Analysis of 14C, 13C and Aspartic Acid Racemization in Teeth and Bones to Facilitate Identification of Unknown Human Remains: Outcomes of Practical Casework.

Rebecka Teglind,Irena Dawidson,Jonas Balkefors,Kanar Alkass

doi:10.3390/biom11111655

Abstract

The identification of unknown human remains represents an important task in forensic casework. If there are no clues as to the identity of the remains, then the age, sex, and origin are the most important factors to limit the search for a matching person. Here, we present the outcome of application of so-called bomb pulse radiocarbon (14C derived from above-ground nuclear bomb tests during 1955–1963) analysis to birthdate human remains. In nine identified cases, 14C analysis of tooth crowns provided an estimate of the true date of birth with an average absolute error of 1.2 ± 0.8 years. Analysis of 14C in tooth roots also showed a good precision with an average absolute error of 2.3 ± 2.5 years. Levels of 14C in bones can determine whether a subject has lived after 1955 or not, but more precise carbon turnover data for bones would be needed to calculate date of birth and date of death. Aspartic acid racemization analysis was performed on samples from four cases; in one of these, the year of birth could be predicted with good precision, whereas the other three cases are still unidentified. The stable isotope 13C was analyzed in tooth crowns to estimate provenance. Levels of 13C indicative of Scandinavian provenance were found in known Scandinavian subjects. Teeth from four Polish subjects all showed higher 13C levels than the average for Scandinavian subjects.

Highlights

Dead victim identification constitutes an important task for forensic professionals including forensic pathologists, anthropologists, and odontologists in their daily casework, in mass disasters
Bomb Pulse 14 C Dating of Tooth Crown Precisely Determines Date of Birth
Regarding tooth enamel and dentin, we found that bomb pulse 14 C analysis could predict the true year of birth with excellent precision even though several cases had been exposed to soil, air, and water for extended times, excluding any major degree of contamination of the teeth

Summary

Introduction

Dead victim identification constitutes an important task for forensic professionals including forensic pathologists, anthropologists, and odontologists in their daily casework, in mass disasters. If there are no clues as to the identity of the deceased, age, sex, and origin represent important information to limit the search for possible matching persons. Whereas the sex often can be determined by morphological characteristics, or by DNA analysis, the age of adult subjects is more difficult to estimate. Many different methods for estimating the age of a deceased person have been published, most of them based on examination of teeth and bones. Anthropological analyses based on morphological changes typically provide age estimation errors for adults of ±10 years [1,2,3,4,5,6], which imply intervals that are too wide to offer meaningful help in practical casework. All amino acids undergo conversion from L-form to D-form with time, and the extent of Biomolecules 2021, 11, 1655.

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