Using δ13c And δ15n Stable Isotopes To Identify Suspects By Race/Ethnicity

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 δ14N stable isotopic composition of hair and fingernails are diet-dependent, the determination of δ13C and δ14N in hair has the potential to play a pivotal role in individualizing hair samples. δ13C is influenced by the amount and type of C3 and C4 plants in a diet, whereas δ14N is influenced by the trophic level of organisms consumed. This study investigates the ability to distinguish hair samples via their isotopic composition, and any possible influence of ethnicity on isotopic composition. Samples were obtained from 8 individuals of varying ethnicity (Black, White, Asian, and Hispanic) in Massachusetts.