Forensic Taphonomy Research Articles

Estimating the weathering time of the final instar exuviae of Dermestes frischii by ATR-FTIR spectroscopy and GC–MS analysis

Dermestidae is a group of beetles common in forensic and storage research. The weathering patterns of their exuviae may have potential value for the estimation of the postmortem interval (PMI) in forensic entomology, burial time in forensic taphonomy and invasion time in storage containers. However, no relevant research has been done. In this study, a large number of final instar Dermestid exuviae were kept at 16 °C, 25 °C, 34 °C and indoor variable temperatures, allowing them to naturally weather for 90 days. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and gas chromatography-mass spectrometry (GC–MS) were used to detect 13 time points during this period. The corresponding spectra and peak areas of n-alkanes were obtained to explore whether some functional groups or n-alkanes undergo temporal changes in weathering. The results showed that 90 days of weathering did not significantly change the chromatographic peak area or the corresponding spectral absorption peaks of n-alkanes in Dermestid exuviae, while the amides showed an attenuation trend. The accuracy of the training set and test set of the established partial least square-discriminant analysis (PLS-DA) models were 89.04 % and 75.54 %, respectively, and that of the random forest (RF) models were 100 % and 75.00 %, respectively, achieving good classification results. This indicates that the weathering patterns of Dermestid exuviae have value for estimating the PMI. This study is the first to investigate the weathering of necrophagous beetle exuviae with the aim of estimating the PMI. In the future, additional research should be performed under outdoor conditions or a longer weathering time.

Drying the mystery: a novel electronic sensor to quantify soft-tissue desiccation and natural mummification for forensic taphonomy

This study investigates the desiccation process of soft-tissue in South Africa, analyzing its interaction with environmental parameters and its implications for estimating the post-mortem interval. Through the examination of four decomposing porcine bodies across two summer seasons and one winter season, the research quantifies desiccation patterns using custom-designed and constructed printed circuit boards to measure the moisture content of body tissue over time. Generalized additive models were used to determine the environmental forces driving desiccation. Tissue resistivity was tested against the environmental predictor variables to determine the amount of variation they account for, and predicted values of the region-specific tissue resistivity variables were measured for each decomposing body. Results reveal distinct desiccation trajectories between summer and winter, with summer conditions conducive to precocious natural mummification. Environmental factors, particularly temperature and solar radiation, emerge as significant drivers of desiccation. This study represents the first quantitative analysis of deep tissue desiccation internationally, but also the first quantitative assessment of desiccation and natural precocious mummification in the Western Cape, South Africa. The exploration of desiccation as a potential indicator for estimating PMI opens new avenues for research and the integration of innovative methodologies and technologies promises to revolutionize forensic taphonomy practices.

GeoFOR: A collaborative forensic taphonomy database for estimating the postmortem interval

Accurately assessing the postmortem interval (PMI), or the time since death, remains elusive within forensic science research and application. This paper introduces geoFOR, a web-based collaborative application that utilizes ArcGIS and machine learning to deliver improved PMI predictions. The geoFOR application provides a standardized, collaborative forensic taphonomy database that gives practitioners a readily available tool to enter case information that automates the collection of environmental data and delivers a PMI prediction using statistically robust methods. After case submission, the cross-validating machine learning PMI predictive model results in a R² value of 0.82. Contributors receive a predicted PMI with an 80% confidence interval. The geoFOR database currently contains 2529 entries from across the U.S. and includes cases from medicolegal investigations and longitudinal studies from human decomposition facilities. We present the overall findings of the data collected so far and compare results from medicolegal cases and longitudinal studies to highlight previously poorly understood limitations involved in the difficult task of PMI estimation. This novel approach for building a reference dataset of human decomposition is forensically and geographically representative of the realities in which human remains are discovered which allows for continual improvement of PMI estimations as more data is captured. It is our goal that the geoFOR data repository follow the principles of Open Science and be made available to forensic researchers to test, refine, and improve PMI models. Mass collaboration and data sharing can ultimately address enduring issues associated with accurately estimating the PMI within medicolegal death investigations.

Unveiling decomposition dynamics: leveraging 3D models for advanced forensic analysis.

