A new scientific review has examined how microorganisms living in soil could strengthen forensic investigations by providing additional information about where trace evidence originated.
Published on November 11, 2026, in the Egyptian Journal of Forensic Sciences, the research assessed 75 studies investigating the physical, chemical, biological and microbial properties of soil.
The review was conducted by Drashti Bhuptani Sagav and Ajay Kumar of Galgotias University in India.
Soil is frequently encountered during criminal investigations. Small quantities can become attached to footwear, clothing, vehicles, tools and other objects, potentially providing information about contact with particular environments.
Traditional forensic soil examinations consider characteristics such as colour, texture, mineral composition and chemical properties.
However, researchers are increasingly investigating whether the microorganisms present in soil can provide another useful layer of information.
Different environments support different microbial communities, influenced by factors including geography, climate, vegetation, land use and soil chemistry.
These differences can sometimes produce microbial patterns that help distinguish samples collected from different locations.
The review examined research involving DNA sequencing methods, including bacterial 16S ribosomal RNA analysis, fungal marker analysis and shotgun metagenomics.
Such techniques allow scientists to characterize microbial communities without relying solely on organisms that can be cultured in a laboratory.
Researchers also evaluated studies using machine-learning approaches to classify soil samples and estimate their possible geographic origins.
According to the review, combining microbial information with conventional physical and chemical measurements could improve the discrimination of soil samples in some investigative settings.
Potential applications include comparing material recovered from a suspect's footwear with samples from a crime scene, examining environmental transfers and supporting investigations involving human remains.
The researchers also considered how microbial changes associated with decomposition might contribute to estimating the postmortem interval.
However, the review identified important limitations that currently restrict the routine forensic use of soil microbiome analysis.
Microbial communities change with temperature, moisture, seasonal conditions and environmental disturbance.
Two samples collected from the same location at different times may therefore exhibit differences, while samples from separate environments can share certain microbial characteristics.
The absence of comprehensive, geographically referenced microbial databases presents another obstacle.
Without sufficiently representative reference collections, investigators may struggle to interpret how strongly a microbial pattern supports a proposed geographic association.
Laboratory contamination, sampling procedures, bioinformatics methods and the lack of standardized analytical protocols can also affect reliability.
The authors emphasized that additional validation, reproducible analytical methods and appropriate interpretation frameworks are necessary before microbial soil evidence can be used routinely in judicial proceedings.
Importantly, microbial similarity does not establish that a suspect visited a particular location or participated in a crime.
Such findings must be evaluated alongside other evidence and alternative explanations for environmental transfer.
As a systematic review, the publication synthesizes existing research rather than reporting a newly validated forensic identification technique.
Its findings nevertheless demonstrate why soil microbiology is receiving growing attention as a potential complement to established trace-evidence examinations.