Gravesoil derived postmortem interval using attenuated total reflectance-Fourier transform infrared spectroscopy and the influence of carrion-associated fabric.

Establishing time elapsed for unattended death scenes is crucial in formulating a timeline of events facilitating death investigations. However, traditional postmortem interval (PMI) methods rely on visually evaluating physical atrophy and are closely influenced by both biotic and abiotic variables associated with carrion. During the bloat stage, carrion produces a characteristic landscape known as the cadaver decomposition island (CDI), through the propagation of fluids rich in decomposition by-products. Here, attenuated total reflectance- Fourier transform infrared spectroscopy (ATR-FT-IR) was employed as a non-invasive, low input, low preparation interface for determining PMI from simulated Mus musculus burial gravesoil. Furthermore, understanding the influences of environmental and inter-individual differences in gaining accurate PMI is important to validate, prior to implementation to enhance the current forensic toolkit. It is documented that the presence, type and weight of clothing interferes with progression through decomposition. The subsequent impacts of clothing material (cotton, polyester, viscose) on CDI footprint development will be reflected in the biological and chemical characteristics of this ecosystem. Principal component analysis (PCA) of the IR spectra showed two clusters of samples corresponding to control and gravesoil. PC loadings plot showed that the 3100 - 1000 cm-1 spectral range attributed for over 95% of the variance. Bands within this range are ascribed to the presence of lipids, proteins and volatile organic compounds (VOCs) as byproducts of mammalian decomposition. Overall, presence and fabric type impacted decomposition, spectral CDI detection and grave discrimination. This study questions the efficacy of proxy size and microcosm design in conducting applicable forensic research in lieu of taphonomy facilities or ethical constraints.