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Trace evidence dynamics: assessing the transfer and persistence of microbial diatom evidence in forensic investigation

22 March 2013

Kirstie Scott

Recognising and recovering minute quantities of evidentially significant material, can aid in forensic interpretation and provide scientific weight in criminal trial. The forensic use of diatoms has so far been focused upon diagnosing cases of drowning through identifying and attempting to exclude diatoms found in internal organs and the bone marrow with distinct localisations (e.g. Cameron, 2004; Ludes et al, 1999). Use of diatoms as trace evidence has been used to link people and objects with crimes involving freshwater and saltwater environments (e.g. Siver et al, 1993). Although diatoms naturally exist in abundance and can help to identify and compare/exclude localities, people, and objects; analysis of microbial evidence is so far underused in forensic contexts, with very little in the published literature. Diatoms are important environmental indicators due to their diversity and specificity to habitat location, and their resistance to chemical and temporal change. Diatoms primarily exist aquatically, however terrestrial and aerophilic diatoms are also dominant microscopic features of environments. The contribution of diatoms to forensic science has been researched within the realm of water; however there are significant gaps in current research as to the value of terrestrial diatoms in soils and other terrestrial surfaces, and their evidence dynamics in transferring and persisting over time.  This project aims to assess the degree of transferability of trace diatom particulates between a range of natural terrestrial habitats and their persistence on clothing over time. This study will consider the impact of variables including seasonality, moisture, and temporal decay; in order to gain further insights into the dynamics of trace microbial diatom evidence and their potential application to forensic enquiry.