Forensic taphonomy, the study of post-mortem processes, is pivotal in modern forensic science. This short communication illuminates limitations in traditional 2D imaging, specifically digital photographs, within forensic taphonomy, and highlights the vast potential of 3D modeling techniques. Drawing from a recent study in Hawaii's tropical savanna, we unveil disparities between real-time observations and 2D photographs when assessing decomposition, emphasizing the importance of scoring method selection and the need to scrutinize 2D imaging's accuracy in forensic taphonomy. Conversely, 3D modeling techniques, an emerging powerhouse in forensic science, offer multidimensional data, including volume, surface area, and spatial relationships, allowing for comprehensive and precise representation of decomposition dynamics. Despite concerns about texture quality, 3D models yield objective data amenable to analysis by multiple experts, thus minimizing subjectivity and augmenting the reliability of forensic assessments. The potential for 3D modeling to bridge the gap between 2D imaging and real-time decomposition requires tailored methodologies. Future research should focus on standardizing protocols and fostering collaboration among forensic experts, technologists, and researchers to unleash 3D technology's full potential in advancing forensic taphonomy.

Portion size matters: Carrion ecology lessons for medicolegal death investigations-A study in Cape Town, South Africa.

Forensic taphonomic studies are regionally specific and improve time since death estimates for medico-legal casework. Within forensic taphonomy and carrion ecology, vertebrate scavengers are under-researched with many studies conducted using multiple, unclothed carcasses. This is a forensically unrealistic experimental design choice with unknown impact. The effect of variation in carrion biomass on the decomposition ecosystem, particularly where vertebrate scavengers are concerned, requires clarification. To assess the effect of carrion biomass load on vertebrate scavenging and decomposition rate, seasonal baseline data for single, clothed ~60 kg porcine carcasses were compared to clothed multiple-carcass deployments, in a forensically relevant habitat of Cape Town, South Africa. Decomposition was tracked via weight loss and bloat progression and scavenging activity via motion-activated cameras. The single carcasses decayed more quickly, particularly during the cooler, wetter winter, strongly correlated with concentrated Cape gray mongoose (Galerella pulverulenta) scavenging activity. On average and across seasons, the single carcasses lost 68% of their mass by day 32 (567 accumulated degree days [ADD]), compared to 80 days (1477 ADD) for multi-carcass deployments. The single carcasses experienced substantially more scavenging activity, with longer visits by single and multiple mongooses, totaling 53 h on average compared to 20 h for the multi-carcass deployments. These differences in scavenging activity and decay rate demonstrate the impact of carrion biomass load on decomposition for forensic taphonomy research. These findings need corroboration. However, forensic realism requires consideration in taphonomic study design. Longitudinally examining many single carcasses may produce more forensically accurate, locally appropriate, and usable results.

The use of generalized linear mixed models to investigate postmortem lipids in textiles

Human remains are oftentimes located with textile materials, making them a ubiquitous source of physical evidence. Human remains are also frequently discovered in outdoor environments, increasing the exposure to scavenging activity and soft-tissue decomposition. In such cases, postmortem interval (PMI) estimations can be challenging for investigators when attempting to use traditional methods for reconstructive purposes. Lipid analysis is an emerging area of research in forensic taphonomy, with recent works demonstrating success with the detection and monitoring of lipids over time. In this work, generalized linear mixed models (GLMMs) were utilized to perform rigorous statistical analyses on 30 lipid outcomes in combination with accumulated-degree-days (ADD). The results of this study were consistent with recent works, indicating oleic and palmitic acids to be the most suitable lipids in textiles to target for future use as soft-tissue biomarkers of human decomposition. Interspecies differences between humans and pigs were also addressed in this work.

Toxicological Analysis of Drugs in Human Mummified Bodies and Proposed Guidelines.

From palaeopathology to forensic taphonomy, mummified human bodies constitute biological archives of paramount importance. Toxicology analysis of endobiotics and xenobiotics has already shown value to archaeological mummies research with detecting heavy metals, sedative-hypnotic drugs, and stimulants. Thanks to the large window of drug detection in hair and nails, the information from such studies has increased the scientific community's knowledge regarding past populations' lifestyles. Still, few bibliographic references exist regarding toxicology reports in mummified bodies from forensic settings. Here, the authors aim to draw attention to the valuable contribution of toxicology analysis, taking into account previously conducted studies and their findings. Given that sample collection on mummified bodies from forensic scenarios may not always happen in laboratories or autopsy rooms, the authors also suggest guidelines for in situ sampling of forensic mummies. It is expected that the present technical note will encourage experts to perform toxicology analysis in mummified bodies and publish their case reports more often.

