Isotope ratio mass spectrometry in forensic science applications

Identification and analysis of man-made geological product particles to aid forensic investigation of provenance in the built environment

This is the author accepted manuscript. The final version is available from Geological Society of London via the DOI in this record

/pdf/automated-mineralogical-profiling-of-soils-as-an-indicator-2b8xfey1fz.pdf

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

Compositional data from a soil survey over North Canberra, Australian Capital Territory, are used to develop and test an empirical soil provenancing method. Mineralogical data from Fourier transform infrared spectroscopy (FTIR) and magnetic susceptibility (MS), and geochemical data from X-ray fluorescence (XRF; for total major oxides) and inductively coupled plasma-mass spectrometry (ICP-MS; for both total and aqua regia-soluble trace elements) are performed on the survey's 268 topsoil samples (0-5 cm depth; 1 sample per km2 ). Principal components (PCs) are calculated after imputation of censored data and centered log-ratio transformation. The sequential provenancing approach is underpinned by (i) the preparation of interpolated raster grids of the soil properties (including PCs); (ii) the explicit quantification and propagation of uncertainty; (iii) the intersection of the soil property rasters with the values of the evidentiary sample (± uncertainty); and (iv) the computation of cumulative provenance rasters ("heat maps") for the various analytical techniques. The sequential provenancing method is tested on the North Canberra soil survey with three "blind" samples representing simulated evidentiary samples. Performance metrics of precision and accuracy indicate that the FTIR and MS (mineralogy), as well as XRF and total ICP-MS (geochemistry) analytical methods, offer the most precise and accurate provenance predictions. Inclusion of PCs in provenancing adds marginally to the performance. Maximizing the number of analytes/analytical techniques is advantageous in soil provenancing. Despite acknowledged limitations and gaps, it is concluded that the empirical soil provenancing approach can play an important role in forensic and intelligence applications.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/1556-4029.14727

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

Identifying soil provenance based on portable X-ray fluorescence measurements using similarity and inverse-mapping approaches – A case in the Lower Hunter Valley, Australia

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.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1556-4029.14060

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

Background survey of polyethylene in the Australian Capital Territory - A demonstration of variability in isotopic abundance values and their application to forensic casework.

Timothy Simpson

Papers

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

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

Background survey of polyethylene in the Australian Capital Territory - A demonstration of variability in isotopic abundance values and their application to forensic casework.