ABSTRACT
From the physical evidence perspective, hair falls primarily within the category of associative evidence. The value of this type of evidence is primarily for comparison purposes in an attempt to associate individuals with objects, scenes, or other people. In general, hair makes good forensic evidence for several reasons: it is often lost unwittingly, it is relatively chemically and biologically stable, and the average human loses approximately 100 head hairs daily. The most useful hair comparison technique currently is morphological examination using light microscopy. However, while unequivocal exclusions are possible, when an adequate and representative known sample is available, our ability to associate a questioned hair with a known sample is limited with this approach. Evidence of cosmetic treatment is noted, when present, during the microscopic examination of a hair sample. On occasions in which the questioned and known samples exhibit similar treatments, detection and comparison of the nature of the treatment could be a useful adjunct to microscopic comparison. Similarly, a questioned hair can be excluded as coming from the donor of the known sample if the treatment histories are discernibly different.
