Decomposition Of Human Remains Research Articles

Post-mortem Interval estimate based on dental pulp: A histomorphology approach.

Estimating the post-mortem interval (PMI) of human remains based on the histomorphology of dental pulp parameters is promising, but available evidence is scarce and sometimes contradictory without a scientific model. The aim of the study is to characterise the histomorphological changes of dental pulp associated with the decomposition of human remains by a qualitative and quantitative approach. The main aim is to establish a correlation based on post-mortem (PM) dental pulp histomorphology and the PMI, and whether pulp degradation could be an available medico-legal tool for PMI estimation beyond the first week after death (late PMI). The eligible sample consisted of 27 sound teeth from 16 healthy patients aged 16 to 72 years due to orthodontic or oral surgery treatment, to create PMI's simulating the death of the subject as the time elapsed from tooth avulsion. Data collected from patients (sex, date of birth, tooth position, date and hour of the avulsion, date and hour of pulp extraction) were anonymised in accordance with the requirements of Faculty of Dental Medicine of the University of Lisbon. The sample was divided into 9 groups of 3 teeth according to different PMI sets from T0 (baseline) up to 2 weeks (T0, 7, 12, 24, 36, 48, and 72 hours, 1 and 2 weeks). All the dental samples were stored at room temperature up to the time of pulp extraction and then prepared with haematoxylin and eosin stain. High-resolution microscopy was performed to obtain histological images. An operator performed the qualitative evaluation of blood vessels, collagen fibres, and the extra-cellular matrix (ECM) in PM pulps and measured the variation in cells/nuclei density by counting 6 different ROIs (Regions of Interest) for each pulp manually and automatically (quantitative analysis). Qualitative results showed that the degeneration of dental pulp appears 7 hours after death but histological changes in vessels, fibres, and ECM in PM dental pulp are characterised by high variability, consequently it is not possible to generalise the results for early PMIs. Quantitative measurements proved that cell count cannot be standardised due to the presence of superimposed layers of cells and nuclei fragmentation. Odontoblasts did not demonstrate evidence of cellular or nuclear lysis up to 14 PM suggesting their applicability in late PMIs. Future research will focus on late PMIs and different techniques of tooth preparation.

Research Progress of Using Canine Olfactory Search for Human Remains.

In the process of murder investigation, it is of great significance to find the discarded and buried human remains accurately. The main methods of searching for human remains include human visual search, aerial detection, geophysical technology, remote imaging technology and canine olfactory search technique. Canine olfactory search for human remains is a recognized time-effective and non-invasive search method, making dogs the most valuable search tool in forensic investigation. By systematically reviewing and summarizing relevant literature, and based on the theory of volatile organic compound produced by the decomposition of human remains, this paper explores the basic principle of the canine olfactory search technique for human remains. This paper also reviews the application of training canine search technique for human remains in forensic investigation by using human blood, tissue, cadaver putrefying fluid and odor substitutes as sniffing sources. The application prospect of canine olfactory search for human remains was prospected from the perspectives of detection of volatile organic compound during cadaver decay, development of odor substitutes and adsorption devices, and technology tactics used in canine training and use, to provide references for the relevant research of canine olfactory search for human remains in China.

The taphonomic impact of scavenger guilds in southern Quebec during summer and fall in two distinct habitats.

Decomposition of human remains is a complex process impacted by many intrinsic and extrinsic factors. A less-studied extrinsic factor in forensic taphonomy are the scavengers that consume soft and hard tissue. Scavengers physically degrade and remove soft tissue, disperse, and destroy skeletal elements, which can make locating remains challenging. While invertebrate activity has been largely investigated, there is limited quantitative data available on vertebrate activity, particularly in Canada. This study aimed to determine which species (vertebrate and invertebrate) belong to the scavenger guilds in southern Quebec, and their potential taphonomic impact on the decomposition process. Two independent trials were conducted in 2020 using pig carcasses: one during summer in a forest habitat and one during fall in a grassland habitat. Each carcass was placed a minimum 100m apart in semi-rural land. Vertebrate scavenger activity was recorded by continuous surveillance using trail cameras. Carcasses were also regularly visited to monitor the decomposition process and the activity of invertebrate scavengers. Overall, the vertebrate scavenger guilds included a narrow range of corvids, turkey vultures, coyotes, and skunks. The intensity of vertebrate scavengers was greater in the grassland habitat (fall), while the intensity of invertebrate scavengers was greater in the forest habitat (summer). With the exception of invertebrate scavengers, very few species visited during the fresh stage of decomposition, and the probability of body displacement increased as decomposition progressed. These results identify which scavengers have the greatest taphonomic impact and highlight the importance of incorporating scavenger impact when searching for human remains.

