Hair Comparison

Microscopic hair examination and analysis have been taking place for a long time, but it has been discovered that they have a very limited capability to accurately identify individuals. Traditionally, comparing human hair is based on a microscopic comparison of the evidentiary sample with a known sample from the defendant. Based on a comparison of major and secondary characteristics, the examiner formulates an opinion as to exclusion or consistency. Although previously used by investigative agencies, it is now uniformly recognized that microscopic hair comparisons do not constitute a basis for a definitive identification and in fact have led to wrongful convictions. The National Academy of Sciences found no scientific support for the use of hair comparisons for individualization in the absence of nuclear DNA. The advent of DNA, and particularly the mtDNA method, has changed the field of forensic hair analysis from a microscopic examination into a DNA analysis of the cells in the hair. More recent developments have taken the science a step further. Scientists have now discovered that there is indeed identifiable nuclear DNA in the strands of hair even without a root.