Estimation Of Postmortem Interval Research Articles

Geographical Distribution and Multimethod Species Identification of Forensically Important Necrophagous Flies on Hainan Island.

Forensic entomology offers unique advantages for the minimum postmortem interval (PMImin) estimation of decomposed corpses in forensic investigations. Accurate species identification and up-to-date locality information are essential. Hainan Island has a tropical rainforest climate and a vast territory. In this study, the community structure of necrophagous flies on Hainan Island was investigated in detail according to geographical environment. The results showed that the dominant species included C. megacephala, S. peregrina, C. rufifacies, S. misera, H. ligurriens, S. sericea, S. cinerea, S. dux, C. pinguis, and M. domestica. Furthermore, C. rufifacies and C. villeneuvi were found only in the high-altitude areas of Wuzhi Mountain, while S. cinerea was distributed only in coastal areas; the latter is a representative species of Hainan Island and has not been reported before. Furthermore, a GenBank database of forensically important flies was established, whilst a high-resolution melt (HRM) curve analysis was applied to identify the common species of Hainan Island for the first time. This study enriches the database of forensically important flies in tropical rainforest regions.

Changes in Microbial Communities Using Pigs as a Model for Postmortem Interval Estimation.

Microbial communities can undergo significant successional changes during decay and decomposition, potentially providing valuable insights for determining the postmortem interval (PMI). The microbiota produce various gases that cause cadaver bloating, and rupture releases nutrient-rich bodily fluids into the environment, altering the soil microbiota around the carcasses. In this study, we aimed to investigate the underlying principles governing the succession of microbial communities during the decomposition of pig carcasses and the soil beneath the carcasses. At early decay, the phylum Firmicutes and Bacteroidota were the most abundant in both the winter and summer pig rectum. However, Proteobacteria became the most abundant in the winter pig rectum in late decay. Using genus as a biomarker to estimate the PMI could get the MAE from 1.375 days to 2.478 days based on the RF model. The abundance of bacterial communities showed a decreasing trend with prolonged decomposition time. There were statistically significant differences in microbial diversity in the two periods (pre-rupture and post-rupture) of the four groups (WPG 0-8Dvs. WPG 16-40D, p < 0.0001; WPS 0-16Dvs. WPS 24-40D, p = 0.003; SPG 0D vs. SPG 8-40D, p = 0.0005; and SPS 0D vs. SPS 8-40D, p = 0.0208). Most of the biomarkers in the pre-rupture period belong to obligate anaerobes. In contrast, the biomarkers in the post-rupture period belong to aerobic bacteria. Furthermore, the genus Vagococcus shows a similar increase trend, whether in winter or summer. Together, these results suggest that microbial succession was predictable and can be developed into a forensic tool for estimating the PMI.

The effects of insect repellent on initial Dipteran colonization of decomposing pig remains.

Numerous factors influence insect colonization and development on decomposing remains and can influence postmortem interval (PMI) estimations when insects are used in investigations of suspicious deaths. This study aimed to determine whether insect repellent influences insect colonization of decomposing remains. Pig feet were divided into 4 groups: a control not sprayed with repellent, 40% DEET repellent, 98% DEET repellent, and lemon eucalyptus repellent. The feet were placed in containers, and insect visitation was observed over the course of 3 days, then insects were collected at the end of the third day. This was repeated twice a month from April through November 2022. The analysis focused on the order Diptera. Pairwise comparison determined that there was a significant delay in visitation time for remains with 98% DEET compared to remains with no repellent and 40% DEET. There were significantly fewer adult Diptera collected and more remains with no larvae or eggs present among remains treated with 98% DEET. It was concluded that low concentrations of DEET and lemon eucalyptus repellent did not delay colonization, but that high concentrations of DEET delayed visitation, reduced the number of adult flies collected from the remains, and reduced the likelihood of collecting eggs or larvae from the remains. This contributes to the understanding of factors that can influence insect colonization and development that allow for more accurate PMI estimations by suggesting that insect repellent does not need to be accounted for in PMI estimation, but a high concentration of DEET can deter insects in the short term.

