Comparative analysis of bones, mites, soil chemistry, nematodes and soil micro-eukaryotes from a suspected homicide to estimate the post-mortem interval

Abstract

Criminal investigations of suspected murder cases require estimating the post-mortem interval (PMI, or time after death) which is challenging for long PMIs. Here we present the case of human remains found in a Swiss forest. We have used a multidisciplinary approach involving the analysis of bones and soil samples collected beneath the remains of the head, upper and lower body and “control” samples taken a few meters away. We analysed soil chemical characteristics, mites and nematodes (by microscopy) and micro-eukaryotes (by Illumina high throughput sequencing). The PMI estimate on hair 14C-data via bomb peak radiocarbon dating gave a time range of 1 to 3 years before the discovery of the remains. Cluster analyses for soil chemical constituents, nematodes, mites and micro-eukaryotes revealed two clusters 1) head and upper body and 2) lower body and controls. From mite evidence, we conclude that the body was probably brought to the site after death. However, chemical analyses, nematode community analyses and the analyses of micro-eukaryotes indicate that decomposition took place at least partly on site. This study illustrates the usefulness of combining several lines of evidence for the study of homicide cases to better calibrate PMI inference tools.

An Experiment to Characterize the Decomposer Community Associated with Carcasses (Sus scrofa domesticus) on Oahu, Hawaii

“…These processes include gross postmortem changes (e.g., livor mortis, marbling, bloating), autolysis, putrefaction, insect larval development, scavenging activity, and many others. Taphonomy is relevant to medicolegal death investigation because proper interpretation of decomposition processes can accomplish investigative goals such as establishing the cause of death , locating clandestine graves , and estimating postmortem interval . An ecological approach to studying and applying taphonomy is often implemented because many decomposition processes are biologically mediated.…”

Soil Fungal Communities Investigated by Metabarcoding within Simulated Forensic Burial Contexts

“…Recently, several independent studies have demonstrated the applicability of this type of study to the estimation of PMI and have investigated the effects of different hosts (e.g. decomposing human [12][13][14][15][16], swine [17][18][19] or rodents [14,18,20]), different burial conditions (e.g. exposed on the surface [12][13][14][15][16][17][18]20] or shallow burials [15,19]), different environments (e.g.…”

“…decomposing human [12][13][14][15][16], swine [17][18][19] or rodents [14,18,20]), different burial conditions (e.g. exposed on the surface [12][13][14][15][16][17][18]20] or shallow burials [15,19]), different environments (e.g. indoor laboratory environments [14,20] or outdoor environments in different geographical locations [12][13][14][15][16][17][18][19]) and different sources (e.g.…”

Correlação entre a degradação da molécula de RNA proveniente da polpa dental e a estimativa de intervalo post mortem em condições simuladas de inumação

“…A definição de intervalo post mortem (IPM) diz respeito ao lapso temporal que transcorreu desde a ocorrência do óbito até o momento em que se tem início a análise do corpo ou suas partes disponíveis (SZELECZ, et al 2018). A estimativa do IPM tem seu prelúdio com o exame macroscópico do cadáver ou remanescentes ósseos, observando os aspectos que levam em consideração a aparência macroscópica, preservação do tecido e odor (WOESS, et al 2017).…”

“…O intervalo post mortem (IPM) é o período de tempo desde a ocorrência do óbito até o momento em que se passa a analisar o corpo e/ou seus remanescentes (SZELECZ, et al 2018). A estimativa deste intervalo é assunto de grande relevância no âmbito forense por seu papel importante na resolução de casos criminais.…”