Cadaver Decomposition Research Articles

Water volume influences antibiotic resistomes and microbiomes during fish corpse decomposition

Corpse decomposition may cause serious pollution (e.g., releasing antibiotic resistance genes) to the water environment, thereby threatening public health. However, whether antibiotic resistance genes (ARGs) and microbiomes are affected by different water volumes during carcass decomposition remains unknown. Here, we investigated the effects of large/small water volumes on microbial communities and ARGs during fish cadaver decomposition by 16S rRNA high-throughput sequencing and high-throughput quantitative PCR. The results showed that the large water volume almost eliminated the effects of corpse decomposition on pH, total organic carbon (TOC), and total nitrogen (TN). When the water volume enlarged by 62.5 fold, the relative abundances of some ARGs resisting tetracycline and sulfonamide during carcass decomposition decreased by 217 fold on average, while there was also a mean 5267 fold increase of vancomycin resistance genes. Compared with the control group, the enriched types of ARGs varied between the large and small volume. Water volume, mobile genetic elements, and carcass decomposition were the most important factors affecting ARG profiles. Many opportunistic pathogens (like Bacteroides and Comamonas) were enriched in the corpse group. Bacteroides and Comamonas may be potential hosts of ARGs, indicating the potential for the spread of ARGs to humans by water pathogenic bacteria. This research highlights that the "dilution effect" can contribute to eliminating this adverse effect during corpse decomposition to a certain extent. It may provide references for environmental governance and public health.

The Dynamic of Insect Population Succession in Bird Poisoned by Pyrethroid Insecticides

Insecticide poisoning is one of the causes of death in wild birds. One of the insecticides that are often used is a pyrethroid. This study aims to determine the succession of insects in birds intoxicated by pyrethroid pesticide. This research was conducted in Dramaga campus, IPB University, Bogor, Indonesia. One quail (Coturnix coturnix japonica) was used as a control which was killed by manual neck dislocation, and one bird was treated orally treated with acute dose pyrethroid pesticide. Cadavers are placed in insect traps until they reach the skeletal stage of decomposition. Insects that enter the trap are collected every 6 hours for 24 hours, from the first day until the whole process of decomposition of the carrion reaches the skeletal stage. Then the insects are identified and counted. The results showed that the cadaver decomposition process in the treatment group took longer than the control group. In the control group, insects arrived for approximately 138 hours after the cadaver was placed, while the treatment group took approximately 324 hours. The types of insects in these two groups are relatively the same, namely flies (Order Diptera: Calliphoridae, Muscidae), cockroaches (Order Dictyoptera: Blattidae and Blaberidae) and Sarcophagidae), beetles (Order Coleoptera: Scarabidae), ants (Order Hymenoptera: Formicidae), earwigs (Order Dermaptera: Anisolabididae). Chrysomya megachepala was the dominant insect over the others and was always present from the early stages to post-decay in control and pyrethroid treatment.

Carcasses at Fixed Locations Host a Higher Diversity of Necrophilous Beetles.