Decomposition of human remains in acid; pig trotters in various concentrations of hydrochloric acid

Decomposition of human remains in acid; pig trotters in various concentrations of hydrochloric acid

Temperature Influence on Prevailing Necrophagous Diptera and Bacterial Taxa With Forensic Implications for Postmortem Interval Estimation: A Review.

The decomposition process of human (and other mammalian) remains is influenced by numerous factors such as the environmental temperature, relative humidity, precipitation, geographical location of the remains, as well as the medical conditions of and any injuries sustained by the deceased person. The decomposition process generally follows a consistent pattern (fresh, bloat, active decomposition, advanced decomposition, and dry stage). Understanding the time-span of each stage of decomposition and the influence of the biotic and abiotic factors involved is imperative when trying to estimate the time elapsed since death (postmortem interval [PMI]). Over the course of decomposition, the tissues are gradually consumed by necrophagous insects and bacteria. The environmental temperature and its variations influence how insects colonize the remains, having a significant impact on their presence and developmental cycle. Additionally, the bacterial community colonizing decomposing tissues is also greatly affected by variations in environmental temperature. Because both the rate of decomposition of human remains and the relative abundance of certain insects and bacterial species are all temperature-dependent, insect and bacterial colonization data are useful as key points for the PMI estimation. This article reviews the current literature documenting the data collected on the occurrence and development cycles of predominant necrophagous Diptera (Calliphoridae, Muscidae, Sarcophagidae) and bacterial taxa involved in the decomposition of various carcasses at different temperatures. This review will impact the forensic community by providing an overview on the temperature, insect and bacterial records for the PMI estimation, seeking to aid forensic entomologists, microbiologists, pathologists, and the legal community.

Short-term effects of hydrated lime and quicklime on the decay of human remains using pig cadavers as human body analogues: Laboratory experiments

Contradictions and misconceptions regarding the effect of lime on the decay of human remains have demonstrated the need for more research into the effect of different types of lime on cadaver decomposition. This study follows previous research by the authors who have investigated the effect of lime on the decomposition of human remains in burial environments. A further three pig carcasses (Sus scrofa), used as human body analogues, were observed and monitored for 78 days without lime, with hydrated lime (Ca(OH)2) and with quicklime (CaO) in the taphonomy laboratory at the University of Bradford. The results showed that in the early stages of decay, the unlimed and hydrated lime cadavers follow a similar pattern of changes. In contrast, the application of quicklime instigated an initial acceleration of decay. Microbial investigation demonstrated that the presence of lime does not eliminate all aerobic bacteria. The experiment also suggested that lime functions as a sink, buffering the carbon dioxide evolution. This study complements the field observations. It has implications for the investigation of time since death of limed remains. Knowledge of the effects of lime on decomposition processes is of interest to forensic pathologists, archaeologists, humanitarian organisations and those concerned with disposal of animal carcasses or human remains in mass disasters.

