9:05 AM - 9:30 AM
[MGI31-01] Role and importance of geological and soil reference data in forensic geology reports of examination
★Invited Papers
Keywords:Forensic, geology, soil, geological maps, soil maps
Examination of geological material as trace evidence in a police investigation often consists of trace soil or sediment attached to an object of interest, such as a shoe, a vehicle or a shovel. The amount of material present is often small, often 100’s of mg, and may be fractionated due to preferential attachment or loss of different particle classes or mineral types. Because of these limitations, the best methods of examination of forensic geological materials are minimally destructive or focus on characterizing individual particles. The more common methods of examination are: optical microscopy for characterization of minerals, lithic fragments, palynomorphs, and other biological particles; color determination; X-ray diffraction; and SEM-EDS.
Two common goals of examination of forensic geological material are 1) COMPARISON: to compare the geological evidence to the soils and geological material at a crime scene to assess if the evidentiary soil could have originated from the crimes scene and 2) PROVENANCE: to examine and interpret the trace geological material for its possible geographic origin to aid the police investigation (e.g. searching for a clandestine burial based on soil on a shovel). The importance of published reference data for provenance examinations is evident to any geologist, but even for comparison examinations publications about the local and regional geology are quite important. The geologist-forensic examiner is presenting their result to a judge or a judge and jury who are unlikely to have sufficient geological knowledge to understand when a mineral assemblage is rare and when it is common, or when it is common in a geographically restricted region. The reference data, to include geological and soil maps, as well as theses, papers and reports, are important for geologist-forensic examiners to provide unbiased context for the importance of their results.
A few examples of how geological and soil reference data have been applied in forensic cases will be presented to include both examinations for soil comparison and soil provenance assessments.
Two common goals of examination of forensic geological material are 1) COMPARISON: to compare the geological evidence to the soils and geological material at a crime scene to assess if the evidentiary soil could have originated from the crimes scene and 2) PROVENANCE: to examine and interpret the trace geological material for its possible geographic origin to aid the police investigation (e.g. searching for a clandestine burial based on soil on a shovel). The importance of published reference data for provenance examinations is evident to any geologist, but even for comparison examinations publications about the local and regional geology are quite important. The geologist-forensic examiner is presenting their result to a judge or a judge and jury who are unlikely to have sufficient geological knowledge to understand when a mineral assemblage is rare and when it is common, or when it is common in a geographically restricted region. The reference data, to include geological and soil maps, as well as theses, papers and reports, are important for geologist-forensic examiners to provide unbiased context for the importance of their results.
A few examples of how geological and soil reference data have been applied in forensic cases will be presented to include both examinations for soil comparison and soil provenance assessments.