Simple SummaryWhereas vertebrate scavengers have a higher diversity reported at randomly placed carcasses, the drivers of insect diversity on carrion, such as the exposure type (fixed versus random) or the carrion species, are still incompletely understood. We analyzed beetle diversity at differently exposed carcasses in the low-range mountain forest of the Bavarian Forest National Park in Germany. We tested if scavenging beetles, similarly to vertebrate scavengers, show a higher diversity at randomly placed carcasses compared to easily manageable fixed places. Ninety-two beetle species at 29 exposed wildlife carcasses (roe, red deer, and red foxes) were detected. Beetle diversity was higher at fixed locations possessing extended highly nutrient-rich cadaver decomposition islands as important refuges for threatened red-listed species, such as Necrobia violacea (Coleoptera: Cleridae). Particularly noticeable in our insect traps were the following two rare species, the “primitive” carrion beetle Necrophilus subterraneus (Coleoptera: Agyrtidae) and the false clown beetle Sphaerites glabratus (Coleoptera: Sphaeritidae). In Europe, only the species S. glabratus out of the genus Sphaerites is present. This emphasizes the importance of carrion for biodiversity conservation. We clearly show the relevance of leaving and additional providing wildlife carcasses in a dedicated place in protected forests for preserving very rare and threatened beetle species as essential members of the decomposing community.In contrast to other necromass, such as leaves, deadwood, or dung, the drivers of insect biodiversity on carcasses are still incompletely understood. For vertebrate scavengers, a richer community was shown for randomly placed carcasses, due to lower competition. Here we tested if scavenging beetles similarly show a higher diversity at randomly placed carcasses compared to easily manageable fixed places. We sampled 12,879 individuals and 92 species of scavenging beetles attracted to 17 randomly and 12 at fixed places exposed and decomposing carcasses of red deer, roe deer, and red foxes compared to control sites in a low range mountain forest. We used rarefaction-extrapolation curves along the Hill-series to weight diversity from rare to dominant species and indicator species analysis to identify differences between placement types, the decay stage, and carrion species. Beetle diversity decreased from fixed to random locations, becoming increasingly pronounced with weighting of dominant species. In addition, we found only two indicator species for exposure location type, both representative of fixed placement locations and both red listed species, namely Omosita depressa and Necrobia violacea. Furthermore, we identified three indicator species of Staphylinidae (Philonthus marginatus and Oxytelus laqueatus) and Scarabaeidae (Melinopterus prodromus) for larger carrion and one geotrupid species Anoplotrupes stercorosus for advanced decomposition stages. Our study shows that necrophilous insect diversity patterns on carcasses over decomposition follow different mechanisms than those of vertebrate scavengers with permanently established carrion islands as important habitats for a diverse and threatened insect fauna.

Predicting the postmortem interval of burial cadavers based on microbial community succession

Previous studies have demonstrated that microbial community succession during the decomposition of cadavers could be used to estimate the postmortem interval (PMI). However, the vast majority of the existing studies focused on exposed cadavers. In fact, burial cadavers are common scenarios for forensic investigations. In this study, the microbial communities from gravesoil, rectum and skin of burial SD rat cadavers during decomposition were characterized using 16S rRNA gene high-throughput sequencing. We predicted PMI based on the microbial community succession. Obvious differences in microbial community structures were observed between different stages of decomposition. Later decay stages had a lower alpha diversity compared to earlier decay stages. Significant linear relationships between similarities of the microbial communities and postmortem intervals were observed, manifesting regular succession over the course of decomposition. Furthermore, we combined random forest models with postmortem microbial features to predict PMI. The model explained 86.83%, 84.55% and 81.67% of the variation in the microbial community, with a mean absolute error of 1.82, 2.06 and 2.13 days within 60 days of decomposition for gravesoil, rectum and skin of burial cadavers, respectively. Overall, our results suggested that postmortem microbial community data could serve as a potential forensic tool to estimate accurate PMI of burial cadavers.

Soil chemistry dynamics of Sus scrofa carcasses with and without delayed Diptera colonization.

Under normal circumstances, insects such as blow flies will oviposit and larvae will colonize a carcass as soon as possible. However, insect colonization on a carcass may be delayed due to the effects of wrapping, shallow burial, addition of lime derivatives to mitigate scavenging and odor, or extreme weather. The impacts of delayed insect colonization on carcass decomposition and its subsequent effect on soil chemistry profiles have not been examined to date. The objectives of this study were to determine soil chemistry dynamics associated with porcine carcasses experiencing delayed insect colonization for 7-day or 14-day. Soil chemistry profiles such as ammonium-N (NH4 -N), orthophosphate-P (PO4 -P), and dissolved organic carbon (DOC) were significantly different among treatments: insect inclusion (immediate access of blow fly colonization on porcine carcasses), 7-day insect exclusion and 14-day insect exclusion (blow fly access was delayed up to 7-day and 14-day). Furthermore, significant differences of soil chemical profiles were detected between days of decomposition and soil regions. Soil moisture, NH4 -N, PO4 -P, and DOC were significantly higher when insects were excluded from the porcine carcass suggesting loss of tissue from larval feeding reduced the mass of nutrients entering the soil. This study provides useful information for forensic science in cases where insect colonization is delayed for a period of time postmortem and soil chemistry in the cadaver decomposition island is considered for estimating postmortem interval.