Next generation forensic taphonomy: Automation for experimental, field-based research

Determining the post-mortem interval (PMI) is often a critical goal in forensic casework. Consequently, the discipline of forensic taphonomy has involved considerable research efforts towards achieving this goal, with substantial strides made in the past 40 years. Importantly, quantification of decompositional data (and the models derived from them) and standardisation in experimental protocols are being increasingly recognised as key components of this drive. However, despite the discipline’s best efforts, significant challenges remain. Still lacking are standardisation of many core components of experimental design, forensic realism in experimental design, true quantitative measures of the progression of decay, and high-resolution data. Without these critical elements, large-scale, synthesised multi-biogeographically representative datasets – necessary for building comprehensive models of decay to precisely estimate PMI – remain elusive. To address these limitations, we propose the automation of taphonomic data collection. We present the world’s first reported fully automated, remotely operable forensic taphonomic data collection system, inclusive of technical design details. Through laboratory testing and field deployments, the apparatus substantially reduced the cost of actualistic (field-based) forensic taphonomic data collection, improved data resolution, and provided for more forensically realistic experimental deployments and simultaneous multi-biogeographic experiments. We argue that this device represents a quantum leap in experimental methodology in this field, paving the way for the next generation of forensic taphonomic research and, we hope, attainment of the elusive goal of precise estimation of PMI.

Thesis Projects in Forensic Taphonomy

Given the recent growth in the field, some students in forensic anthropology may find it difficult to devise an affordable, suitable, and ideally publishable thesis topic. Taphonomic projects often can fill this role, as many do not require a large budget, are experimental in nature, thus giving students greater control over the data that they will collect, and on topics that have not received large amounts of research. The author presents a list of possible topics primarily in the field of forensic taphonomy and aimed at the MS/MA thesis level, although some proposed projects are larger or could be adapted for a PhD dissertation. The topics include taphonomic effects associated with carnivores, rodents, birds, reptiles, and plants and subaerial weathering; marine environments; thermal alteration; ritual and anatomical activity; cemetery and non-cemetery burials; bone detection; decomposition; and taphonomic procedures. The suggested topics also include factors that may make them more difficult to explore and information on which venues may be the most appropriate. The author hopes to promote taphonomic research in multiple subfields and encourage graduate students to pursue publication of their results.

Informing regional taphonomy research using retrospective forensic anthropology cases in the Western Cape, South Africa

The post-mortem interval (PMI) is important in death investigations as it can assist in reconstructing the context of the case and the identification of the unknown individual. However, in some instances the PMI is challenging to estimate due to the absence of regional taphonomy standards. To conduct accurate and locally relevant forensic taphonomy research, investigators require insight into the regional hotspot recovery areas. Thus, forensic cases examined by the Forensic Anthropology Cape Town (FACT) in the Western Cape (WC) province of South Africa between 2006 and 2018 (n = 172 cases; n = 174 individuals) were retrospectively reviewed. In our study, a considerable number of individuals did not have the PMI estimations (31 %; 54/174) and the ability to estimate a PMI was significantly associated with skeletal completeness, unburnt remains, absence of clothing and the absence of entomological evidence (p < 0.05 for each). Significantly fewer cases had the PMI estimated after FACT was formalised in 2014 (p < 0.0001). One third of cases with PMI estimations were made with large open-ended ranges, making them less informative. Factors significantly associated with these broad PMI ranges were fragmented remains, absence of clothing and absence of entomological evidence (p < 0.05 for each). Most decedents (51 %; 87/174) were discovered in police precincts from high crime areas, yet a considerable number (47 %; 81/174) were also found in low crime and sparsely populated areas regularly used for recreational activities. Common sites of body discovery were vegetated areas (23 %; 40/174), followed by the roadside (15 %; 29/174), aquatic environments (11 %; 20/174) and farms (11 %; 19/174). Decedents were discovered exposed (35 %; 62/174), covered with items such as bedding or shrubs (14 %; 25/174) or buried (10 %; 17/174). Our data highlight gaps in forensic taphonomy studies and clearly informs what regional research is needed. Overall, our study demonstrates how forensic case information can inform regional forensic taphonomy studies to locate common areas and contexts for the discovery of decomposed bodies and encourages similar studies in other areas of the world.

