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Hyperspectral analysis of selected fabrics submerged in the Indian Ocean: An innovative way to aid in the estimation of the time human remains have spent in water

Beales, Elsie (2020) Hyperspectral analysis of selected fabrics submerged in the Indian Ocean: An innovative way to aid in the estimation of the time human remains have spent in water. Honours thesis, Murdoch University.

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Abstract

Estimating the time since death (minimum Post-Mortem Interval, minPMI) is crucial in forensic investigations. In an aquatic environment, this process is particularly challenging because of the complexity of a corpse’s decomposition process and the many factors related to the environment. Furthermore, there is a general paucity of research in this field. Recently, the use of the clothing discovered alongside a corpse has come under scrutiny: clothing has a high chance to be present, and their colonisation rate by aquatic organisms could be used to estimate the victim’s minimum Post-Mortem Submersion Interval (minPMSI). Besides a biological/zoological-based estimation, no other avenues to age clothing in an underwater context have been tested. This research is the first to focus on the use of Hyperspectral Imaging (HSI) to age fabrics, considering the modification of their optical properties as a result of exposure to a marine environment.

Cotton, neoprene, satin, and velvet were submerged underwater over a period of six months off the coast of Perth, Western Australia. In a pilot study, the fabrics were analysed using two different light scenarios (VIS-NIR and VIS-NIR + VIS-H) to identify which one would provide the best reflectance profiles. Results demonstrated that the additional halogen illumination (VIS-NIR + VIS-H) did not provide any extra information with respect to VIS-NIR. In the main study, the fabric’s spectral profiles were therefore captured using only VIS-NIR lighting. Profiles were generated for all submerged samples as well as controls (N=112), and the resulting data were compared within and between fabrics. The most significant differences were observed for the cotton and satin, with a strong negative regression observed between the months spent submerged and the profiles generated. These fabrics showed a significant change of the colour, texture, and structure, as marine organisms were highly attracted to them. Neoprene and velvet, instead, showed minimal significant changes, with the first few months showing similar profiles to the controls and differences toward the end of the experiment. As opposed to cotton and satin, neoprene and velvet were less affected by the marine organisms. Overall, in a forensic context, when investigated via HSI technology, thin and natural fabrics can provide the most information to the investigators.

This study is the first to provide data to support the estimation of minPMSI based on the use of remote sensing, HSI, on different fabric types placed in Western Australian marine waters, providing the potential for a new tool in estimation of the minPMSI for forensic investigation.

Item Type: Thesis (Honours)
Murdoch Affiliation: Medical, Molecular and Forensic Sciences
Supervisor(s): Magni, Paola and Pivrikas, Almantas
URI: http://researchrepository.murdoch.edu.au/id/eprint/57561
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