Postmortem Interval Research Articles

Untargeted and targeted metabolomics analysis of CO poisoning and mechanical asphyxia postmortem interval biomarkers in rat and human plasma by GC[sbnd]MS

Accurate and objective estimation of the postmortem interval (PMI) is crucial in forensic practice. This study aimed to infer PMI through equations based on the relationship between PMI and metabolomics biomarkers.Rats were subjected to models representing various temperatures and causes of death, with blood collected at different intervals. Untargeted gas chromatographymass spectrometry metabolomics detection methods were developed, and candidate biomarkers were chosen as co-differentially expressed metabolites in four models. A targeted method was then developed for quantitatively determining candidate biomarkers. Animal tests and human cadaver samples with clearly documented causes of death and time were used to verify the reliability of the regression equation.Results: Unique differential metabolites for CO poisoning deaths included 2,3-butanediol, hypoxanthine, and dehydrated hexanol, while those for mechanical asphyxia deaths comprised propylamine, 1,3-propylene glycol, phosphoric acid, and sorbitol. Pyruvate, glycerol and isoleucine were identified as candidate biomarkers. Human case results demonstrated the method's potential (error rate < 20 %). The findings of this study may offer reference points for estimating PMI and causes of death in forensic practice.

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.

Molecular identification and genetic variation of forensically important fly species (Order: Diptera) in Thailand using DNA barcoding

Forensic entomology plays a crucial role in criminal investigations by providing vital insights into minimum postmortem interval (PMImin) and corpse relocation by identifying insect species that colonize in decomposing remains. This study aimed to identify and analyze the genetic variation of forensically significant fly species in Thailand, using DNA barcoding of the mitochondrial cytochrome c oxidase subunit I COI gene. A total of 3,220 fly specimens were collected from 18 provinces across six regions of Thailand from October 2017 to September 2022. These specimens were classified by morphological identification into 21 species among three Dipteran families: Calliphoridae, Muscidae, and Sarcophagidae, with Chrysomya megacephala Diptera: Calliphoridae being the most abundant species. DNA barcoding confirmed the morphological identifications with 100 % accuracy, showing low intraspecific K2P distances0.0 to 1.1 %) and significant interspecific K2P distances 2.5 % to 17.2 %. A Neighbour-Joining (NJ) analysis was conducted to assess the molecular identification capabilities of the barcoding region. This analysis successfully recovered nearly all species as distinct monophyletic groups. The species groupings obtained were generally consistent with both morphological and molecular identifications. These findings underscore the effectiveness of DNA barcoding for precise species identification and contribute to a comprehensive database of forensically important flies in Thailand, thus facilitating improved forensic investigations and biodiversity studies.

Examining the Relationship: Porphyromonas gingivalis Presence in Subgingival and Atherosclerotic Plaques of Cadavers

Background: Atherosclerosis and periodontitis are chronic inflammatory diseases characterized by inflammation and tissue destruction. Porphyromonas gingivalis, a key pathogen in periodontal disease, is implicated in initiating inflammation and tissue damage. Objectives: Given the potential link between periodontitis and the development of atherosclerotic plaques, this study aimed to investigate the presence of P. gingivalis DNA in subgingival and atherosclerotic plaques obtained from cadavers at the Tehran Forensic Medicine Center. Methods: In this cross-sectional study, cadavers with a postmortem interval of 6 hours and atherosclerotic plaques in their coronary arteries, along with subgingival plaques exhibiting pocket depths exceeding 5 mm, were examined. Subgingival plaque samples were collected from the deepest sites, while atherosclerotic plaque samples were harvested. Real-time PCR was employed to detect the presence of P. gingivalis in all samples, and the McNemar test was used for data analysis. Results: A total of 25 cadavers were included in the analysis, and both subgingival and atherosclerotic plaque samples were assessed. P. gingivalis DNA was identified in 40% of subgingival plaque samples and 16% of atherosclerotic plaque samples. Moreover, all positive atherosclerotic plaque samples also tested positive for P. gingivalis in the subgingival plaque. McNemar's analysis revealed a statistically significant difference between the subgingival and atherosclerotic samples (P-value = 0.03). Additionally, a correlation coefficient of 0.53 was obtained. Conclusions: While the study has certain limitations, the findings indicate a significant association between the presence of P. gingivalis in subgingival and coronary atherosclerotic plaques. Further investigations are warranted to elucidate the precise role of this periopathogen in atherosclerotic plaque formation.

