale patterns in the cuticle of the hair may be used to identify species e.g. animal or human origin. The comparison of the scale patterns and the Medullary Index. Nail polish is often used in the determination of obtaining scale samples for analysis. The most compelling evidence however is from DNA testing where both sex and genetic composition may be determined.

When looking at the shape of the hair, particularly in determination of whether animal or human, most human hair has no medulla and people of Mongol extraction have a continuous medulla. (Flynn, 2009). Hair is also important as evidence because of its toxicology. The hair often remains after other sources of evidence have decayed, decomposed or do not lend themselves to forensic analysis.  During the capture of Napoleon Bonaparte he claimed that he was being poisoned by his English captors.  His valet kept a lock of his hair and this later was subject to neutron activation analysis and it was discovered that the hair contained significant traces of arsenic indicating that he had indeed died of poisoning over a long period of time.

Hair lends itself to a great deal of different forensic tests with DNA testing being the most potent of these tests. Nevertheless, it is unlikely that such evidence will stand-alone and would need to be supported with other forensic analysis results.  An example being murders resulting from domestic disputes where on its own it has little relevance.

Works Cited

Flynn, K. S. (2009, 9 20). Trace Evidence: Hair. Retrieved 5 30, 2011, from Crime and Clues: http://www.crimeandclues.com/index.php/physical-evidence/trace-evidence/63-trace-evidence-hair