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

Estimating postmortem interval (PMI) of surface found skeletal remains is challenging. This novel study used UV-Vis-NIR spectroscopy to scan soil collected from cadaver decomposition islands (CDIs) ranging from 15- to 963-d postmortem and control soils. A decomposition product spectra model (DPS model) was constructed by deducting the control soil spectra from the CDI soil spectra for the estimation of postmortem indices: PMI (d), ADD4 , ADD10 , and ADD20 . The DPS model (n=55) was calibrated and subjected to a full cross-validation. Calibration R2 and RPD for the DPS model ranged from 0.97 to 0.99 and from 6.1 to 9.9, respectively, for the four postmortem interval indices. Validation R2 and RPD for the DPS model ranged from 0.73 to 0.80 and from 1.9 to 2.2, respectively. The DPS model estimated postmortem intervals for three test CDIs in a clay soil under perennial grassland (test set 1; n=3) and six CDIs in a sandy soil under a loblolly pine forest (test set 2; n=6). Test set 1 had PMI prediction ranges from -69 to -117days, -796 to +832 ADD4 , +552 to +2672 ADD10 , and -478 to -20 ADD20 of observed PMI. Test set 2 PMI prediction ranged from -198 to -65days, -9923 to +2629 ADD4 , -6724 to +1321 ADD10 , and -2850 to +540 ADD20 of observed PMI. Test set 2 had poor predictions for two CDIs, for all measures of postmortem indices resulting in discussion of sampling depth, effect of body mass index (BMI), and scavenging.

Soil chemical markers distinguishing human and pig decomposition islands: a preliminary study.

The decomposition of vertebrate cadavers on the soil surface produces nutrient-rich fluids that enter the soil profile, leaving clear evidence of the presence of a cadaver decomposition island. Few studies, however, have described soil physicochemistry under human cadavers, or compared the soil between human and non-human animal models. In this study, we sampled soil to 5cm depth at distances of 0cm and 30cm from cadavers, as well as from control sites 90cm distant, from five human and three pig cadavers at the Australian Facility for Taphonomic Experimental Research (AFTER). We found that soil moisture, electrical conductivity, nitrate, ammonium, and total phosphorus were higher in soil directly under cadavers (0cm), with very limited lateral spread beyond 30cm. These patterns lasted up to 700days, indicating that key soil nutrients might be useful markers of the location of the decomposition island for up to 2years. Soil phosphorus was always higher under pigs than humans, suggesting a possible difference in the decomposition and soil processes under these two cadaver types. Our preliminary study highlights the need for further experimental and replicated research to quantify variability in soil properties, and to identify when non-human animals are suitable analogues.

Ultrastructural studies of sensilla in one fly of forensic importance

Taxonomic identification is essential in the field of forensic entomology. Insects are important in the decomposition of cadavers. The flies are generally attracted to cadavers and one of the most important contributions is to estimate the postmortem interval. The scanning electron microscopy (SEM), which allows rapid and accurate identification of different species of forensics flies, has been highlighted as it allows better visualization of the external morphology of immature and some adults. The purpose of this study was to examine in details the morphological aspects of sensilla on the antennae of female and male of Xanthacrona bipustulata Wulp using SEM, since many of them could not be observed just by the use of light microscopy.

