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Human Hair Proteomics - Improved Evidence Discrimination

NCJ Number
Date Published
August 2014
23 pages
This report presents the methodology and results of a project that developed a method for obtaining potentially probative information from human hair shaft samples by analyzing their profiles of constituent proteins.

Project findings indicate that the use of proteonic analysis of hair samples obtained at crime scenes increases forensic analysts' ability to identify the human source of each hair sample. The project consisted of two parts. The first part determined whether hair from different individuals is distinguishable by means of shotgun protein profiling; and the second part of the project developed a set of prototypic peptides (obtained reproducibly in high yield) that could be used to distinguish hair samples in a streamlined fashion. The first phase of shotgun proteomic analysis revealed considerable variation in profiles of hair samples from Caucasian, African-American, Kenyan, and Korean subjects. Within these ethnic groups, prominent keratin proteins were distinctive for each group. Among Caucasian subjects, hair shafts from axillary, beard, pubic, and scalp regions had distinguishable profiles. Triplicate samples of scalp hair from eight pairs of twins were processed and subjected to shotgun analysis. Results showed that the twin pairs were distinguishable from each other; however, distinguishing the two twins of a given pair was more difficult, but not impossible. The project modified the original standard protocol for hair processing so as to permit analysis of small sample amounts. These protocol changes are described in detail. It is recommended that future research examine changes in hair composition due to aging, further characterize hair samples from different anatomic sites, and devise statistical methods for comparing and searching proteomic profiles. 6 figures, 3 tables, and 41 references

Date Published: August 1, 2014