Dehydration-Induced alterations to sharp force trauma on Sus domesticus radii

Dehydration is a taphonomic process that affects nearly all skeletal remains, yet there is a dearth of evidence on this process within the forensic taphonomy literature. When considering the forensic implications of skeletal dehydration, a particular area of concern is sharp force trauma due to its global prominence in forensic cases. In an attempt to address these literature gaps and quantify the effects that dehydration has on skeletal elements, a controlled experiment subjected Sus domesticus (i.e., domestic pig) radii samples (n = 36) to laboratory-induced dehydration after they were inflicted with knife trauma. All samples were photographed pre- and post-dehydration; bone section and kerf mark length, width, and area were then measured from these photographs using ImageJ. Statistical analysis of pre- and post-dehydration samples showed that all measurements experienced significant (p ≤ 0.001) shrinkage, with bone sample area shrinking an average of 8.8 % and kerf mark area an average of 29.7 %. Alterations in length, width and area between the kerf marks and bone samples showed a weak, moderate, and strong correlation, respectively. These findings suggest that anthropological analysis may be affected by dehydration-induced shrinkage, highlighting the necessity of continued research into the effects of dehydration on skeletal trauma.

Estimation of Time Since Death of Bodies Above Soil Surface in A Guinea Forest-Savannah Vegetation of Nigeria Using Visible Post Mortem Changes

Background: Forensic taphonomy is the use of decomposition timeline estimation to unravel mystery behind time of death confirmation in homicide cases involving the law court. The Guinea forest-savannah vegetation is one of the vegetations in Nigeria characterized by short trees, grassland, very hot temperatures almost round the year, speedy wind, etc. It has two distinct seasons – rainy and dry seasons. This study aimed at investigating the visible post mortem changes of domestic pigs (Sus scrofa domestica) in a Guinea forest-savannah vegetation of Nigeria so that it can be used to estimate time since death of bodies on the soil surface. Methods: A stratified random sampling technique was used to select two male and two female matured domestic pigs from a private pig farm located close to the research facility. The visible post mortem changes were observed daily (morning, afternoon and evening) for 49 days. Results: Four stages of decomposition were identified namely fresh, bloat, active decay, and advanced decay stages. Mummification process started at the sixth day post mortem which slowed the rate of decomposition, and prevented the animals to completely skeletonize within the study period. Extreme atmospheric temperature was the major factor that aided the mummification of the animals. Conclusions: Decomposition of domestic pigs in this region accelerates at the early hours of post mortem, and subsequently slows down due to extreme climatic conditions. In addition, it takes carcasses on the soil surface more than 49 days to completely skeletonize due to its vegetative factors. This implies that most crime investigations carried out in this region must take into account the climatic conditions before estimating the time of death. KEYWORDS: Crime investigation, Decomposition timeline estimation, Forensic taphonomy, Mummification, Stages of decomposition, Visible post mortem changes.

Rodent gnawing over fresh, dry and thermo altered bones: an experimental study with archaeological implications at El Mirador Cave (Atapuerca, Spain)

ABSTRACT Rodents gnaw bones to wear down their upper and lower incisors, which grow continuously. These gnawing marks are conspicuous and have long been identified in the fossil record. Archaeological taphonomy studies link modifications made by rodents to weathered and dried bones, while forensic taphonomy indicate that rodents also act on fresh corpses, consuming flesh and other tissues as well as fresh bones. Although these two approaches are complementary, there is a lack of information on how rodents modify bones in states other than dry or fresh. This experimental study aims to fill this gap in the research, describing modifications left by rodents (Mus musculus) to fresh, boiled, carbonised, calcined, and dry bones. Our results indicate that rodents modify bones regardless of their state, and that the most intense gnawing occurs on bones containing fat. During the study, the pedestalling phenomena emerged as a characteristic modification produced only on fresh and boiled samples. We applied our results to the study of the human remains from El Mirador Cave (Atapuerca, Spain) and identified pedestalling for the first time in the archaeological record. This modification may have been favoured by the presence of fatty bones laying exposed on the surface of the site.

