Evaluation of the Spatial Variability of Soils: Application to Forensic Science.

In Forensic Science, there are two main types of questions which are asked when soil samples are involved.  The first is comparative, which involves trying to connect a suspect to the crime scene using soil found on the suspect’s belongings.  The second is investigative, and involves trying to identify the location from which a sample originated.  Current analysis of soil samples in Forensic Science mostly involves microscopy, and sometimes x-ray diffraction.  However, there is little to no statistical data available on how well soil samples can be distinguished.  The primary goal of this research is to use a suite of soil analysis techniques to determine if soil samples can be linked to specific map units.  In addition, this study aims to provide some of the missing statistical data, which could influence the relevance of soil data, and provide information regarding the reliability of soil sample analysis for Forensic Science.  Soil samples (0-10 cm) were taken from Fallbrook sandy loam map units (5 locations) and adjacent map units (3 locations) in Riverside and San Diego County.  Samples are currently being analyzed via various physical, mineralogical and chemical techniques including particle size analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and sequential chemical extractions.  Preliminary results from physical analyses have thus far supported previous assertions of the necessity of relying on more than one analysis in order to make a reliable comparison between samples, no matter the sample origin.