Can we infer post mortem interval on the basis of decomposition rate? A case from a Portuguese cemetery

Developing a new scoring method to evaluate human decomposition in a humid, continental (Dfb) climate in Quebec

The published literature shows a lack of methods to evaluate the patterns and extent of decomposition of human remains and to estimate the post-mortem interval (PMI) in humid, continental (Dfb) climates such as Quebec. The aim of this study was to address this gap in the current knowledge base by providing the first observations from human corpses studied under controlled conditions in Quebec. A 12-month study was conducted at the site for Research in Experimental and Social Thanatology; the first human taphonomy facility in Canada. Six human donors with known time of death were deposited across spring (n = 1), summer (n = 3), and autumn (n = 2) 2021. The lack of suitability of the total body score method to evaluate the extent of decomposition at the facility prompted the development of a new scoring system based on the macromorphoscopic changes observed. The scoring system was applied to the donors to evaluate decomposition throughout seasons. All donors followed comparable decomposition trajectories, regardless of the season of deposition. Eighty-five percent of taphonomic patterns appeared in the first 25 experimental days or 5000 Kelvin accumulated degree days (350 ADD). Extensive desiccation of tissues was observed at a median of 21 experimental days across donors, resulting in a plateau within decomposition with no extensive skeletonization. To the authors' knowledge, this is the first published report of experimentally observed desiccation in such a form in a Dfb climate. This study provides new data on the types of decomposition patterns to expect in forensic investigations in southern Quebec and comparable climates.

Recommendations for large-scale exhumations of Potter's Fields: Cases in the US

Increased commitment to humanitarian identification and advances in DNA technology contribute to growing interest in large scale identification operations for unidentified, interred remains. However, scant literature discusses the practical challenges in conducting cemetery exhumations en masse for the purposes of DNA sampling and reinterment. This paper draws on a case study of cemetery exhumations conducted in the US as part of a multi-agency, multi-year endeavor, Operation UNITED. Challenges and strategies for managing logistics and manpower, locating human remains in active cemeteries, and overcoming containment and preservation issues of adult and juvenile remains are presented. This paper evidences the potential for investigation into cemetery exhumation strategies to assist in effective humanitarian identification.

Determination of Empirical Environmental Indices for the Location of Cemeteries—An Innovative Proposal for Worldwide Use

Cemeteries are a source of environmental contamination, as they hold hundreds of human corpses in different stages of decomposition. Therefore, the current research developed a new tool, which is easily applied, to determine the potential environmental contamination generated by current cemeteries within their ecosystems. The linear equations developed, with a number of variables between 10 and 3, allow for obtaining empirical indices to evaluate the suitability of a site, regardless of the geographical area in which it is located, through a variety of sources. In order to obtain the equations and, therefore, the indices, a hierarchy was performed using the Saaty matrix. With such a matrix, different ranges of affectation were established for each variable and relative values were assigned that cover all probabilities quantitatively, from the least probable to the most likely. With the linear equations, three verification runs were conducted, obtaining satisfactory results compared with the location map of cemeteries obtained in previous studies. These equations will constitute a tool of fundamental use for local governments, which will allow for the evaluation of existing cemeteries and use of the methodology described in preliminary analysis, to save resources and have a starting point for an efficient land use plan.

Decomposition variability between the scene and autopsy examination and implications for post-mortem interval estimations

Forensic experts rely on scene and/or autopsy photographs to estimate the post-mortem interval (PMI) when an in-situ assessment of decomposition is unfeasible. The degree of decomposition may vary between the scene and autopsy, which importantly could affect estimations of the unknown PMI in forensic casework. This study aimed to investigate decomposition variability between the scene and autopsy and assess the subsequent effect on the accuracy of PMI estimations. Scene and autopsy photographs from 94 cases with known PMI were used from the Allegheny County Office of the Medical Examiner in Pittsburgh, United States. The total decomposition scoring (TDS) method measured the overall decomposition level, and 28 markers of decomposition were recorded as a percentage of the total body surface area (TBSA). In 60% of cases the TDS had increased at autopsy causing significant overestimations of the autopsy PMI and 86% of decomposition markers varied between the scene and autopsy. Decomposition progressed during mortuary time lags (MTL) of 3-44 h, where bodies were stored in a pre-autopsy refrigerator at 4 °C, suggesting that refrigeration may not always delay decomposition. This research also assisted in validating photographs as a proxy for real-time decomposition assessments. While the autopsy photographs conferred higher quality than the scene photographs, the scene photographs produced more accurate PMI estimations. Forensic experts should exhibit caution when estimating the PMI from autopsy photographs alone, as they may not accurately reflect scene decomposition. To prevent misinterpretation of the PMI estimation, both scene and autopsy photographs should always be requested.

