Soil has the potential to link items or individuals to a crime scene; however, the nature of traditional forensic soil analysis does not typically allow for its individualization. Rather than develop an entirely new methodology, it is more logical to adopt next-generation sequencing of the bacterial 16S ribosomal RNA gene, a well-established, scientifically validated technique in microbiology, for the forensic analysis of soil. Next-generation sequencing was employed to generate bacterial profiles from soils collected in ten diverse and nine similar habitats, across time and space within three habitats, and from various evidentiary items. Bacterial abundance charts, nonmetric multidimensional scaling, and a supervised classification technique were used to analyze profiles. Soils from diverse and similar habitats were largely differentiated from one another, with bacterial profiles separating in multidimensional space and/or being correctly assigned to their location of origin. Time and space within a habitat affected bacterial profile similarity; however, not enough to prevent the traceability of soils. Bacterial profiles from evidentiary items were correctly classified to their location of origin over a full year of storage, regardless of evidentiary type or storage temperature. These studies highlight the utility of next-generation sequencing and a combination of robust bacterial profile statistical methods for forensic soil analysis while also emphasizing the adoption of established techniques from other scientific disciplines to strengthen forensic science as a whole.
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