Forensic determination of hair deposition time in crime scenes using electron paramagnetic resonance.

Autor: Shankar N; Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA., Guimarães AO; Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA.; Laboratório de Ciências Físicas, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ, Brazil., Napoli E; Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA., Giulivi C; Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA.; MIND Institute, University of California Davis Medical Center, Sacramento, CA, USA.
Jazyk: angličtina
Zdroj: Journal of forensic sciences [J Forensic Sci] 2021 Jan; Vol. 66 (1), pp. 72-82. Date of Electronic Publication: 2020 Sep 28.
DOI: 10.1111/1556-4029.14570
Abstrakt: Several types of biological samples, including hair strands, are found at crime scenes. Apart from the identification of the value and the contributor of the probative evidence, it is important to prove that the time of shedding of hair belonging to a suspect or victim matches the crime window. To this end, to estimate the ex vivo aging of hair, we evaluated time-dependent changes in melanin-derived free radicals in blond, brown, and black hairs by using electron paramagnetic resonance spectroscopy (EPR). Hair strands aged under controlled conditions (humidity 40%, temperature 20-22°C, indirect light, with 12/12 hour of light/darkness cycles) showed a time-dependent decay of melanin-derived radicals. The half-life of eumelanin-derived radicals in hair under our experimental settings was estimated at 22 ± 2 days whereas that of pheomelanin was about 2 days suggesting better stabilization of unpaired electrons by eumelanin. Taken together, this study provides a reference for future forensic studies on determination of degradation of shed hair in a crime scene by following eumelanin radicals by utilizing the non-invasive, non-destructive, and highly specific EPR technique.
(© 2020 American Academy of Forensic Sciences.)
Databáze: MEDLINE
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