Artificial chimerism and its impact on the forensic investigation of sexual offences

Genetic chimerism is crucial when assessing the effectiveness of medical treatments and surgical procedures. Factors that cause chimerism include genetic mutations, cell division processes, radiation exposure and cell fusion. Natural chimerism results from natural factors, while artificial chimerism results from medical procedures. It may produce deceptive DNA evidence, potentially causing erroneous accusations or exoneration of a guilty individual. This study aims to understand this phenomenon, measuring techniques and the standards followed in the interpretation of artificially induced chimerism following a systematic review of the literature related to chimerism and forensic evidencing techniques. This study comprehensively explores and consolidates existing studies on chimerism and its implications for sexual offences and investigates the influence of chimerism on forensic inquiries, particularly emphasising the treatments and procedures that may produce artificial chimerism. We reviewed multiple databases, encompassing peer-reviewed journals, grey literature and various online resources. DNA evidence plays a vital role in linking perpetrators to sexual assault cases but may produce misleading outcomes in instances involving a chimera. This concern is particularly significant where medical histories involve transplant or transfusion procedures. Though rare the potential impact on forensic investigation of sexual offences must be considered. © The Author(s) 2025