Survival of Calliphora vicina (Diptera: Calliphoridae) embryos under cold temperature conditions: forensic implications.

Most blow flies (Diptera: Calliphoridae) species are sarcosaprophagous during the larval stage, primarily feeding on the soft tissues of carcasses during the early stages of decomposition, making them valuable forensic indicators for minimum post-mortem interval (minPMI) estimations. Like other insects, their developmental rates are strongly influenced by the environmental temperature. Although several studies have examined the influence of temperature on the development of different blow fly species, the impact of cold temperatures remains largely unstudied, despite its potential forensic implications. The present study investigates the effect of three cold temperatures (0, -2.5 and -5°C) on the survival of Calliphora vicina embryos of five different ages (0%, 20%, 40%, 60% and 80% of the total embryonic development) and two exposure times (6 and 24 h). Our results revealed significant differences in egg survival at the earliest embryonic stages (0% and 20% of the total embryonic development), resulting in high mortality rates. While at 20% of the total embryonic development high mortality was only observed under -5°C, at 0% of the total embryonic development high mortality rates were observed at all the temperatures tested. Although C. vicina embryos demonstrate tolerance to cold temperatures once they have completed the first 20% of the total embryonic development, potentially mitigating the impact of cold weather events, the possibility of minPMI underestimations due to the death of the first egg batches should not be disregarded. Additionally, considering that the embryonic development stages may last for several days under low temperatures, caution should be taken in the analysis of entomological evidence if a cadaver is discovered following cold weather episodes.

Insects on Decomposing Pigs and their Forensic Importance at a University in Nigeria

The use of insects to estimate post-mortem interval (PMI) of cadavers by forensic entomologists, is an innovative science enshrined in the medico-criminal system of the developed world. The science is dependent on the biology of insect species that are found in decomposing cadavers. Thus, insect species that are found on decomposing pigs as model to human cadaver, was studied during the rainy and dry seasons of 2021 in a University forest in Nigeria. The decomposition stages (fresh through skeletonization) of the pig cadavers were monitored, and insects found on them were collected with a sweep net, visually observed, and handpicked. They were identified morphologically using insect identification keys with the aid of a dissecting microscope. The tissues of the pig cadavers decomposed completely in 14 and 10 days, respectively, for dry and rainy seasons. Twenty-seven insect species belonging to the orders; Diptera, Coleoptera, and Hymenoptera were identified. The dipterans consist of the families Calliphoridae, Muscidae, Ulidiidae, and Stratiomyidae. The coleopteran families are the Carabidae, Chrysomelidae, Cleridae, Dermestidae, Histeridae, Scarabaeidae, and Staphylinidae, while Formicidae is the only family for the hymenopteran. The dipteran species were the first group to visit the cadavers during fresh, bloated, and wet decay stages while the coleopterans visited during wet and dry decay stages thus, creating a succession pattern on the cadavers. The insect species that aided the cadaver decomposition at different stages are discussed as forensic indicators, which could be useful as PMI estimators of the study area.

Dental DNA Mutations Occurring after Death: A Novel Method for Post-Mortem Interval (PMI) Estimation.

