Evaluative sub-source and activity level reporting in Austria, Germany and Switzerland

An increasing number of scientific studies in the field of forensic genetics suggest that questions arising in courtrooms have shifted in recent years from "Whose DNA is it?" to "How did that person's DNA get there?", or, expressed in the terminology of the field, from questions at the sub-source level to questions at the activity level. The increasing number of studies on TPPR (transfer, persistence, prevalence, recovery) of DNA are of great help to answer such questions at the activity level. However, to date, little information is available about the actual numbers of cases in which activity level assessments were of relevance for the court. It must be considered an open question whether this increasing interest in activity level reporting (ALR) in the scientific community is based on an actual increase of requests for reporting in casework, or whether it is currently rather driven by a greater awareness for the complexity of DNA reporting in the academic arena itself. To assess this question for a part of Central Europe, we conducted an online survey in fourteen institutes in the German-speaking region of Switzerland, in Austria and in Germany over three months in spring 2024. Although the participants believe that ALR is useful for the evaluation of DNA evidence, they also report having limited knowledge therein and that it is in fact rarely requested in practice. No significant increase in ALR reporting was noted by the participants we surveyed over the last ten years. In addition to the development of ALR reporting, we also assessed evaluative sub-source level reporting (ESSLR) to monitor the potential effect of the advent of probabilistic genotyping on numbers of likelihood ratio (LR) calculations. It appears that most participating institutions still use binary/semi-continuous calculation software rather than fully continuous models. There has been no significant increase or decrease in LR calculations for single/major profiles, nor for DNA mixtures. The absence of ALR requests together with a constant number of ESSLR calculations thereby strongly suggests that the perceived shift from (sub-)sub-source level reporting to activity level reporting did not (yet) happen in German-speaking countries.