Multiplex-RNA-analysis for detection and identification of forensically relevant organ tissues

In forensic investigations, identifying the bodily origin of components in biological trace material can be essential for the evidence-based reconstruction of criminal events. Complementing standard forensic DNA analyses, specific RNA markers can be utilized in the contextualization of biological traces, particularly to detect and identify forensically relevant body fluids and organ tissues. Here, we describe an optimized and expanded approach to mRNA-based organ tissue identification. This method involves targeted amplification of organ-specific mRNA equivalents and separation and visualization via capillary electrophoresis. 21 established markers for seven types of tissue were validated using a current extensive gene expression database and combined in a newly designed panel for capillary electrophoretic detection with six fluorescent dyes. The method was successfully tested on various post-mortem tissue samples, demonstrating the reliable identification of brain, heart, lung, liver, kidney, adipose tissue and skeletal muscle in forensic casework-relevant sample types. The robustness and sensitivity of this approach renders it a valuable tool for forensic investigations, enhancing the precision of tissue type identification in diverse scenarios. Moreover, the development and implementation of the method produced valuable insights into opportunities for the optimization of laboratory processes for other RNA-based procedures.