Post-mortem interval (PMI) estimation remains one of the major challenges in forensic practice, especially for late PMIs beyond 7-10 days after the death of the subject. In 2022, an innovative method to investigate the occurrence of mutations induced by the death of a subject in the DNA of post-mortem dental pulps at different PMIs was developed, applying a next-generation sequencing (NGS) analysis. The present study aims to apply the same method of analysis to a small sample of teeth belonging to the same subject and analyzed at different PMIs/accumulated degree days (ADDs), and of teeth extracted from different subjects but analyzed at the same PMI/ADD to verify the repeatability of the results obtained in relation to the time elapsed since death. A total of 10 teeth were collected from 6 patients (3 males and 3 females) with PMI varying from 8 to 35 days, and ADD from 157.4 to 753.8. We found 1754 mutations in 56 genes, with more than 700 mutations having a prevalence > 5% and more than 300 variants considered of interest for the purposes of the study. Mutations that were not present at lower PMIs but manifested in later PMIs in pulps belonging to the same subject demonstrate that they can only have been acquired by the subject after death and according to the time elapsed since death. In total, 67 somatic mutations in 29 out of the 56 genes of the used panel occurred in a fashion that allows an association with specific PMI/ADD ranges (within 8 days, between 17 and 28, and beyond 30 days after death). The results suggest that temperature and humidity could influence the rate of DNA degeneration in dental pulps, thus PMI should be estimated in ADD more than days. The preliminary validation supports the hypothesis that the innovative method could be a useful tool for estimating the post-mortem interval even beyond the first week after death, but further analyses are needed to customize a specific genetic panel for forensic investigations and verify the influence of degenerative processes of soft tissues surrounding dental elements on DNA degeneration of pulps.

Proteomic Characterization of Changes in Mouse Brain Cortex Protein Expression at Different Post-Mortem Intervals: A Preliminary Study for Forensic Biomarker Identification.

Accuracy in the evaluation of death-induced tissue degradation for thanato-chronological purposes is strictly dependent on the condition of the biological source as well as on the precision of post-mortem interval (PMI) estimation. Thus, the optimization of tissue handling and identification of sensitive post-mortem biomarkers could help establish a timeline for post-mortem events. To this aim, we investigated the proteome changes in cortex samples of 6-week-old female SAMR1 mice over a post-mortem time course. After death, brain tissue was removed immediately (T0), and after 4, 8, 12, 24, and 32 h, four mice were used for each time period, and animals were maintained at 4 °C until brain removal. Dissected tissues were frozen at -80 °C until processed. Proteomic analysis, performed on samples related to early and late PMIs (<24 h and >24 h post-mortem, respectively) showed protein level changes as compared to T0 samples, with a remarkable increase in Calpain11 in the early PMI, as well as in Caspases 7 and 8 together with Gasdermin 3 in late PMI. These findings were confirmed by LIFT mass spectrometry technology and western blot analysis and, although requiring further investigation in other biological samples, suggest that these proteins could be considered as putative biomarkers of different PMIs.

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.

Variations in cuticular hydrocarbons of Calliphora vicina (Diptera: Calliphoridae) empty puparia: Insights for estimating late postmortem intervals.

Necrophagous flies, particularly blowflies, serve as vital indicators in forensic entomology and ecological studies, contributing to minimum postmortem interval estimations and environmental monitoring. The study investigates variations in the predominant cuticular hydrocarbons (CHCs) viz. n-C25, n-C27, n-C28, and n-C29 of empty puparia of Calliphora vicina Robineau-Desvoidy, 1830, (Diptera: Calliphoridae) across diverse environmental conditions, including burial, above-ground and indoor settings, over 90 days. Notable trends include a significant decrease in n-C25 concentrations in buried and above-ground conditions over time, while n-C27 concentrations decline in buried and above-ground conditions but remain stable indoors. Burial conditions show significant declines in n-C27 and n-C29 concentrations over time, indicating environmental influences. Conversely, above-ground conditions exhibit uniform declines in all hydrocarbons. Indoor conditions remain relatively stable, with weak correlations between weathering time and CHC concentrations. Additionally, machine learning techniques, specifically Extreme Gradient Boosting (XGBoost), are employed for age estimation of empty puparia, yielding accurate predictions across different outdoor and indoor conditions. These findings highlight the subtle responses of CHC profiles to environmental stimuli, underscoring the importance of considering environmental factors in forensic entomology and ecological research. The study advances the understanding of insect remnant degradation processes and their forensic implications. Furthermore, integrating machine learning with entomological expertise offers standardized methodologies for age determination, enhancing the reliability of entomological evidence in legal contexts and paving the way for future research and development.

