Impact of fabric type, exhumation and translocation of carrion on successive grave soil ecology and chemistry aiding in PMI estimation

Watson, P ORCID: 0000-0002-1457-1520 (2026) Impact of fabric type, exhumation and translocation of carrion on successive grave soil ecology and chemistry aiding in PMI estimation. Doctoral thesis, Liverpool John Moores University.

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Abstract

Mammalian carrion are substantial nutrient resources in terrestrial environments, inducing a rapid successional response in the surrounding soils physicochemical and ecological properties. This distinct localised environment is known as the cadaver decomposition island (CDI) with grave soil analysis proven a successful means of discriminating post-mortem (PMI) and post-burial interval (PBI). However, mammalian decomposition is highly governed by both biotic and abiotic factors associated with the cadaver and its deposition locale. Despite significant research efforts, paucity of confounding variables remains pertinent to address prior to the formulation of forensic ecogenomic and physicochemical models that can complement and enhance the current forensic toolkit.
To monitor post-mortem microbial and physicochemical profiles in grave soil, 59 ex situ decomposition microcosms containing Mus musculus were maintained for 170 days. Three separate studies were conducted designed to investigate the influence of carrion-associated fabric wrapping, full body exhumation and reburial of translocated remains on edaphic temporal necro-ecology and necro-physicochemistry. Moreover, the 16S rRNA bacterial consortia was analysed using restriction fragment length polymorphism (RFLP) and high throughput next generation sequencing (NGS), quantified and compared with Hill ecological indices for taxa richness (0D), diversity (1D and 2D) and community evenness. Chemical changes were measured using attenuated total reflectance – Fourier transform infrared (ATR-FTIR) and handheld near infrared (NIR) spectroscopy as low input, low preparation, rapid and established forensic interfaces. Murine models were chosen as human proxies in this work as they were the most appropriate analogue for scale, replicability, and space in laboratory facilities. Additionally, current legal and ethical guidelines restrict access to taphonomy centres for work undertaken in the United Kingdom.
Overall, IR spectroscopy was successful in discriminating the presence of decomposing murine remains from soils primarily highlighting divergences in lipid and protein profiles. However, samples taken from all three studies inherently contained the same endogenous constituents, causing higher incidences of type I and II chemometric errors that interfered with the delineating between parameters of the experimental microcosms. 16S rRNA gene taxonomic resolution highlighted key bacterial indicators of post-burial, post-exhumation and post-reburial soils down to genera and species markers associated with these extenuating forensic scenarios. This research programme in novel in bringing together spectroscopic and forensic ecogenomic techniques to assess soil microbial and physiochemical successional trends in response to fabric type, time of exhumation and remains translocation, routinely encountered in forensic casework. The findings validate current understanding to the terrestrial necrobiome while providing definitive proof-of-concept to underscore the importance of further research, particularly on exhumation and subsequent reburial, on larger taphonomic proxies in situ.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Necrobiome; Microbial Ecology; PMI; PBI; Spectroscopy
Subjects:	Q Science > QD Chemistry Q Science > QR Microbiology
Divisions:	Pharmacy and Biomolecular Sciences
Date of acceptance:	1 June 2026
Date of first compliant Open Access:	26 May 2026
Date Deposited:	26 May 2026 14:53
Last Modified:	26 May 2026 14:53
DOI or ID number:	10.24377/LJMU.t.00028595
Supervisors:	Ralebitso Senior, K and Assi, S
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28595

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