Predictive Soil Provenancing (PSP): An Innovative Forensic Soil Provenance Analysis Tool

Abstract

Soil is a common evidence type used in forensic and intelligence operations. Where soil composition databases are lacking or inadequate, we propose to use publicly available soil attribute rasters to reduce forensic search areas. Soil attribute rasters, which have recently become widely available at high spatial resolutions, typically three arc‐seconds (~90 m), are predictive models of the distribution of soil properties (with confidence limits) derived from data mining the inter‐relationships between these properties and several environmental covariates. Each soil attribute raster is searched for pixels that satisfy the compositional conditions of the evidentiary soil sample (target value ± confidence limits). We show through an example that the search area for an evidentiary soil sample can be reduced to <10% of the original investigation area. This Predictive Soil Provenancing (PSP) approach is a transparent, reproducible, and objective method of efficiently and effectively reducing the likely provenance area of forensic soil samples.

Forensic soil provenancing in an urban/suburban setting: A sequential multivariate approach

“…Rawlins et al [9] characterized the prediction of the provenance of a sample of earth-related material as "one of the most difficult and challenging tasks for analytical earth scientists." Caritat et al [11] introduced a predictive soil provenancing method that does not require a specific soil survey to be carried out over an area of interest. More typically, however, forensic soil provenancing is implemented empirically by comparing the spatial multivariate information contained in the evidentiary soil's geochemistry, mineralogy, bulk properties, etc., to either purposely acquired or pre-existing knowledge (see fig.…”

“…More typically, however, forensic soil provenancing is implemented empirically by comparing the spatial multivariate information contained in the evidentiary soil's geochemistry, mineralogy, bulk properties, etc., to either purposely acquired or pre‐existing knowledge (see fig. 1 in [ 11 ]). Such knowledge generally is derived from soil geochemical surveys and stored in databases containing this same or similar multivariate information over the region of interest at an appropriate density [ 12 ].…”

Automated mineralogical profiling of soils as an indicator of local bedrock lithology: a tool for predictive forensic geolocation

“…This use of soil trace evidence to determine the geographic position of otherwise unknown locations can be referred to as predictive geolocation (Pirrie et al, 2017) and is of increasing interest to the forensic geoscience community (e.g. Stern et al, 2019;Caritat et al, 2019).…”