Application of Particle-Correlated Raman Spectroscopy for the Forensic Examination of Soils

Particle-Correlated Raman Spectroscopy (PCRS) is a novel yet reliable analytical technique that has the potential to add significant value to the forensic examination of soil evidence. PCRS is capable of delivering particle size distribution and microscopic morphological characteristics for the particles present within a soil, and at the same time allows secure mineral identification. The overall aim of this proposed research is to investigate the application of PCRS for the automated and objective analysis and comparison of soil samples, which will address the major criticisms of modern forensic soil analysis as being too time-consuming, labor-intensive and subjective. The proposed research is split into four parts which are designed to enable a comprehensive understanding of the value of PCRS for forensic soil analysis. Part 1 will investigate the optimization of sample preparation, data collection parameters and data analysis techniques in order to maximize the information obtained from PCRS analysis of soils. Part 2 will use PCRS to examine the lateral and depth variation of soils within specific locations representing different types of soil. Part 3 will focus on evaluating the analysis of soil samples collected from mock evidence (shoes, shovels and clothing). Accumulations of soil on footwear and digging instruments (e.g., shovels) are the traditional items of evidence analyzed for comparison with a reference sample or for provenance determination. Soil evidence can also be collected from clothing items. These will be the focus for this part of the research, where the soil collected from these mock evidence items will be compared to the collected exemplar soils. Part 4 will focus on the analysis of a large sample set of different soils in order to determine the differentiation ability of PCRS and to evaluate the match characteristics (and chemometric methods) identified in Part 1. PCRS has the potential to provide an automated analytical method for soil analysis that provides more information about a sample than is currently available through traditional examinations via its sophisticated imaging and Raman capabilities. Objective and scientifically sound evidence interpretation will be accomplished by data analysis with multivariate chemometric methods. Ultimately, this research will determine how PCRS can be used to maximize discrimination and comparative information from soil samples, which has the capability of promoting an increased awareness of the unrealized potential of this valuable type of physical evidence. Note: This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14).