Recognition of the Presence of Bone Fractures Through Physicochemical Changes in Diagenetic Bone.

Much research has focused on attempting to understand the drivers of bone diagenesis. However, this sensitive process is easily influenced by various factors, particularly the condition of the remains (i.e., whether they have been subjected to trauma). Previous research demonstrates that trauma can influence soft tissue decomposition, yet to date, no studies have looked at how bone fractures could affect bone diagenesis. To address this gap, two short timescale studies were conducted to investigate the influence of bone fractures on the physicochemical composition of disarticulated, partially fleshed animal remains. Disarticulated porcine bones were either fractured using blunt force or sharp force whilst fresh (producing perimortem damage), at 60 days producing postmortem damage (postmortem interval (PMI)), or left intact and left outside for up to 180 days post-fracture/240 days PMI. Retrieved bone sections were then analyzed for physicochemical differences using non-destructive methods, i.e., scanning electron microscopy energy dispersive spectroscopy and Fourier transform infrared spectroscopy with attenuated total reflectance. It was hypothesized that differences would be found in the physicochemical composition between the bones with fractures and those without after undergoing diagenetic change. The bone fractures significantly affected the elemental composition of bone over time, but structural composition initially remained stable. It was also possible to distinguish between perimortem and postmortem fractures using these two analytical techniques due to physicochemical differences. This research shows bone fractures can significantly alter the physicochemical composition of the bone during the postmortem period and have the potential to facilitate more accurate PMI estimations in forensic contexts.

Development of Phormia regina at seven constant temperatures for minimum postmortem interval estimation.

Phormia regina (Meigen, 1826) (Diptera: Calliphoridae) can colonize carcasses quickly, and its immature stages are reliable entomological evidence for the estimation of the minimum postmortem interval (PMImin). There are discrepancies in the developmental data from previous studies on P. regina, and the related PMImin indicators need to be refined. We investigated the accuracy of forensic entomological evidence using development durations, growth accumulated degree hours, and larval body length variations of P. regina at seven constant temperatures ranging from 16 to 34 °C. We also established development models such as the isomorphen diagram, thermal summation model, isomegalen diagram, and body length simulation equation to assist with PMImin estimation. The developmental duration of P. regina from egg to adult at 16, 19, 22, 25, 28, 31, and 34 °C was 840.8 ± 42.8 h, 580.1 ± 10.1 h, 390.4 ± 8.7 h, 316.8 ± 9.4 h, 291.4 ± 21.2 h, 238.4 ± 2.8 h, and 222.5 ± 5.2 h, respectively. The lower threshold temperature TL was 9.97 ± 0.50 °C, while the thermal constant K was 5052.7 ± 229 degree days. The lower developmental thresholds, intrinsic optimum temperature, and upper lethal developmental threshold obtained by the Optim SSI models were 13.15, 21.20, and 36.86 °C, respectively. This study aims to provide developmental models for P. regina aimed at common case-site temperatures in the northern provinces of China, which can be used for accurate PMImin estimation.

The relationship between postmortem interval and protein changes in mice

Postmortem interval (PMI) estimation is important for forensic pathological autopsy. It has been reported that there is a correlation between certain protein changes in cadavers and PMI. However, no specific protein(s) has been used to determine the PMI so far. In this study, the total protein contents of mouse liver and spleen at different time of death were measured. The data showed that they were negatively correlated with the PMI. The degradation of β-actin was found to be positively correlated with the PMI in the liver. Additionally, proteomic technique was used to study the changes of protein expression related to PMI in the liver of mice. By using Two-dimensional electrophoresis, the expressions of four proteins were found to be significantly decreased and those of other three proteins were unchanged with the increase of PMI. Among the seven proteins, six were identified with peptide mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The three altered proteins were SBP2, ENOA, ALDH2 and three unchanged ones were 3HAO, TPIS, CATA, respectively. In the future, those unchanged proteins could be used as internal references to more accurately and reliably infer the time of death by assessing the level of changed proteins.