The Identified Skeleton Collection of Évora: importance for forensic science and bioarchaeology in the southern inland of Portugal

The importance of reference osteological collections is unquestionable. However, the development of methodologies is more reliable the closer the collection is socioeconomically, demographically, and genetically to the population under study. The purpose of this study is to characterize and contextualize a new Portuguese reference collection. The collection of identified skeletons from the University of Évora comprises 201 adults of both sexes and seven non-adults, deceased between 1870 and 1993 and born between 1790 and 1969. It consists almost exclusively of individuals who were born and died in inland Alentejo, being the only Portuguese collection with this characteristic. The collection was built following all current legal and ethical obligations. Due to its characteristics, the collection constitutes a fundamental tool for forensic and bioarchaeological research in the inland regions of Portugal. In addition to the possibility offered to develop and validate methodologies in both sciences, the available complete hospital archives for research make this collection unique for health studies before, during, and after the epidemiological transition.

The Effect of Different Coverings on Total Body Score Development of Buried Carcasses

Background

Examination of post-mortem changes is one of the ways to assess decomposition process on buried bodies. Nonetheless, studies on such assessment are still lacking, especially on the effects of body coverings by different materials in burial conditions. The aim of this research is to study the effect of different types of covering towards decomposition on buried rabbit carcasses by using Total Body Score (TBS) system.

Methods

Twenty-seven rabbit carcasses were divided into: (i) No Clothing; (ii) Thick Clothing and (iii) Plastic Wrapping groups, and buried into individual shallow graves. One subject was exhumed from first to ninth post-burial week and assessed by using TBS system.

Results and Discussion

There are significant differences among TBS between different coverings while controlling the time factor, F (2, 23) = 4.80, P < 0.05, partial η² = 0.294. TBS score for Plastic Wrapping group is significantly lower than No Clothing group over times at α = 0.05, P < 0.05. The slightly delaying effect of thick clothing is caused by design of jacket, which allows arthropods access and microbial activity. Relatively strong delaying effect by plastic covering could be caused by impermeable property that caused accumulation of decompositional products and slow down the degradation.

Conclusion

In conclusion, TBS system is a potential tool in describing rate of decomposition for buried cases in Malaysia.

A practical review of adipocere: Key findings, case studies and operational considerations from crime scene to autopsy

After death, the body begins decomposition, a process that starts with the breakdown of organic matter and typically leads to the complete degradation of a body. Such a process is highly affected by (micro and macro) environmental factors of intrinsic and extrinsic nature. Adipocere is a substance formed from the decomposition of adipose tissue and represents a disruption to the typical decomposition process. Such disruption causes decomposition to slow or arrest completely, placing a body into a state of preservation, and determines complications in the estimation of the time since death (Post-Mortem Interval, PMI). While several studies have been performed on the nature, the formation and the degradation of adipocere, there is still no reliable model to assess the PMI of a body exhibiting it. Case studies are an important source to aid pathologists and investigators during a case. This review presents a summary and an update on the knowledge surrounding the chemistry and the factors affecting adipocere formation and degradation, the timing and the distribution of adipocere throughout a body, and the techniques used to investigate it. Furthermore, a table of the most important case studies involving adipocere since 1950, several images and descriptions of recent cases and operational considerations for the best practice at the crime scene and autopsy are presented to be used as a reference to facilitate forensic professionals in adipocere cases.

Perspectives on the establishment of a canadian human taphonomic facility: The experience of REST[ES]

REST[ES] is the first Canadian human taphonomic facility (HTF) dedicated to research and training relating to human decomposition in a northern temperate climate. The following paper outlines the measures taken to successfully establish, open and operate this novel Canadian HTF with particular focus on: project team and partnerships, facility location, approvals and permits, infrastructure and social acceptability. It is intended that our experience of establishing REST[ES] may serve as an example to help others with the establishment of future HTFs, thus contributing to the expansion in the global accessibility to human decomposition research and training.

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Establishment experience of REST[ES].

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Difficulties with government approbations.

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Facility infrastructure, health and security measures.

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Body donation program and requirements.