Searching for alternative high DNA-yielding bone types for DNA analysis of aged skeletal remains

The petrous bone contains significantly higher amounts of DNA than any other human bone. Because of highly destructive sampling and because it is not always part of the recovered remains, the need for alternative sources of DNA is important. To identify additional optimal bone types, petrous bones were compared to femurs, tali, and calcanei sampled from 66 adult skeletons from two distinct modern-era Christian cemeteries. An extraction method employing full demineralization was used to obtain DNA, real-time PCR quantification to ascertain DNA quantity and degradation, and a commercial forensic short tandem repeats (STR) PCR amplification kit to determine genetic profiles. Statistical analysis was performed to explore the differences in DNA yield, DNA degradation, and success of STR amplification. A systematic studies exploring intra-skeletal variability in DNA preservation including various excavation sites differing by time period and geographical position are rare, and the second part of the investigation was based on a comparison of both archaeological sites, which allowed us to compare the effect of different post-mortem intervals and environmental conditions on DNA preservation. The older burial site in Črnomelj was active between the 13th and 18th century, whereas the more recent Polje burial was in use from the 16th to 19th century, creating different temporal and geographical environments. Results for the Črnomelj burial site revealed that the petrous bone outperformed all other bone types studied, except the calcaneus. At the Polje archeological site calcanei, tali, and femurs yielded the same STR typing success as petrous bones. The results obtained highlight the importance of careful bone sample selection for DNA analysis of aged skeletal remains. In addition to petrous bones, calcanei were found to be an alternative source of DNA when older burial sites are investigated. When more recent burial sites are processed, calcanei, tali, and femurs should be sampled besides petrous bones, not only because they exhibited good performance, but also because of easier sampling and easier grinding in the case of trabecular bones. This study contributes valuable insights into the potential use of various skeletal types as a source of DNA for investigation of aged skeletal remains, and it offers practical implications for forensic and archaeological investigations.

A methodological approach to age estimation of the intra-puparial period of the forensically relevant blow fly Calliphora vicina via Fourier transform infrared spectroscopy.

Estimating the age of immature blow flies is of great importance for forensic entomology. However, no gold-standard technique for an accurate determination of the intra-puparial age has yet been established. Fourier transform infrared (FTIR) spectroscopy is a method to (bio-)chemically characterise material based on the absorbance of electromagnetic energy by functional groups of molecules. In recent years, it also has become a powerful tool in forensic and life sciences, as it is a fast and cost-effective way to characterise all kinds of material and biological traces. This study is the first to collect developmental reference data on the changes in absorption spectra during the intra-puparial period of the forensically important blow fly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae). Calliphora vicina was reared at constant 20°C and 25°C and specimens were killed every other day throughout their intra-puparial development. In order to investigate which part yields the highest detectable differences in absorption spectra throughout the intra-puparial development, each specimen was divided into two different subsamples: the pupal body and the former cuticle of the third instar, that is, the puparium. Absorption spectra were collected with a FTIR spectrometer coupled to an attenuated total reflection (ATR) unit. Classification accuracies of different wavenumber regions with two machine learning models, i.e., random forests (RF) and support vector machines (SVMs), were tested. The best age predictions for both temperature settings and machine learning models were obtained by using the full spectral range from 3700 to 600 cm-1. While SVMs resulted in better accuracies for C. vicina reared at 20°C, RFs performed almost as good as SVMs for data obtained from 25°C. In terms of sample type, the pupal body gave smoother spectra and usually better classification accuracies than the puparia. This study shows that FTIR spectroscopy is a promising technique in forensic entomology to support the estimation of the minimum post-mortem interval (PMImin), by estimating the age of a given insect specimen.

Ethanol concentrations in various biological specimens: Living and postmortem forensic toxicology analysis and comprehensive literature review