Corpse decomposition increases nitrogen pollution and alters the succession of nirK-type denitrifying communities in different water types

Cadaver decomposition as high-quality nutrient inputs may exert strong perturbation on the aquatic environments, such as high nitrogen or nitrate pollution. Denitrifying bacteria may reduce nitrate to nitrogen gas, thereby decreasing the nitrogen pollution and improving self-purification ability of aquatic ecosystem. However, how nirK denitrifying communities in water respond to cadaver decomposition remains unknown. Thus, we employed high-throughput sequencing and chemical analysis to investigate the succession of nirK-type denitrifying communities in tap water and Yellow river water (experimental groups) as well as their corresponding control groups during two important stages of fish corpse decomposition called advanced floating decay and sunken remains. Our data showed that the concentration of NH4+-N in the experimental groups increased approximately 3–4 times compared with the control groups. Proteobacteria was the predominant phylum for nirK denitrifying communities. Several potential pathogenic genera, such as Brucella and Achromobacter, were enriched in the corpse groups. Notably, nirK-type community structures were significantly impacted by cadaver decomposition. Community structures in the corpse groups become more similar with succession, indicating community convergence at the final stage. Water pH, oxidation-reduction potential (ORP) and treatment were three important factors affecting the community structures. However, water type was not a main driving factor determining carcass-associated nirK-type bacterial communities. Four phylogenetic clusters were detected in the denitrifying communities, but showed significantly different distribution between the corpse and control groups. These results provide an in-depth understanding for nirK denitrifying functional bacteria and potential pathogenic bacteria during carrion decomposition process, which offer valuable reference to environmental evaluation and management.

Carrion decomposition and assemblage of necrophagous dipterans associated with Terbufos (Organophosphate) intoxicated rat carcasses

Organophosphate use represents one of the main causes of intentional and accidental poisoning in Brazil. Because they induce alteration in carcass decomposition and succession of necrophagous Diptera, they are important investigative tool in forensic entomology for determining the postmortem interval (PMI) and cause of death. Thus, this work aimed to evaluate the influence of Terbufos, the most commonly used organophosphate for suicides in Rio Grande do Norte, Brazil, in the decomposition process and necrophagous fly assemblies in intoxicated rat carcasses. For this, 150g female Wistar rats received, by gavage, 200µL of Terbufos (5mg/kg or 10mg/kg) or distilled water (control). Approximately 30 minutes after administration, animals were euthanized and distributed in suspended traps to decompose under environmental conditions. Decomposition was monitored daily, with photographic record and collection of the visiting dipterofauna until the dry phase. Data show that the higher dose of Terbufos i) accelerates carcass decomposition in 24h; ii) decreases the species richness and abundance of scavengers flies when compared to the control; iii) changes the succession pattern, delaying the arrival of important species for the PMI estimate and iv) causes 8% mortality of the visiting dipterofauna. This work provides relevant information about dipteran assemblages and changes in the cadaver decomposition process associated with Terbufos intoxication, which may assist in future investigative processes with suspected organophosphate poisoning.

Revolution in death sciences: body farms and taphonomics blooming. A review investigating the advantages, ethical and legal aspects in a Swiss context.

Taphonomy is the study of decaying organisms over time and their process of fossilization. Taphonomy, originally a branch of palaeontology and anthropology, was developed to understand the ecology of a decomposition site, how site ecology changes upon the introduction of plant or animal remains and, in turn, how site ecology affects the decomposition of these materials. In recent years, these goals were incorporated by forensic science to understand the decomposition of human cadavers, to provide a basis on which to estimate postmortem and/or postburial interval, to assist in the determination of cause and circumstances of death, and to aid in the location of clandestine graves. These goals are achieved through the study of the factors that influence cadaver decomposition (e.g. temperature, moisture, insect activity). These studies have also provided insight into the belowground ecology of cadaver breakdown and allowed to develop useful protocols for mass disaster managements in humanitarian medicine. From the results obtained, new scientific disciplines have arisen, gathered under the word "taphonomics" such as the study of microorganisms living below/on a cadaver (thanatogeomicrobiology), and join the more classical forensic sciences such as anthropology, botany or entomology. Taking into account the specificities of the study object (human cadaver), primordial requirements are needed in terms of security (physical and environmental) as well as ethical and legal concerns which are studied in the Swiss context. The present review aims to present in a first part the concept of human forensic taphonomy facilities (HFTF, also colloquially named "body farm") leading to an enrichment of forensic sciences with new "taphonomics". The second part is focused on the mandatory points that must be addressed for a HFTF approach, especially because it requires a specific place to undertake this research which must be performed in conformity with a country's human ethics and laws.

