Introduction: Microbiological examinations are one of the vital basic methods for diagnosing the etiology of infections. They cannot only be used for clinical purposes but also hold significant potential in forensic pathology. Microbiology is expected to provide insights into the origin of bio crimes, cause of death, time since death, and provides evidence in crimes such as sexual assaults, and homicide. Vaginal and skin microbiota play crucial roles in maintaining host defense, yet their unique microbial fingerprints have also become highly relevant in forensic investigations, particularly in the detection of sexual assault and interpersonal violence. Microbiome forensics may offer a groundbreaking method to track sexual assault suspects through unique bacterial signatures left during intercourse. While conventional forensic techniques rely heavily on DNA, toxicology, and physical examination, microbial signatures can provide an additional layer of evidence when traditional methods fail or are inconclusive. This new identification method could therefore assist a large number of victims, especially in cases where DNA evidence is absent or degraded.
Methods: This review article was conducted by analyzing published data from international databases including PubMed, Scopus, and Web of Science between 2000 and 2025. Keywords such as vaginal flora, skin microbiota, forensic microbiology, sexual assault, and microbial signature were used. Studies focusing on the composition of normal vaginal flora, normal skin flora, genital microbial sexually transmitted infections and their alterations in the context of sexual assault were selected. Comparative evaluation of sequencing-based approaches and conventional microbiological culture methods was performed to highlight their forensic relevance.
Results: Findings indicated that Lactobacillus spp. dominate the normal vaginal flora, maintaining acidic pH and protecting against pathogenic colonization. In cases of sexual assault, disruption of this balance may occur, often marked by the introduction of exogenous microorganisms such as Gardnerella vaginalis or non-native skin bacteria. Microbial alterations following sexual assault are not only detectable but may persist for a certain period of time, allowing for forensic monitoring. Moreover, psychological stress and trauma induced by the assault have also been shown to affect the vaginal microbiome. Studies conducted on assaulted women and children demonstrated that both the vaginal microbial community and host immune responses including changes in antigens and cytokines during sexual arousal differ significantly from those observed in individuals without a history of sexual assault or rape. Similarly, the skin microbiota composed mainly of Staphylococcus epidermidis, Corynebacterium spp., and Cutibacterium (Propionibacterium) acnes shows considerable variation across individuals and body sites. The uniqueness of the skin microbiome represents a crucial forensic marker in resolving assault cases. During physical assault, microbial traces from the assailant can be transferred to the victim, and vice versa. In some cases, either the perpetrator or the victim may carry a distinctive skin or genital microbial infection, which, when combined with appropriate sampling methods and advanced diagnostic tests, allows for microbial profiling. By matching the microbiomes of suspects and victims, forensic experts can achieve a more accurate reconstruction of events and improved identification of the assailant. Transfer of microbial communities between victim and assailant has been documented, with microbial signatures serving as trace evidence linking physical contact. Metagenomics sequencing studies demonstrated that microbial profiles can be as individual-specific as human DNA, offering potential use as a supplementary forensic tool. However, external factors such as hygiene practices, antibiotic usage, and environmental contamination remain significant challenges.
Conclusion: The evaluation of vaginal and skin microbiota offers promising applications in forensic medicine, especially in the investigation of sexual assault. While microbial profiling is not yet standardized for courtroom application, it represents a powerful complementary tool to conventional forensic methods. Future perspectives include the establishment of microbial reference databases, the integration of next-generation sequencing with artificial intelligence for microbial signature analysis, and the development of international guidelines for forensic microbiology. Further research is required to overcome technical, environmental, and legal limitations, but the use of vaginal and skin flora as forensic evidence has the potential to revolutionize the investigation of sexual crimes.