Monitoring the extent of vertical and lateral movement of human decomposition products through sediment using cholesterol as a biomarker

Abstract

Due to the lack of human decomposition research facilities available in different geographical regions, the extent of movement of human decomposition products from a cadaver into various sedimentary environments, in different climates, has not been able to be studied in detail. In our study, a human cadaver was placed on the surface of a designated plot at the Australian Facility for Taphonomic Experimental Research (AFTER), the only human decomposition facility in Australia, where the natural process of decomposition was allowed to progress over 14days in the Australian summer. Sediment columns (approximately 1m deep) were collected at lateral distances of 0.25m, 0.5m, 1.0m and 2.5m in each of four directions from the centre of the torso. Plot elevation and weather data were also collected. Each sediment column was subdivided, dried and homogenised. A sample was isolated from each sediment subdivision, extracted with hexane, and the hexane extract cleaned with citrate buffer (pH 3), filtered and spiked with cholesterol-D internal standard. After derivatisation with BSTFA+1% TMCS, cholesterol was monitored in the samples using targeted gas chromatography tandem mass spectrometry analysis. A positive result for decomposition products was given if the cholesterol abundance in the test sample was higher than that detected in the 'control' samples of a similar substrate type collected prior to cadaver placement. Within the confines of the experimental design and the measured parameters, lateral leaching was observed over distances of up to 2.5m from the centre of the torso, which was the maximum distance tested in the study. Vertical leaching was detected to depths of up to 49cm below the ground surface. Such data can aid the development of policies related to plot sizing and sediment renewal and regeneration at other human decomposition facilities and at cemeteries. The density and distribution of cholesterol surrounding the cadaver in this study can also help forensic investigators interpret cases involving remains that have been moved or scavenged.

Estimating postmortem interval for human cadavers in a sub‐tropical climate using UV‐Vis‐near‐infrared Spectroscopy

“…In situations of the discovery of scattered bones, identification of the CDI is key to determining PMI. The spread of CDI can be quite large [30], especially for organic C and N compounds [8], and generally a quick field indication is an increase in soil electrical conductivity where it can be an order of magnitude higher relative to surrounding control soils [17][18]. Body burn (blackening) on the soil surface is also a good indicator of the location of a CDI, which can persist for over one year at some sites or lush vegetation patches which are observable after 18 months.…”

“…At facilities with little slope such as FACTS, expectations are that decomposition products may migrate vertically down the soil profile suggesting the need for deeper samples. Luong et al[30] observed decom-…”

Why does the UK need a Human Taphonomy Facility?

“…The scope of this research necessarily includes many sciences related to forensic science, such as geology and geophysics, archaeology, environmental science, ecology, botany, pathology and medicine, and analytical chemistry, for example. Current research at AFTER is monitoring how facial tissue thicknesses change with post-mortem interval (Stuzner, 2016), as well as volatile organic compound release from cadavers (Luong et al, 2018;Knobel et al, 2018). In addition, research has also started on the detection of clandestine and mass graves through the use of LiDAR scanning, hyperspectral imagery, infra-red photography and drone imaging (Blau, 2017).…”

Estudio de Necrosoles y suelos de cementerio

“…Además la localización e identificación de entierros o sitios que fueron depositarios de inhumaciones, en la actualidad se pueden caracterizar y detectar por medio de la elaboración de un perfil de lixiviación, respecto a la distribución horizontal y vertical del colesterol, en el sustrato circundante al cuerpo enterrado, mediante su persistencia en el ambiente, dado su carácter de biomarcador [53].…”