Evaluating the Time of Death (Post Mortem Interval, PMI) through Forensic Entomo-toxicological Investigations of Maggots and Flies

The estimation of the post mortem interval (PMI) is a critical component of forensic science, aiding investigations and resolving missing persons cases. This abstract explores the innovative approach of forensic entomotoxicological investigations, focusing on the analysis of maggots and flies in PMI estimation. Maggots and flies are key players in the decomposition process, and their lifecycles are closely linked to the stages of decay. Challenges and limitations, such as environmental factors and variable drug metabolism, are considered. Two compelling case studies exemplify the practical applications of forensic entomotoxicology in solving criminal cases and missing persons investigations.&#x0D; The primary goal of this paper is to provide guidance to knowledgeable researchers and investigators in the realm of forensic entomotoxicology. It underscores the need for a heightened focus on forensic Entomotoxicology, particularly in investigations involving the effects of drugs on the growth stages of insect development, for more accurate postmortem interval estimations, especially in cases involving decomposed remains. In conclusion, forensic entomotoxicological investigations of maggots and flies present a dynamic and invaluable approach to PMI estimation, promising to enhance the accuracy and reliability of forensic science in determining the timing of death.

Establishment of a random forest regression model to estimate the age of bloodstains based on temporal colorimetric analysis

Bloodstain age estimation is important in forensic science. Although several studies have used spectroscopy to estimate bloodstain ages, this method has not yet been practically applied due to the need for expensive equipment and low reproducibility. Thus, we aimed to develop a bloodstain age estimation model that can be easily performed using a spectrophotometric colorimeter. First, bloodstains were prepared by placing blood obtained from five healthy volunteers on a plastic plate. The bloodstains were kept on conditions with various brightness and temperatures. Then, each bloodstain was dissolved in saline every 24 h to a final concentration of 1%, measured with a spectrophotometric colorimeter, and subjected to machine learning to generate a random forest regression (RFR) model, and finally, the prediction accuracy of the bloodstain age was verified. We also elucidated the mechanism of the color changes utilizing aminoguanidine, which is an inhibitor of Maillard reaction. Finally, we measured the time-dependent color changes of the blood fluids obtained from healthy volunteers and examined if the method could be potentially applied to estimate postmortem interval (PMI). Our results showed that the RFR model estimated the bloodstain age with no substantial assessment, and it was applicable to bloodstains, regardless of the brightness or temperature. The color changes were affected by the addition of aminoguanidine. Furthermore, the method could be applied to blood fluids, suggesting its potential usefulness for PMI estimation. Considering its feasibility, the present method could potentially be introduced to practical forensic sciences in the near future.

Nomogram based Postmortem-interval estimation compared with the Actual death-interval in Tropical environmental conditions

BackgroundEstimating an accurate postmortem interval (PMI) is essential for death investigators to confirm the offence timing and suspects' alibis. Compared to traditional methods, the Nomogram-based method is claimed to estimate nearly accurate PMI, but most of such studies are based on the Western population. Adequate data for bodies exposed to tropical climate of India and the Indian subcontinent are not available. AimTo assess the accuracy and goodness-of-fit of Nomogram based PMI estimation in bodies exposed to Indian climatic conditions after death. Material and methodsThis is a 3-year-long study on 200 bodies with known death times. The exact PMI was recorded from direct sources: family members, police and hospital records. Before autopsy, the ambient temperature, body weight, length, and rectal temperature were measured, and the details of clothing, sex, and age, were used on a nomogram to calculate the PMI (tN). One-way ANOVA correlation and Mann-Whitney U test were used to compare the variables. Linear regression analysis was used to establish the relationship between the rectal temperature (Tr) and nomogram estimated PMI (tN) and the known PMI(t). The consistency and agreement between the tN and t were measured using Intra-class correlation coefficient (ICC). Bland-Altman (BA) plot was used to compare the level of agreement between direct(t) and nomograms method PMIs. ResultsNomogram-based PMI estimation showed a statistically significant strong relationship with rectal temperature (R 0.77, R2 0.74, adjusted R2 0.76, t-stat 25.83 p < 0.000) and exhibited a relatively consistent agreement with the known death interval (ICC 0.935). Regressing the tN over t showed that the nomogram method can predict PMI with 95 % accuracy. The BA plot between Direct and Nomogram methods exhibited a consistent agreement in PMI estimation though the limits of agreement (LoA) were wide: range 39.09–121.18 min. ConclusionThe accuracy and reliability of the Nomogram method in PMI estimation is high and recommended for the South Indian population. However, the presence of systematic differences between tN and t can't be ruled out due to wider LoA in BA plot. Hence, these findings highlight the need for further investigation and potential refinement of the PMI estimation methods to enhance accuracy and reduce discrepancies.