Spatio-temporal variation of trace element contents in Rwanda necrosols

In this study, the spatio-temporal variation of selected trace elements in cemetery soils (necrosols) was investigated. Preliminary results revealed that onsite mean concentration for As, Ba, Cr, Cs, Ga, Ni, Rb, Sc, Th, V, Y, and Zr was generally higher than background offsite values. The trace metal contents of the cemetery soils also showed higher accumulation ratio for As, Cr, Ni, and Sc relative to world averages for soils (Clarke values). Similarly, it was observed that the cemetery soils showed significant enrichment with As and Cr in comparison with world averages for agricultural soils. The exchangeable sodium percentage showed that most of the onsite soil samples are sodic, which may have adverse effect on the growth and yield of crops grown in the study area. The study concludes that decomposition of human remains and grave contents play a significant role in elevating the total trace element contents in soils associated with cemeteries. For this reason, there is need for proactive measures to be taken with respect to the choice of raw materials used for the construction of coffins and funeral materials. There is need for local funeral industries particularly in developing countries and the government to begin to consider and adopt such green or environmental friendly burial options to prevent the potential environmental degradation of cemetery areas.

Soil temperature calculation for burial site analysis

The effect of air and water temperature upon the decomposition of human remains and upon biological activity has been extensively studied. However, less attention has been devoted to the temperature of the soil surrounding burials, despite its potential influence upon chemical reactions involved in the decomposition of human remains, drugs and toxins, as well as upon microbial and insect activity. A soil temperature calculation equation usually employed in civil engineering was used to calculate soil temperature at various depths in a cemetery located in Brisbane, Australia, in order to explain the extensive degradation of human remains and funerary objects observed at exhumation. The results showed that for the 160 years of the site's history, ground temperature at burial level had been sufficiently high for biological activity and chemical degradation reactions to continue right up until the time of exhumation. The equation used has potential in the analysis of both cemetery and clandestine burials, since it allows ground temperature to be calculated from ambient air temperature figures, for a variety of depths, soil types and vegetation conditions.

Modelling the buried human body environment in upland climes using three contrasting field sites

Despite an increasing literature on the decomposition of human remains, whether buried or exposed, it is important to recognise the role of specific microenvironments which can either trigger or delay the rate of decomposition. Recent casework in Northern England involving buried and partially buried human remains has demonstrated a need for a more detailed understanding of the effect of contrasting site conditions on cadaver decomposition and on the microenvironment created within the grave itself. Pigs ( Sus scrofa) were used as body analogues in three inter-related taphonomy experiments to examine differential decomposition of buried human remains. They were buried at three contrasting field sites (pasture, moorland, and deciduous woodland) within a 15 km radius of the University of Bradford, West Yorkshire, UK. Changes to the buried body and the effect of these changes on hair and associated death-scene textile materials were monitored as was the microenvironment of the grave. At recovery, 6, 12 and 24 months post-burial, the extent of soft tissue decomposition was recorded and samples of fat and soil were collected for gas chromatography mass spectrometry (GCMS) analysis. The results of these studies demonstrated that (1) soil conditions at these three burial sites has a marked effect on the condition of the buried body but even within a single site variation can occur; (2) the process of soft tissue decomposition modifies the localised burial microenvironment in terms of microbiological load, pH, moisture and changes in redox status. These observations have widespread application for the investigation of clandestine burial and time since deposition, and in understanding changes within the burial microenvironment that may impact on biomaterials such as hair and other associated death scene materials.

Decomposition Chemistry of Human Remains: A New Methodology for Determining the Postmortem Interval

This study was conducted to characterize the chemistry associated with the decomposition of human remains with the objective of identifying time-dependent biomarkers of decomposition. The purpose of this work was to develop an accurate and precise method for measuring the postmortem interval (PMI) of human remains. Eighteen subjects were placed within a decay research facility throughout a four-year time period and allowed to decompose naturally. Field autopsies were performed and tissue samples were regularly collected until the tissues decomposed to the point where they were no longer recognizable (encompassing a cumulative degree hour (CDH) range of approximately 1000 (approximately 3 weeks)). Analysis of the biomarkers (amino acids, neurotransmitters, and decompositional by-products) in various organs (liver, kidney, heart, brain, muscle) revealed distinct patterns useful for determining the PMI when based on CDHs. Proper use of the methods described herein allow for PMIs so accurate that the estimate is limited by the ability to obtain correct temperature data at a crime scene rather than sample variability.