19 D12. Geology and Health (Posters)

Sunday, 20 March 2022
1:30 PM - 5:30 PM
Freedom Hall A

USING STABLE ISOTOPES TO IDENTIFY CRIMINAL SUSPECTS

Paper number: 19-1
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Identification of trace evidence from a suspect or victim is instrumental to accurately linking a suspect to a crime. Hair is a common type of trace evidence but is largely class evidence in that color and texture are not individualizing characteristics. However, because no two people have the same diet, and because the δ13C and δ15N stable isotopic composition of hair is diet dependent, the determination of δ13C and δ15N in hair has the potential to play a pivotal role in individualizing hair samples. δ13C is influenced by amount and type of C3 and C4 plants consumed, whereas δ15N is influenced by the trophic level of organisms consumed. This study investigates the ability to distinguish between individuals’ hair samples via their isotopic composition. Samples were obtained from a diverse group of 8 subjects in Massachusetts. Samples were washed in a (2:1) methanol: chloroform solution, subsampled into tin capsules, and analyzed via EA/IRMS. ANOVA and Tukey’s range test were performed on the resulting dataset using PAST 3.0 (Hammer et al, 2012). ANOVA suggested that both δ13C and δ15N had significant differences between means of individuals (p <1×10-4). 43% of possible comparisons between individuals were significantly different in δ13C, and 50% were significantly different in δ15N. These results seem to indicate that, within a region, diet is the principal factor influencing the degree of individualization of hair samples and may have a valid application to forensic investigations. Future studies could include larger and more geographically diverse subjects, as well as other stable isotopes of interest, namely δ2H, δ18O, and δ34S.

Geological Society of America Abstracts with Programs. Vol. 54, No. 3

doi: 10.1130/abs/2022NE-375108

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