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Social acceptability initiatives.

New data about the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal)

After the publication of the first article in 2014, 21st Century Identified Skeletal Collection, housed in the Laboratory of Forensic Anthropology, Department of Life Sciences at the University of Coimbra, Portugal, has been growing. Currently, the collection is composed of 302 complete adult skeletons of both sexes, which means that in 5 years it has doubled. The collection consists mostly of elderly individuals, with only 12.25% of the individuals aged less than 61 years old. All individuals are Portuguese nationals who died between 1982 and 2012. Ninety individuals exhibit prostheses, other medical devices and signs of surgical procedures. Moreover, a sub-collection of experimentally burned skeletons is under development, and currently includes 56 individuals (18.54% of the collection). The 21st Century Identified Skeletal Collection constitutes a fundamental tool for forensic anthropology research, including the development and validation studies of methods that focus on elderly individuals, as can be ascertained by the numerous scientific publications and academic scholarship that have been produced in previous years.

Forensic taphonomy: Vertebrate scavenging in the temperate southwestern Cape, South Africa

Vertebrate scavenging can significantly accelerate the rate of decomposition, which can hinder estimating the post-mortem interval (PMI). Patterns of decomposition and scavenging are highly specific to different environments in a forensic context, with no known data for South Africa. A better understanding of local decomposition patterns, taking scavenging into account, could increase the accuracy of PMI estimation and improve identification of human remains. Using a porcine model in the forensically significant thicketed Cape Flats Dune Strandveld habitat, the effect of vertebrate scavenging on the decomposition process was examined. This part of Cape Town suffers from poor socioeconomic conditions and a high murder rate, which is due in part to the dense population. Human decomposition was simulated using three small (∼20kg) domestic pig (Sus scrofa domesticus) carcasses, with ethical clearance. One pig served as a control and was caged to prevent vertebrate but not invertebrate access; the other two served as experimental treatments. They were deployed in Delft, Cape Town, and observed by motion-activated, time-lapse remote photography to record scavenger species and activity. A rapid increase in the decomposition rate was observed due to Cape grey mongoose (Galerella pulverulenta) scavenging, with early skeletonisation reached by both experimental pigs by day 14, compared to the control remaining in advanced decomposition after 93 days. Mongoose is the primary scavenger in this habitat, and showed notable patterns of feeding behaviour, exclusively within daylight hours. Scavenging activity was only influenced by rainfall later in the cycle. This research provides knowledge on locally relevant decomposition patterns and highlights the necessity for PMI estimation methods to consider vertebrate scavengers. This may improve human skeletal identification in forensic cases. There is scope for expansion of this study, with an investigation of seasonal effects, the interaction between invertebrate and vertebrate activity, as well as, the effect of clothing on scavenger access.

A computational approach to estimate postmortem interval using opacity development of eye for human subjects

This paper presents an approach to postmortem interval (PMI) estimation, which is a very debated and complicated area of forensic science. Most of the reported methods to determine PMI in the literature are not practical because of the need for skilled persons and significant amounts of time, and give unsatisfactory results. Additionally, the error margin of PMI estimation increases proportionally with elapsed time after death. It is crucial to develop practical PMI estimation methods for forensic science. In this study, a computational system is developed to determine the PMI of human subjects by investigating postmortem opacity development of the eye. Relevant features from the eye images were extracted using image processing techniques to reflect gradual opacity development. The features were then investigated to predict the time after death using machine learning methods. The experimental results prove that the development of opacity can be utilized as a practical computational tool to determine PMI for human subjects.

Gene expression in the twilight of death: The increase of thousands of transcripts has implications to transplantation, cancer, and forensic research

After a vertebrate dies, many of its organ systems, tissues, and cells remain functional while its body no longer works as a whole. We define this state as the "twilight of death" - the transition from a living body to a decomposed corpse. We claim that the study of the twilight of death is important to ethical, legal and medical science. We examined gene expression at the twilight of death in the zebrafish and mouse reaching the conclusion that apparently thousands of transcripts significantly increase in abundance from life to several hours/days postmortem relative to live controls. Transcript dynamics of different genes provided "proof-of-principle" that models accurately predict an individual's elapsed-time-of-death (i.e. postmortem interval). While many transcripts were associated with survival and stress compensation, others were associated with epigenetic factors, developmental control, and cancer. Future studies are needed to determine whether the high incidence of cancer in transplant recipients is due to the postmortem processes in donor organs.