Inhumation and cremation: identifying funerary practices and reuse of space through forensic taphonomy at Cova Foradada (Calafell, Spain)

Inhumation and cremation: identifying funerary practices and reuse of space through forensic taphonomy at Cova Foradada (Calafell, Spain)

A retrospective comparative study to evaluate the reliability of post-mortem interval sources in UK and US medico-legal death investigations

Post-mortem interval (PMI) information sources may be subject to varying degrees of reliability that could impact the level of confidence associated with PMI estimations in forensic taphonomy research and in the practice of medico-legal death investigation. This study aimed to assess the reliability of PMI information sources in a retrospective comparative analysis of 1813 cases of decomposition from the Allegheny County Office of the Medical Examiner in Pittsburgh, US (n = 1714), and the Crime Scene Investigation department at Southwest Forensics in the UK (n = 99). PMI information sources were subjected to a two-stage evaluation using an adapted version of the 3x5 aspects of the UK police National Intelligence Model (NIM) to determine the confidence level associated with each source. Normal distribution plots were created to show the distribution frequency of the dependent variables (decomposition stage and source evaluation) by the independent variable of PMI. The manner, location, and season of death were recorded to ascertain if these variables influenced the reliability of the PMI. A confidence matrix was then created to assess the overall reliability and provenance of each PMI information source. Reliable PMI sources (including forensic specialists, missing persons reports, and digital evidence) were used across extensive PMI ranges (1 to 2920 days in the US, and 1 to 240 days in the UK) but conferred a low incidence of use with forensic specialists providing a PMI estimation in only 35% of all homicide cases. Medium confidence PMI sources (e.g., last known social contact) accounted for the majority of UK (54%, n = 54) and US (82%, n = 1413) cases and were associated with shorter PMIs and natural causes of death. Low confidence PMI sources represented the lowest frequencies of UK and US cases and exclusively comprised PMI information from scene evidence. In 96% of all cases, only one PMI source was reported, meaning PMI source corroboration was overall very low (4%). This research has important application for studies using police reports of PMI information to validate PMI estimation models, and in the practice of medico-legal death investigation where it is recommended that i) the identified reliable PMI sources are sought ii) untested or unreliable PMI sources are substantiated with corroborating PMI information, iii) all PMI sources are reported with an associated degree of confidence that encapsulates the uncertainty of the originating source.

Taphonomic model of decomposition

After death human body is subject to the processes of autolysis and putrefaction. Notably, the changes in cadaver during decomposition complicate its forensic analysis and particularly the estimation of the post-mortem interval (PMI). The process and rate of decomposition is impacted by various intrinsic and extrinsic factors that vary across countries and regions. Studying the decomposition pattern in different regions in the world helps us to understand the process and improve the precision of the PMI estimation of decomposed bodies. With the aim to develop a taphonomic model of decomposition in the province of Barcelona (Catalonia, Spain), this study analyses the influence of several intrinsic and extrinsic factors in the pattern and rate of decomposition in this geographical area. Our statistical model concluded that the most significant factors affecting the decomposition pattern and rate are temperature and PMI. Nevertheless, there are other intrinsic factors such as cause, manner of death and underlying pathological conditions which also have an important role. Moreover, considering the various variables studied in this research, two predictive machine learning algorithms were developed as a probabilistic approach to estimate the PMI. Reliable classification results are obtained for three interval groups (1–2 days, 3–10 days, and > 10 days) and two interval groups (>1 week, < 1 week). Machine learning algorithm is a promising tool to gain objectivity in forensic PMI assessments. The results of this study could potentially assist further research in forensic taphonomy.

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.

Can whale-fall studies inform human forensics?