Developing a quantitative method to assess the decomposition of embalmed human cadavers

Embalmed human cadavers are an essential educational tool in forensic science and medicine. Cadavers are often embalmed to extend the period they can be used. Qualitative observations such as odours, tissue texture and colour are the only methods currently used by anatomists to assess the decomposition progress of embalmed cadavers. The aim of this study was to provide a first proof-of-concept to determine whether methylamine, putrescine, and cadaverine could be detected and monitored over time from embalmed human tissues. The hypothesis was that these three compounds would exhibit temporal trends to quantitate progress of decomposition in embalmed cadavers. Two human cadavers were embalmed using McGown solution and liver samples were analysed over 35 days. Liver samples were extracted, homogenised and derivatised to quantify the presence of methylamine, cadaverine and putrescine by gas chromatography - mass spectrometry. All three amines were detected in the tissue samples throughout the duration of the study. Both cadavers had elevated methylamine levels over putrescine and cadaverine at early stages postmortem. This was followed by peaking and reducing in different patterns by the two cadavers; however, the three compounds from a single cadaver changed in a similar pattern. The proposed experimental procedure provides a foundation for further development of quantitative biogenic amine methods to determine decomposition progress in embalmed human cadavers.

Insects Associated to Crime Scenes in the Northeast of Brazil: Consolidation of Collaboration Between Entomologists and Criminal Investigation Institutes.

In Brazil, many studies on Forensic Entomology analyze the activity and succession of flies in animal models. Data on human corpses are always collected and evaluated in isolated cases. This study aimed to list the insect species associated with crime scenes investigated by the Technical-Scientific Institute of criminal expertise of the State of Rio Grande do Norte (ITEP-RN), in the Northeast of Brazil, a region exposed to high homicide rates. In total, 10 cases were investigated, of which 50% were in the initial stage of decomposition. The examined bodies were colonized by species of three orders of insects, Diptera, Coleoptera and Hymenoptera. The order Diptera represented 96% of the total insects, being represented by the following species: Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae), Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae), Chrysomya putoria (Wiedemann) (Diptera: Calliphoridae), and Cochliomyia macellaria, (Fabricius) (Diptera: Calliphoridae); Musca domestica (Linnaeus) (Diptera: Muscidae); and unidentified females of the Sarcophagidae family. Among beetles, the occurrence of Dermestes maculatus (DeGeer) (Coleoptera: Dermestidae), Necrobia rufipes (De Geer) (Coleoptera: Cleridae), and Onthophagus sp. (Scarabaeidae), as well as unidentified specimens of the families Tenebrionidae and Histeridae were recorded. In addition, specimens of Ectatomma sp. (Formicidae) were also recorded. Considering that the Rio Grande do Norte state presents a high homicide rate and the last cadaver study was conducted over a decade ago, these records update the list of species associated with cadaveric decomposition and contribute to consolidate forensic entomology in the Northeast region.

