Date of Submission

5-2026

Document Type

Thesis

Degree Name

Master of Science in Forensic Science

Department

Criminal Justice

Advisor

Alyssa L. M. Marsico, Ph.D.

Committee Member

Robert Powers, Ph.D.

Committee Member

Nikolas Stasulli, Ph.D.

Keywords

Hair, Crime Scene, DNA Analysis, Hair Proteins, Amino Acids, Gas Chromatography – Mass Spectrometry (GC-MS)

MeSH

Crime Scenes, Sequence Analysis, DNA, Amino Acids, Microscopy, Chromatography, Gas, Mass Spectrometry

LCSH

Crime Scenes, DNA Analysis, Microscopy, Amino Acids, Gas Chromatography, Mass Spectrometry

Abstract

Hair is an extremely common piece of evidence at a crime scene, due in part to its easy sheddability and persistence. Hair may be examined microscopically or analyzed by nuclear DNA analysis of the hair root. Microscopic hair examination has come under scrutiny in recent years for its subjectivity. Since hair proteins are relatively stable, it is possible to examine the ratios of amino acids in hair as a supplemental technique to distinguish hair of similar morphology. Morphologically similar medium brown hair from two donors was washed, cut, digested, derivatized and run in triplicate on a GC-MS instrument. The concentration of amino acid was determined using response factor with L-norvaline as an internal standard. Ratios were calculated of the concentration of amino acids between the two donors using a 3-ion SIM method and a scan method. The two individuals’ hair was able to be differentiated using 5 significant ratios in scan mode and 4 significant ratios in 3-ion SIM mode. The identity of these ratios were different for both modes, so it is recommended that future testing and implementation of this protocol use both modes to maximize sample comparison.

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