Systematic analysis of gene expression patterns associated with postmortem interval in human tissues

Postmortem mRNA degradation is considered to be the major concern in gene expression research utilizing human postmortem tissues. A key factor in this process is the postmortem interval (PMI), which is defined as the interval between death and sample collection. However, global patterns of postmortem mRNA degradation at individual gene levels across diverse human tissues remain largely unknown. In this study, we performed a systematic analysis of alteration of gene expression associated with PMI in human tissues. From the Genotype-Tissue Expression (GTEx) database, we evaluated gene expression levels of 2,016 high-quality postmortem samples from 316 donors of European descent, with PMI ranging from 1 to 27 hours. We found that PMI-related mRNA degradation is tissue-specific, gene-specific, and even genotype-dependent, thus drawing a more comprehensive picture of PMI-associated gene expression across diverse human tissues. Additionally, we also identified 266 differentially variable (DV) genes, such as DEFB4B and IFNG, whose expression is significantly dispersed between short PMI (S-PMI) and long PMI (L-PMI) groups. In summary, our analyses provide a comprehensive profile of PMI-associated gene expression, which will help interpret gene expression patterns in the evaluation of postmortem tissues.

The Effect of Body Mass on Outdoor Adult Human Decomposition

Forensic taphonomy explores factors impacting human decomposition. This study investigated the effect of body mass on the rate and pattern of adult human decomposition. Nine males and three females aged 49-95 years ranging in mass from 73 to 159 kg who were donated to the Complex for Forensic Anthropology Research between December 2012 and September 2015 were included in this study. Kelvin accumulated degree days (KADD) were used to assess the thermal energy required for subjects to reach several total body score (TBS) thresholds: early decomposition (TBS ≥6.0), TBS ≥12.5, advanced decomposition (TBS ≥19.0), TBS ≥23.0, and skeletonization (TBS ≥27.0). Results indicate no significant correlation between body mass and KADD at any TBS threshold. Body mass accounted for up to 24.0% of variation in decomposition rate depending on stage, and minor differences in decomposition pattern were observed. Body mass likely has a minimal impact on postmortem interval estimation.

Luminol chemiluminescence: contribution to postmortem interval determination of skeletonized remains in Portuguese forensic context

Postmortem interval (PMI) determination is one of the main challenges of forensic anthropology, and there are several referenced methods that consider intrinsic and extrinsic factors to the skeletonized remains. Therefore, there is an important need to develop a precise, economic, easy and reproducible technique, which will operate as a presumptive test. The chemical reaction that occurs in the presence of luminol, chemiluminescence, is used as a work tool to evaluate the PMI. This is given by luminol high affinity for haemoglobin, which is secured in bone tissue by its high mineral content, after the blood supply ceases postmortem. We evaluated a luminol-based technique, in which we measured the chemiluminescence of skeletonized remains as an indicator of the PMI. We assessed the usage of this technique for PMI estimation and for deciding whether remains have forensic interest, particularly in the Portuguese medicolegal context. Additionally, we evaluate the reproducibility of this technique. The test sample consists of 50 skeletonized individuals of both sexes, adults, between 20 and 98 years, with a known time since death and without bone pathologies. The results of Kappa statistic, with values between 0.79 and 0.97, showed high interobserver and intraobserver agreement when applying the luminol test as a presumption test. We concluded that this technique alone is not precise and of limited value to determine forensic relevance in the Portuguese context. However, it can be used as a presumptive test, reducing time and costs in criminal investigation.

The Veterinary Forensic Necropsy: A Review of Procedures and Protocols

Investigation of animal-related crime, and therefore submission of forensic cases to veterinary pathology facilities, is increasing, yet many veterinary pathologists are unfamiliar and often uncomfortable with involvement in the forensic necropsy. This article discusses various aspects of the forensic necropsy without specific attention to any particular species group or crime. General advice is given on procedures, documentation, and recording of the examination, and the article indicates how these features may differ from those used in investigation of natural disease. It also discusses evidence management, including recordkeeping, identification of evidence, labeling of photographs, and use of standard operating procedures and protocols. Various written and visual methods for documentation of the forensic necropsy are covered, and adjunctive topics such as sample collection, assessment, and description of wounds and taphonomy are included. Cause, mechanism, and manner of death are defined, and guidance to the use of these terms is given. The aim of this article is to offer guidance on procedural aspects of the forensic necropsy that will help those developing their forensic services, contribute to standardization of the provision of forensic veterinary pathology, and build the confidence of the "uncomfortable" forensic veterinary pathologist.