Necrophagous insect species succession on decomposed pig carcasses in North Dakota, USA.

Necrophagous insect species are widely used during death investigations primarily for the estimation of the minimum postmortem interval, since these species use decomposing organic matter for feeding, oviposition, and larval development. The development stages and successional colonization patterns provide important information for shorter or longer postmortem time intervals. Diptera species are the predominant taxa recovered from decomposed bodies. The temperature variance/seasonality is the main factor affecting the time presence and activity of these species. Other factors, such as geographical location, antemortem conditions, and cause of death, can influence the presence and succession of necrophagous entomofauna. Consequently, successional studies and information regarding species colonization patterns are needed for each geographical region to be used as reference data during death investigations. This study addressed the need to collect forensic entomological data for the State of North Dakota, within the first necrophagous entomofauna diversity report for the month of July 2022, using pig carcasses as human analogs. During the experimental period, 18 species of Diptera and Coleoptera were identified, with 10 new state records, while Calliphoridae was found to be the predominant family. The resulted data on necrophagous insect species diversity and dynamics from exposed pig carcasses will strengthen the current knowledge on forensic entomology in North Dakota and will serve as reference data to be used during death investigations in the Great Plains region.

Multi-omics integration strategy in the post-mortem interval of forensic science

Estimates of post-mortem interval (PMI), which often serve as pivotal evidence in forensic contexts, are fundamentally based on assessments of variability among diverse molecular markers (including proteins and metabolites), their correlations, and their temporal changes in post-mortem organisms. Nevertheless, the present approach to estimating the PMI is not comprehensive and exhibits poor performance. We developed an innovative approach that integrates multi-omics and artificial intelligence, using multimolecular, multimarker, and multidimensional information to accurately describe the intricate biological processes that occur after death, ultimately enabling inference of the PMI. Called the multi-omics stacking model (MOSM), it combines metabolomics, protein microarray electrophoresis, and fourier transform-infrared spectroscopy data. It shows improved prediction accuracy of the PMI, which is urgently needed in the forensic field. It achieved an accuracy of 0.93, generalized area under the receiver operating characteristic curve of 0.98, and minimum mean absolute error of 0.07. The MOSM integration framework not only considers multiple markers but also incorporates machine-learning models with distinct algorithmic principles. The diversity of biological mechanisms and algorithmic models further ensures the generalizability and robustness of PMI estimation.

Objective evaluation of changes in serum transmittance over time using a portable color digitizer

