The work of the forensic scientist can assist in answering questions in police investigations, such as reconstructing what happened, confirm or disprove statements from a suspect or a witness, test a theory, narrow the search for evidence, indicate how a crime has been committed, ascertain whether there is an association between a suspect and a scene or a victim. Some case work experience is presented to illustrate this assistance.
Animal Hair Structure and IdentiJcation (T. D. Moore, Wyoming Game and Fish Research Laboratory)
Examination and identification of animal fibers found during the investigation of crimes of violence between man or between man and animal have assisted in the successful prosecution of some of these crimes. A thorough understanding of hair growth, function, chemistry, and structure is a prerequisite for a criminologist to become proficient in hair identification. To this end, a brief review of the present knowledge of hair individualization is presented. The gross and fine structure of hairs as revealed by light and electron microscopy as well as chemical composition and relation to physical properties are reviewed. Growth and function of hair coats have limited forensic value but are also discussed.
A total of 12 characteristics have been used in identification of animal hair to family and genus. They are: color, shape, length, diameter, medulla configuration, pigment areas, strictures, basal configuration, tip configuration, scale patterns, scale margin types, and scale margin distance. Using these characters as well as artificial treatment (bleaching), damage (cutting), and other specialized structures, human hairs are separated to race and body area. Individualization of human hair has been less successful due to extensive hybridization among the population. Conclusions derived about human hair are threefold: unknown hairs are consistent with a given known sample, are dissimilar, or differences are not sufficient to draw a conclusion.
Pros and cons of other techniques for hair identification are discussed, but the methods of microscopy are still the only satisfactory procedures. Examples of cases involving animal hair identification at the Wyoming Game and Fish Research Laboratory are discussed.