Date of Award

5-2017

Document Type

Honors Thesis

Degree Name

Bachelor of Science

Department

Chemistry

Advisor/Committee Chair

Kyle C. Doty

Committee Member

Igor K. Lednev

Abstract

Although hair is one of the most common and abundant types of evidence found at a crime scene, the current forensic analyses employed underutilize its full potential evidentiary value. Microscopy is the fundamental technique used to analyze forensic hair evidence, but even this routine and well-accepted method has limitations. In this study, non-dyed and dyed hairs from individuals varying in race, biological sex, and age, were analyzed using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. Through the incorporation of multivariate statistical analysis, spectra collected from dyed and non-dyed hairs were differentiated with high accuracy. After hair spectra were determined to be dyed or non-dyed, dyed hair spectra were successfully differentiated amongst themselves based on brand (or manufacturer) and dye color. The methodology developed here allowed for predicting whether an individual used a permanent hair dye, and then the brand and color of hair dye used, with at least 90% confidence. The high accuracy shown in this study illustrates the ease and robustness of coupling ATR FT-IR spectroscopy and multivariate statistics for forensic hair analysis, specifically for the analysis of dyed hairs. The use of spectroscopy for forensic hair analysis, as demonstrated by this proof of concept study, would advance the field of trace evidence as a whole, and can potentially be utilized to confirm conclusions drawn from methodologies employed currently, in turn leading towards increased individualization.

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