Positive and negative impact to decomposition of pig cadavers by ants (hymenoptera: Formicidae) at the Islet Yeongdo in Busan, South Korea

AbstractWe observed how ants affected the decomposition process of pig cadavers. Experiments were carried out with six pig cadavers during three seasons without winter. Fifteen ant species belonging to 14 genera 3 subfamilies were recorded from pig cadavers. The species richness and species composition of ants were different significantly at bloated and decay stages from the remaining stages, regardless of season. Ant species Nylanderia flavipes, Aphaenogaster japonica, Pheidole fervida, and Ectomomyrmex javanus kept hunting a considerable amount of eggs and maggots of flies in the two stages. In particular, Lasius japonicus continually interrupted landing and ovipositing of flies and removed eggs and maggots from pig cadavers. Our observation suggests that ants may affect decomposition process of dead animals by participating in positive and negative ways by massive removal of eggs and maggots of flies.

Facial reconstruction: Validation of the Tedeschi-Oliveira method for estimating the pronasale point in Brazilians.

Forensic facial reconstruction aids in the process of human identification by facial recognition. The nose plays an important role in this process; however, its soft tissues wither away during cadaveric decomposition. There are few studies in the area of facial recognition of the Brazilian population, especially concerning Brazilian nasal prediction guides. This study aimed to test the hypothesis that the angle formed by the tangents drawn from the rhinion and prosthion points (nose tip) is equal to 90º, as proposed by the pioneer study by Tedeschi-Oliveira et al. (2016). It is important to highlight that this is the only method to date developed to predict the nasal tip in Brazilians, and has not yet been tested in other populations. Images of computed tomography scans of 228 individuals (171 females and 57 males) were screened according to the same criteria used by the authors of the primary study. The images were analyzed using the Horos® program, version 1.1.7 - 64 bit. The mean angle studied was about 90º, and any difference between this mean and the real angle measured did not significantly compromise the accuracy of the nose tip location. The findings tested in the present study corroborate the hypothesis investigated by Tedeschi-Oliveira et. al. Therefore, we suggest that the method be used in forensic practice to estimate nose tips in Brazilians.

Application of HRM-PCR (high resolution melting PCR) for identification of forensically important Coleoptera species

Precise estimation time of death is one of key task of forensic entomology. Especially interesting is Coleofauna present at all stages of cadaver decomposition. The morphological identification of Coleoptera species from varying life stages to species level is time-consuming and needs highly qualified entomologists. Among different molecular methods of species identification very promising is high-resolution melting PCR. It allows fast single-tube assignment of analyzed sample to species based on amplicon melting profile. The object of this study were different specimens of Coleoptera collected at pig cadavers in Łomna (central Poland) during 2012 - 2014. Specimes were identified to species by experts of corresponding Coleoptera families. From 120 collected specimens belonging to four families and twelve species HRM-PCR correctly identified specimens belonging to three families and eight species.

Fungal succession during mammalian cadaver decomposition and potential forensic implications

The necrobiome is the postmortem community that includes bacteria, fungi, arthropods, and other cadaver-associated organisms. It has been suggested as biological evidence for forensic investigation. Fungi form distinctive mildew spots in colonizing decomposing bodies, converting them into moldy cadavers. However, the postmortem fungal community consists of more than these visible species. Characterizing the succession pattern of the fungal community during decomposition is valuable not only for understanding the ecosystem composition of the cadaver decomposition islands but also for contributing to forensic investigations. In the present study, the fungal composition of pig cadavers and succession patterns during decomposition were investigated with high-throughput sequencing. The succession patterns were easier to discern in outdoor cadavers, compared with those that were placed indoors. The metabarcoding approach revealed trends linking particular fungal taxa with specific postmortem intervals (PMIs). Dominant species increased notably in cadavers and soil. Furthermore, the succession of the soil community was driven by the cadaver decomposition. Significant mycoflora differences were observed between environmental and cadaveric soil. The results obtained suggested that postputrefaction mycoflora have considerable potential for PMI estimation, particularly in cases that involve heavily decomposed bodies. In addition, the diversity of fungal communities revealed by the metabarcoding approach allowed us to discriminate the sites of cadaver decomposition, implying that postputrefaction mycoflora may be helpful in identifying the environment in which a cadaver has been placed, or the original location from which a cadaver has been moved. Our results provide an important step towards developing fungal evidence for use in forensic science and add to the growing body of work on postmortem microbial communities.