Forensic pathologists empirically understand that postmortem changes can decrease serum transparency and change its color. Such changes are potential indicators for estimating postmortem intervals; however, reports on color changes focusing on postmortem changes in serum are scarce. To elucidate the effect of postmortem intervals on serum levels, we quantitatively evaluated and investigated the relationship between serum color and time using venous blood samples obtained from three healthy male volunteers. The serum samples were separated at 0 (1 h), 1, 2, 3, 4, 7, 10, 16, 21, and 28 days of storage. Serum transmittance and color were measured using a portable color digitizer and a custom-made measurement tool, respectively. Additionally, serum sodium (Na) and potassium (K) concentrations were measured. Serum transmittance showed a logistic curve-like decrease from 0.652 ± 0.016 (0 days) to 0.101 ± 0.014 (28 days) over time. The color changed from greenish yellow (dominant wavelength: 574.4 ± 0.63 nm) to reddish orange (603.97 ± 1.31 nm). Serum Na concentration decreased, whereas serum K concentration increased along the logistic curve. Strong (0.89, p < 0.001) and inverse correlations (−0.93, p < 0.001) were observed between the serum transmittance decrease and the Na concentration decrease and the K concentration increase, respectively. Serum transmittance decreased over time, indicating a transition from bright to dark. Moreover, a strong correlation was observed between serum transmittance and electrolytes, indicating a relationship between time course, serum transmittance, and electrolytes. These findings may contribute to the estimation of postmortem intervals in the future.

Enhancing the Evidence with Algorithms: How Artificial Intelligence Is Transforming Forensic Medicine.

The integration of artificial intelligence (AI) into various fields has ushered in a new era of multidisciplinary progress. Defined as the ability of a system to interpret external data, learn from it, and adapt to specific tasks, AI is poised to revolutionize the world. In forensic medicine and pathology, algorithms play a crucial role in data analysis, pattern recognition, anomaly identification, and decision making. This review explores the diverse applications of AI in forensic medicine, encompassing fields such as forensic identification, ballistics, traumatic injuries, postmortem interval estimation, forensic toxicology, and more. A thorough review of 113 articles revealed a subset of 32 papers directly relevant to the research, covering a wide range of applications. These included forensic identification, ballistics and additional factors of shooting, traumatic injuries, post-mortem interval estimation, forensic toxicology, sexual assaults/rape, crime scene reconstruction, virtual autopsy, and medical act quality evaluation. The studies demonstrated the feasibility and advantages of employing AI technology in various facets of forensic medicine and pathology. The integration of AI in forensic medicine and pathology offers promising prospects for improving accuracy and efficiency in medico-legal practices. From forensic identification to post-mortem interval estimation, AI algorithms have shown the potential to reduce human subjectivity, mitigate errors, and provide cost-effective solutions. While challenges surrounding ethical considerations, data security, and algorithmic correctness persist, continued research and technological advancements hold the key to realizing the full potential of AI in forensic applications. As the field of AI continues to evolve, it is poised to play an increasingly pivotal role in the future of forensic medicine and pathology.

Successional pattern of necrophagous diptera on a dead Asiatic jackal’s (Canis aureus Linnaeus, 1758) body in Veerangana durgawati Wildlife Sanctuary, Madhya Pradesh, India

The field of forensic entomology emphasizes the close relationship between insects and cadavers, as well as the utilization of insects in medicolegal investigations, and helps understand the reasons for death. In forensic science, the presence of necrophagous dipteran flies on a dead body is particularly important as well as they play a significant role in the decomposition of the carcass. In recent times, necrophagous fly data has been used to investigate the causes of mortality. The evidence is useful in the estimation of post-mortem interval (PMI) which is important insolvingmedico-legal cases in human beings, and also helpful in wildlife forensics. The present paper reports day-wise observations of the dipteran visitors on the decaying corpse of the Asiatic Jackal in the Veerangana Durgawati Wildlife Sanctuary, Damoh district, Madhya Pradesh. Adult dipteran flies consisting of five species fewer than four families namely Calliphoridae, Sarcophagidae, Muscidae, and Sepsidae were collected from the site. Chrysomya megacephala was the first visitor of the carcass and both Chrysomya megacephala and Chrysomya rufifacies were the most common species during the various stages of decay of the cadaver. The other necrophagous flies which visited the cadaver were: Musca planiceps, Sarcophaga (Seniorwhitea) princeps, and Themira bifida. This study is the first of its kind conducted in Central India. The findings might be used to supplement the information in forensic investigations for criminal cases and wildlife hunting from India

Expression of human cardiac-specific genes: a novel method for post-mortem interval estimation.

