Groundwork of the rationalization of the study of forensic nucleic acid transfer

• Applicant: Professor Dr. Cornelius Courts
• Subject Area: Toxicology, Laboratory Medicine
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 520250530

Forensic DNA analysis is of immense importance in criminal investigations and in the legal assessment of crimes and offences and is currently an irreplaceable tool in forensic science casework and is considered the gold standard of forensic individualization. In the course of this steadily progressing method development, however, a shift in perspective in the forensic molecular biological interpretation of trace patterns has been observed for some years, so that contextualization, i.e. the classification of the DNA trace in its mode of generation, is becoming increasingly important. This is due to the fact that, due to a phenomenon known as "DNA transfer", DNA can be transferred between objects and/or persons by mere contact, i.e., it can be transferred and thus the DNA of a person can reach an object/person relevant to the crime even without the context of the crime. In court proceedings, therefore, the defense increasingly disputes not the origin of an incriminating DNA trace (this is even readily conceded on a regular base), but the context of its occurrence. It must then be decided whether another hypothesis formulated or constructed by the defense, which is not incriminating for the defendant, explaining the origin of the DNA trace containing his DNA is possible or even plausible. Despite already available computational models based on Bayesian networks, it is not possible on the basis of today's knowledge and available data to reliably calculate the probabilities of the occurrence of a crime scene trace assuming at least one hypothesis postulating DNA transfer events. The overarching goal of the planned project is therefore to lay several foundations for streamlining forensic nucleic acid transfer research and the applicability of its results. These are the establishment and commissioning of an internationally usable, open platform for the collection and availability of raw nucleic acid transfer data (1), the establishment of standard experiments for the characterization of non-transferential variability and the establishment of comparability between laboratories (2), the generation of first data sets for relevant transfer scenarios for input into and testing of the database (3) and first steps towards the systematization of RNA transfer research (4). After completion of the project, a sustainable and expandable basis for further research and for the systematic organization of the results from this research on forensic nucleic acid transfer and crime aspect reconstruction on activity level will exist, which would prepare the field for further development up to routine use and, moreover, open up far-reaching spaces for further research and teaching.

• DFG Programme: Research Grants