A novel approach to determine post mortem interval using neutron radiography

One of the most difficult challenges in forensic research is to objectively determine the post-mortem interval (PMI). The accuracy of PMI is critical for determining the timeline of events surrounding a death. Most PMI techniques rely on gross morphological changes of cadavers that are highly sensitive to taphonomic factors. Recent studies have demonstrated that even exhumed individuals exposed to the same environmental conditions with similar PMIs can present different stages of decomposition. After death, tissue undergoes sequential changes consisting of organic and inorganic phase variations, as well as a gradual reduction of tissue water content. Hydrogen (H) is the primary contributor to neutron radiography (NR) contrast in biological specimens because (1) it is the most abundant element in biological tissues and (2) its nucleus scatters thermal and cold neutrons more strongly than any other atomic nucleus. These contrast differences can be advantageous in a forensic context to determine small changes in hydrogen concentrations. Neutron radiography of decaying canine tissues was performed to evaluate the PMI by measuring the changes in H content. In this study, dog cadavers were used as a model for human cadavers. Canine tissues and cadavers were exposed to controlled (laboratory settings, at the University of Tennessee, College of Veterinary Medicine) and uncontrolled (University of Tennessee Anthropology Research Facility) environmental conditions, respectively. Neutron radiographs were supplemented with photographs and histology data to assess the decompositional stages of cadavers. Results demonstrated that the increase in neutron transmission likely corresponded to a decrease in hydrogen content in the tissue, which was correlated with the decay time of the tissue. Tissues depleted in hydrogen were brighter in the neutron transmission radiographs of skeletal muscles, lung, and bone, under controlled conditions. Over a period of 10 days, changes in neutron transmission through lung and muscle were found to be higher than bone by 8.3%, 7.0%, and 2.0%, respectively. Results measured during uncontrolled conditions were more difficult to assess and further studies are necessary. In conclusion, neutron radiography may be used to detect changes in hydrogen abundance that can be correlated with the post-mortem interval.

Normal pediatric postmortem CT appearances

Postmortem radiology is a rapidly developing specialty that is increasingly used as an adjunct to or substitute for conventional autopsy. The goal is to find patterns of disease and possibly the cause of death. Postmortem CT images bring to light processes of decomposition most radiologists are unfamiliar with. These postmortem changes, such as the formation of gas and edema, should not be mistaken for pathological processes that occur in living persons. In this review we discuss the normal postmortem thoraco-abdominal changes and how these appear on CT images, as well as how to differentiate these findings from those of pathological processes.

Investigating the Postmortem Molecular Biology of Cartilage and its Potential Forensic Applications

This study investigated the postmortem molecular changes that articular cartilage undergoes following burial. Fresh pig trotters were interred in 30-cm-deep graves at two distinct locations exhibiting dissimilar soil environments for up to 42 days. Extracts of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joint cartilage from trotters disinterred weekly over 6 weeks were analyzed by Western blot against the monoclonal antibody 2-B-6 to assess aggrecan degradation. In both soil conditions, aggrecan degradation by-products of decreasing molecular size and complexity were observed up to 21 days postmortem. Degradation products were undetected after this time and coincided with MCP/MTP joint exposure to the soil environment. These results show that cartilage proteoglycans undergo an ordered molecular breakdown, the analysis of which may have forensic applications. This model may prove useful for use as a human model and for forensic investigations concerning crimes against animals and the mortality of endangered species.

Promising blood-derived biomarkers for estimation of the postmortem interval

A linear correlation between blood putrefaction time and biochemical parameter concentrations was obtained. Two mathematical models that may have predictive value for estimation of thepostmorteminterval were developed. The obtained results might be complementary procedures for the methodologies already used.

Where do those remains come from?

Part of the study of skeletal remains or corpses in advance decay located in the field involves determining their origin. They may be the result of criminal activity, accident, unearthed because of erosion, or they may also have originated from a cemetery. The discovery site, condition of the remains, and the associated artifacts, are factors that could be helpful for the forensic anthropologist to identify the origin of the remains. In order to contribute to this recognition, an analysis was made of the exhumations of 168 unclaimed human remains from the cemetery of Terrassa (Catalonia, Spain). This investigation presents a description of artifacts and conditions of remains that could indicate that the human remains may have originated from a cemetery.