In legal medicine, the determination of post-mortem interval (PMI) is not only an important but also one of the most difficult aspects. Several methods are used to estimate PMI such as physicochemical, entomological, biochemical, metabolic, autolytic, and physical methods. These methods provide a wide range of PMI as they are affected by different factors. The approach behind the present study is to calculate an accurate PMI by using mRNA degradation and fold change expression (FCE) of cardiac-specific genes viz. N-terminal pro-B-type natriuretic peptide (NPPB) and cardiac troponin I (TNNI3). Seventeen cadaver heart tissues were analysed within a time frame of up to 12 hours from the time since death, at different time intervals at room temperature. Gene expression was determined and the data were analysed using the value of average delta Ct (ΔCt) value of the assessed gene and housekeeping gene. Delta delta Ct (ΔΔCt) method was used to calculate the FCE at the different 7-time groups. The FCE of TNNI3 was almost stable till 15 hours of PMI and then after 15 hours, expression shows a decrease up to 24 hours after death; whereas, NPPB shows that FCE was stable till 12 hours of PMI and then after 12 hours, expression shows a decrease up to 24 hours after death. The FCE of NPPB and TNNI3 was almost stable till 12 hours. Thus, the estimation of PMI by analysis of the FCE of cardiac-specific genes can be a new promising method in forensic medicine.

Developmental Indicators of Chrysomya nigripes Aubertin under Different Constant Temperature Conditions and an Application Case for Estimating the PMImin.

Chrysomya nigripes Aubertin, 1932, is a Calliphoridae species that colonize the carcass after the bloat phase and remains for long periods. Some early sarcosaprophagous insects complete one generation of development and are no longer associated with the corpse and surrounding environment, while C. nigripes larvae and pupae remain, providing a basis for the estimation of the minimum postmortem interval (PMImin) for highly decomposed or skeletonized carcasses. However, data on the growth and development of this species are not yet complete. As a result, we studied the developmental patterns of C. nigripes at eight constant temperatures ranging from 16-37 °C and constructed various developmental models, including the isomorphen diagram, isomegalen diagram, linear thermal summation model, nonlinear thermodynamic Optim SSI model, and logistic regression model. Chrysomya nigripes could not complete the entire developmental process at 16 °C, although it could be completed at other temperatures. The mean developmental times (±SD) of C. nigripes from egg to adult at 19 °C, 22 °C, 25 °C, 28 °C, 31 °C, 34 °C, and 37 °C were 644.9 ± 36.8 h, 422.9 ± 20.1 h, 323.1 ± 13.9 h, 246.6 ± 11.2 h, 202.5 ± 1.8 h, 191.5 ± 3.8 h, and 191.8 ± 2.0 h, respectively. The thermal summation constant (K) and lower critical thermal threshold (TL) derived from the linear thermal summation models were 4083.00 ± 293.39 degree hours and 12.52 ± 0.83 °C, respectively. In addition, TL, intrinsic optimum temperature (TΦ), and upper critical thermal threshold (TH) estimated by the optimized nonlinear thermodynamic Optim SSI model were 15.76 °C, 24.88 °C, and 38.15 °C, respectively. This study provides more comprehensive developmental data of C. nigripes for PMImin estimation.

Developmental models and morphological characteristics of the hide beetle, Dermestes frischii, under different constant temperatures

