Forensic applications of the skin microbiome: a structured narrative review of donor association, contact inference, and crime-scene reconstruction.

BACKGROUND

Skin-associated microbial communities are individualized, anatomically structured, temporally dynamic, and readily transferred to contacted surfaces. These properties have generated interest in the skin microbiome as complementary forensic evidence when conventional human DNA or fingerprint evidence is limited.

METHODS

We conducted a structured narrative review guided by the Scale for the Assessment of Narrative Review Articles (SANRA). PubMed/MEDLINE was searched from database inception through 2 August 2026, and reference lists of eligible studies and recent reviews were examined. Peer-reviewed studies were evaluated for relevance to skin microbial individuality, temporal stability, touch transfer, donor or source inference, postmortem interval estimation, analytical standardization, and legal or ethical interpretation. Evidence was synthesized according to study realism, analytical resolution, validation design, and proximity to forensic casework.

RESULTS

The biological basis for forensic use is supported by reproducible inter-individual and body-site variation, including persistent strain- and gene-level features. Controlled studies show that skin-associated communities can be recovered from touched objects and clothing and can support donor differentiation, particularly when targeted markers, microbial single-nucleotide polymorphisms, or metagenomic features are used. Nevertheless, performance estimates are strongly affected by cohort size, body site, substrate, time since deposition, environmental background, contamination, and machine-learning design. Evidence for body-site and biological-trace source inference is promising, whereas postmortem interval estimation, chronological contact reconstruction, and spatial trajectory inference remain exploratory.

CONCLUSION

Skin microbiome profiling should currently be regarded as a source of investigative intelligence and potentially complementary evidence rather than a replacement for human DNA profiling. Translation into practice requires harmonized protocols, realistic multicenter validation, open and representative reference datasets, explicit error-rate reporting, likelihood-based interpretation, and proportionate ethical and legal safeguards.