Premium
Forensic determination of hair deposition time in crime scenes using electron paramagnetic resonance
Author(s) -
Shankar Nikhita,
Guimarães André O.,
Napoli Eleonora,
Giulivi Cecilia
Publication year - 2021
Publication title -
journal of forensic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 96
eISSN - 1556-4029
pISSN - 0022-1198
DOI - 10.1111/1556-4029.14570
Subject(s) - electron paramagnetic resonance , radical , melanin , unpaired electron , electron paramagnetic resonance spectroscopy , chemistry , photochemistry , nuclear magnetic resonance , biochemistry , physics
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.