Experimental knowledge of human body decomposition in the deep ocean is very limited, partly due to the logistical challenges of deep-sea research. The literature on ecological responses to the arrival of naturally sunk and implanted whale carcasses on the seafloor represents a potential source of information relevant to questions of human body survival and recovery in the deep ocean. Whale falls trigger the formation of complex, localized, and dense biological communities that have become a point of interest for marine biologists for the past 2-3 decades. Researchers have documented whale falls by whale type, size, geographic location, water depth and water chemistry, and there have been some comparative analyses of decomposition rates and faunal presence on carcasses. We undertook a review and meta-analysis of the whale-fall literature to identify and statistically model trends relevant to human forensics. Results from studies using deep-sea cameras baited with pig carcasses and simulated carrion provided further validation of noted trends. The stages of whale carcass decomposition most relevant to human forensics are those characterised by mobile scavengers that strip the soft tissues from carcasses, and to a lesser degree, other biota that degrade skeletal material. Our statistical models used the number of faunal taxa attracted to the whale carcasses as a measure of the ecological response and the potential rate of decomposition. Negative binomial models identified significant influences of carcass age and dissolved oxygen concentration on the ecological response (taxon numbers). The strongest environmental effects were identified in data from experimental studies that implanted whale carcasses across a broad range of dissolved-oxygen conditions. We propose directions for further experimental research to refine models of environmental controls on decomposition in the deep sea. Our results also highlight the potential use of publicly available global databases on environmental conditions in the deep ocean for informing body scavenging activity and thus body survival. Applying a forensic lens to whale-fall studies provides a window into an otherwise unseen world from the standpoint of human forensic taphonomy.

Can whale-fall studies inform human forensics?

Experimental knowledge of human body decomposition in the deep ocean is very limited, partly due to the logistical challenges of deep-sea research. The literature on ecological responses to the arrival of naturally sunk and implanted whale carcasses on the seafloor represents a potential source of information relevant to questions of human body survival and recovery in the deep ocean. Whale falls trigger the formation of complex, localized, and dense biological communities that have become a point of interest for marine biologists for the past 2–3 decades. Researchers have documented whale falls by whale type, size, geographic location, water depth and water chemistry, and there have been some comparative analyses of decomposition rates and faunal presence on carcasses. We undertook a review and meta-analysis of the whale-fall literature to identify and statistically model trends relevant to human forensics. Results from studies using deep-sea cameras baited with pig carcasses and simulated carrion provided further validation of noted trends. The stages of whale carcass decomposition most relevant to human forensics are those characterised by mobile scavengers that strip the soft tissues from carcasses, and to a lesser degree, other biota that degrade skeletal material. Our statistical models used the number of faunal taxa attracted to the whale carcasses as a measure of the ecological response and the potential rate of decomposition. Negative binomial models identified significant influences of carcass age and dissolved oxygen concentration on the ecological response (taxon numbers). The strongest environmental effects were identified in data from experimental studies that implanted whale carcasses across a broad range of dissolved-oxygen conditions. We propose directions for further experimental research to refine models of environmental controls on decomposition in the deep sea. Our results also highlight the potential use of publicly available global databases on environmental conditions in the deep ocean for informing body scavenging activity and thus body survival. Applying a forensic lens to whale-fall studies provides a window into an otherwise unseen world from the standpoint of human forensic taphonomy.

Outdoor human decomposition in Sweden: A retrospective quantitative study of forensic-taphonomic changes and postmortem interval in terrestrial and aquatic settings.

This paper presents aquantitative retrospective study of gross human decomposition incentral and southeasternSweden. The applicability of methods developed abroad for postmortem interval (PMI) estimation from decomposition morphology and temperature are is evaluated.Ninety-four cases were analyzed(43 terrestrial and 51 aquatic) with amedian PMIof48days. The results revealed differences in decomposition patterns between aquatic, surface, hanging, and buried remains. While partial saponification and desiccation occurred in cases of surface remains, complete skeletonization was observed in all cases with a PMI over two years. Aquatic skeletonization was slower due to extensive saponification in cases with PMI higher than one year. Formulae for assessing accumulated degree-days (ADD) from the original methods didnot fit the study material. However, a regression analysisdemonstratedthat 80% of decomposition variance in surface remains could be explained by ADD, suggesting that a geographically adapted equation holds promise for assessing PMI. In contrast,themodel fit was poor for aquatic cases (43%). While this may be explained by problems in obtaining reliant aquatic temperature data or an insufficient scoring system, aquatic decomposition may be highly dependent on factors other than ADD alone.This study evaluates the applicability of current PMI methods on an outdoor sample from a previously unpublished region, and represents the first scientific publication of human outdoor decomposition patterns in Sweden. Suggestions for future research are provided, including that scoring methods should incorporate saponification to fit forensic taphonomy in Swedish environments.