Ta1_06

MODELLING CORRECTIONS OF BOMB-PULSE RADIOCARBON DATING IN FORENSIC CASES

Sveinbjörnsdóttir A¹, Olsen J², Heinemeier J²

¹Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland, ²Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark

Identification of human remains by radiocarbon dating and stable isotope approach can be of extreme importance in forensic cases. However, radiocarbon dating has to rely on modelled corrections due to radiocarbon changes in the atmosphere, collagen turnover rate and marine reservoir effect that are often difficult to estimate and verify.  In this presentation, we will ascertain how close the modelled corrections are to reality by comparing radiocarbon ages of human individuals with the known actual time of death (and birth).

     Two bone samples from unidentified individuals were radiocarbon dated by request of the Icelandic police, to determine whether the human remains were recent and of forensic relevance. In both cases the bones were well preserved and the extracted collagen of good quality. The dates were performed in 2017 and 2019 respectively, and both individuals turned out to be modern, falling within the bomb-pulse period. Isotope data showed no or limited indication of marine diet. To provide a quick forensic result, we took the naïve approach of a standard ten-year correction for bone collagen turnover and no marine correction.

      After our report, the police applied DNA  testing and managed to identify both individuals. Accordingly, we now know their time of birth as well as their death dates. In both cases, we had estimated their time of death too early by 10 and 20 years respectively. We have initiated attempts of better modelling of bone turnover and marine reservoir corrections in connection with bomb-pulse dating.