Many species of hide, larder, and carpet beetles (Coleoptera, Dermestidae) are economically important pests of stored products of animal and plant origin, and also have high forensic application value. This study investigated the developmental duration of the immature stage of Dermestes frischii (Kugelann, 1792) under six constant temperatures (19, 22, 25, 28, 31, and 34 °C) and found that development was longest at 19 °C, taking 97.4 ± 7.9 days, and was shortest at 31 °C, taking 31.3 ± 7.2 days. The isomorphen diagram was established based on the developmental events under the different constant temperatures, and the thermobiological parameters of D. frischii were evaluated using linear thermal summation and curvilinear Optim SSI models. The thermal summation constant was 559.89, while the intrinsic optimum temperature and lower and upper lethal developmental thresholds were 24.65, 13.37, and 34.98 °C, respectively. The mortality rate and the mean number of larval instars increased under higher or lower temperatures. The mean instar duration of the first to the fifth instar was generally similar, while the instar duration was the shortest under high temperatures with the fastest developmental rate. We conclude that temperature has a separate effect on the number and duration of the larval instar of D. frischii. In addition, the larval morphological parameters were measured, and the ultrastructures of the antennae, mouthparts, and urogomphi were characterized. This work provides important basic data for storage pest control and minimum postmortem interval estimation of D. frischii in forensic entomology research and application.

Raman spectroscopy for postmortem interval estimation of human skeletal remains: A scoping review.

Estimating postmortem intervals (PMI) is crucial in forensic investigations, providing insights into criminal cases and determining the time of death. PMI estimation relies on expert experience and a combination of thanatological data and environmental factors but is prone to errors. The lack of reliable methods for assessing PMI in bones and soft tissues necessitates a better understanding of bone decomposition. Several research groups have shown promise in PMI estimation in skeletal remains but lack valid data for forensic cases. Current methods are costly, time-consuming, and unreliable for PMIs over 5 years. Raman spectroscopy (RS) can potentially estimate PMI by studying chemical modifications in bones and teeth correlated with burial time. This review summarizes RS applications, highlighting its potential as an innovative, nondestructive, and fast technique for PMI estimation in forensic medicine.

Postmortem skin microbiome signatures associated with human cadavers within the first 12 h at the morgue.

Forensic microbiome studies expanded during the last decade, aiming to identify putative bacterial biomarkers to be used for the postmortem interval (PMI) estimation. Bacterial diversity and dynamics during decomposition are influenced by each individual's micro and macroenvironment, ante and postmortem conditions, varying across body sites and time. The skin, the largest organ of the human body, hosts a diverse microbial diversity, representing the first line of defense of a living individual. Targeting the investigation of the postmortem skin microbiome could help understanding the role of microbes during decomposition, and association with the ante and postmortem conditions. The current study aimed to identify the postmortem skin microbiome signatures associated with eight human bodies, received at the Institute of Legal Medicine Iasi, Romania, during April and May 2021. A total of 162 samples (including triplicate) representing face and hands skin microbiome were investigated via Illumina MiSeq, upon arrival at the morgue (T0) and after 12 hours (T1). The taxonomic characteristics of the skin microbiota varied across different body sites. However, there were no significant differences in taxonomic profiles between collection time, T0 and T1, except for some dynamic changes in the abundance of dominant bacteria. Moreover, different microbial signatures have been associated with a specific cause of death, such as cardiovascular disease, while an elevated blood alcohol level could be associated with a decrease in bacterial richness and diversity. The places where the bodies were discovered seemed to play an important role in explaining the bacterial diversity composition. This study shows promising results towards finding common postmortem bacterial signatures associated with human cadavers within the first 12h at the morgue.

Bridging the gap between decomposition theory and forensic research on postmortem interval.

Knowledge of the decomposition of vertebrate animals has advanced considerably in recent years and revealed complex interactions among biological and environmental factors that affect rates of decay. Yet this complexity remains to be fully incorporated into research or models of the postmortem interval (PMI). We suggest there is both opportunity and a need to use recent advances in decomposition theory to guide forensic research and its applications to understanding the PMI. Here we synthesise knowledge of the biological and environmental factors driving variation in decomposition and the acknowledged limitations among current models of the PMI. To guide improvement in this area, we introduce a conceptual framework that highlights the multiple interdependencies affecting decay rates throughout the decomposition process. Our framework reinforces the need for a multidisciplinary approach to PMI research, and calls for an adaptive research cycle that aims to reduce uncertainty in PMI estimates via experimentation, modelling, and validation.