A systematic review of soil in forensic investigations: from physicochemical characterization to microbial fingerprinting

Background Soil is a versatile, and one of the most widely encountered trace materials during forensic investigations. Soil pertains unique physicochemical characteristics, having varied biological composition that it’s specified to geological locations. These specific characteristics confer linkage to suspects, victims, and related articles at the scene of incident. Despite its long history of forensic application, the full analytical potential of soil, particularly through the lens of modern molecular microbiology, has yet to be fully consolidated in a single comprehensive review. Main Body This review examines soil as forensic trace evidence across its physical, chemical, biological, and microbiological dimensions, with particular emphasis on the emerging role of the soil microbiome as a forensic discriminator. A systematic search for peer-reviewed literature published between 2002 and 2025 have been conducted using the databases sources: Search Terminologies used in this search included following combination of words: “forensic soil”, “soil trace evidence”, “soil microbiome forensics”, “soil microbial fingerprint”, “next-generation sequencing forensics”, “post-mortem interval soil”, and “geolocation microbial”. A total of 75 studies were included after screening for relevance, methodological quality, and date of publication. Key applications include geographic origin determination, suspect–scene linkage, post-mortem interval estimation, and corroboration of conventional forensic evidence. Critical challenges include the absence of standardized protocols, limited geo-referenced, reference databases, environmental variability of microbial communities, and unresolved questions of legal admissibility. Conclusion An integrated, multidisciplinary framework combining physical, chemical, and microbiological analyses, supported by validated bioinformatics pipelines and comprehensive reference databases, is necessary to realize the full forensic potential of soil. Addressing current methodological and legal gaps will be essential for the routine admission of soil microbiome evidence in judicial proceedings.