Volatile Organic Compound Profiling from Postmortem Microbes using Gas Chromatography-Mass Spectrometry.

Volatile organic compounds (VOCs) are by-products of cadaveric decomposition and are responsible for the odor associated with decomposing remains. The direct link between VOC production and individual postmortem microbes has not been well characterized experimentally. The purpose of this study was to profile VOCs released from three postmortem bacterial isolates (Bacillus subtilis, Ignatzschineria indica, I.ureiclastica) using solid-phase microextraction arrow (SPME Arrow) and gas chromatography-mass spectrometry (GC-MS). Species were inoculated in headspace vials on Standard Nutrient Agar and monitored over 5days at 24°C. Each species exhibited a different VOC profile that included common decomposition VOCs. VOCs exhibited upward or downward temporal trends over time. Ignatzschineria indica produced a large amount of dimethyldisulfide. Other compounds of interest included alcohols, aldehydes, aromatics, and ketones. This provides foundational data to link decomposition odor with specific postmortem microbes to improve understanding of underlying mechanisms for decomposition VOC production.

“From womb to tomb; we’re bound to others”: microbiome in forensic science

Microbiome is a new field of interest in clinical medicine with high potential in forensic medicine. It could be used in several applications, such as post-mortem interval (PMI) estimation, personal identification, differential diagnosis of cause of death and toxicology. Regarding PMI, during the decomposition of a corpse, the passage of time involves changing in microbial population both outside and inside the corpse but also in surrounding soil (cadaver decomposition island). These variations could be hypothetically used as PMI indicators (microbial clock), even thanks to the development of machine learning approach. Another potential use of skin and saliva microbiome is personal identification thanks to its inter-individual variability and tendency to remain unvarying over time. It may also be helpful to link a person to a specific object that has been touched (microbial fingerprint). Furthermore, we could infer some information about health state of human subjects, comparing post-mortem and ante-mortem microbiome, but this field of research is quite new and needs further studies. Moreover, we have to consider the influence of microbiome metabolism in post-mortem toxicological evaluation; microbes could alter substances concentrations – for example of ethanol, gamma-hydroxybutyric acid (GHB) and nitrobenzodiazepines – due to enzymatic degradation and individual microbial metabolism. Finally, integration of microbiome and human being’s transcriptomic analysis may be helpful to depict their complex interactions even after death.

Decomposition and insect colonization patterns of pig cadavers lying on forest soil and suspended above ground.

Hanging is one of the most common methods of suicide, and, although it is known that decomposition and patterns of insect fauna colonization of hanging cadavers differ from those of cadavers decomposing on the ground, these differences have only been sparsely studied in Europe so far. We studied the decomposition and insect colonization patterns of ten pig (Sus scrofa domestica) carcasses in a spruce forest near Neuchâtel, Switzerland, over a 32-day period in summer 2013 (July 1st - August 2nd). Five pig carcasses were suspended horizontally in metal cages one meter above the ground and five carcasses were placed directly on the ground. The species occurrence and abundance of Coleoptera and Diptera recovered from passive pitfall traps and collected manually on the carcasses were recorded. Indicator species of decomposition stages and suspended vs. ground cadavers were identified by Indicator Value (IndVal) analysis. The ground carcasses decomposed significantly faster than the suspended carcasses. Coleoptera and Diptera communities differed significantly over time, between treatment, and the treatment effect varied over time. Diptera were evenly distributed among the two treatments. Coleoptera were more abundant and less differentiated on the ground carcasses and represent better indicators of cadavers decomposing on the soil as well as decomposition stages. Our results suggest possible applications such as evaluating if a hanged cadaver has been dropped to the ground, or inversely if a cadaver first lying on the soil has later been hung to fake a suicide. However differences among studies suggest possible effects of meso-climate determined by habitat which should be explored further.