Alcohol use upsurges the risk for many chronic ill-health consequences such as hepatitis, malignancies, and disastrous outcomes like road traffic accidents ending in fatal injuries. Biochemical and toxicological analysis of different body fluids is crucial for identifying the cause of death and postmortem interval in many forensic cases. Blood, urine, and vitreous fluid are the most valuable body fluids for detecting alcohol during any toxicological analysis. Alcohol is responsible for widespread morbidity and mortality worldwide. Blood alcohol concentration (BAC) is a necessary toxicological test to investigate various crime and accident scenes. This study comprehensively explores the demographic characteristics, BAC distribution, and correlations of alcohol concentrations in postmortem and living cases. Postmortem cases (N = 166) reveal intriguing demographic patterns, with notable variations in year distribution, nationality, sex, age groups, occupation, smoking habits, place of death, and psychiatric history. Living cases (N = 483) exhibit distinct demographic profiles, emphasizing differences in year distribution, nationality, sex, age groups, and smoking habits.Analysis of BAC distribution reveals diverse patterns in both postmortem and living cases, providing valuable insights into the prevalence of different BAC levels in each group. Correlation analyses unveil strong associations between alcohol concentrations in various biological samples in postmortem cases, highlighting the interdependence of blood, vitreous, and urine alcohol concentrations. Conversely, living cases display a moderate positive correlation between blood and urine alcohol concentrations.Comparative analyses showcase significant differences in mean alcohol concentrations between postmortem and living cases, suggesting variations in alcohol metabolism and distribution. These findings underscore the importance of considering temporal factors in interpreting alcohol concentrations in forensic and clinical contexts.In conclusion, this study enhances our understanding of alcohol-related incidents by delineating demographic profiles, BAC distributions, and correlations between different biological samples. Such insights are crucial for refining investigative and clinical approaches, contributing to the broader fields of forensic science and public health.

Unidirectional dispersal of blow fly larvae following decomposition fluids from a pig carcass

The decomposition of a body, and the associated gaseous and liquid discharges emanating from it, attract gravid female blow flies which lay their eggs in or on the body. After the eggs have hatched, the emerging larvae start feeding on the body. As decomposition progresses, the blow fly larvae often migrate away, typically in a random manner in search of favourable conditions for pupation. In this paper, we report on a rarely described phenomenon of unidirectional mass migration of blow fly larvae and postulate on the factors which may drive this process. A decomposition trial utilising a 60-kg pig carcass, deployed in the summer months in Table Mountain National Park, Cape Town, South Africa, was conducted in 2022. On the fifth day of the trial, simultaneous unidirectional mass dispersal of blow fly larvae was observed. The larvae moved downhill in a southeasterly direction, following the flow of decomposition fluids oozing out from the pig carcass. The ‘larval migration stream’ had a length of approximately 1.5 m with a width of 40 cm, tapering to 17 cm at the terminal point. The larval migration stream consisted of the larvae of Chrysomya albiceps and Chrysomya chloropyga. This study demonstrates the importance of understanding the timing and pattern of dispersal of post-feeding blow fly larvae in each geographical region. This is crucial as the minimum post-mortem interval can be miscalculated if older immature insects dispersing from the corpse are not considered and collected during crime scene investigations.

Potential Role of mRNA in Estimating Postmortem Interval: A Systematic Review

Although the postmortem interval estimation still represents one of the main goals of forensic medicine, there are still several limitations that weigh on the methods most used for its determination: for this reason, even today, precisely estimating the postmortem interval remains one of the most important challenges in the forensic pathology field. To try to overcome these limitations, in recent years, numerous studies have been conducted on the potential use of the mRNA degradation time for reaching a more precise post mortem interval (PMI) estimation. An evidence-based systematic review of the literature has been conducted to evaluate the state of the art of the knowledge focusing on the potential correlation between mRNA degradation and PMI estimation. The research has been performed using the electronic databases PubMed and Scopus. The analysis conducted made it possible to confirm the potential applicability of mRNA for reaching a more precise PMI estimation. The analysis of the results highlighted the usefulness of some mRNAs, such as β-actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA, especially in short time frames, within a few hours or days of death. The matrices on which these analyses were conducted were also analyzed, resulting in less exposure to the external environment, including the heart, brain, and dental pulp. The major limitations were also reported, including the short time intervals analyzed in most of the articles, the lack of mathematical models, and the failure to report the error rate between the mRNA degradation time and PMI. Given the still small number of published articles, the lack of globally recognized standardized methods, and the numerous techniques used to evaluate the mRNA degradation times, numerous and larger studies are still necessary to reach more solid and shared evidence.

Novel use of a servosphere to study apodous insects: Investigation of blow fly post-feeding larval dispersal.

Blow flies (Diptera: Calliphoridae) are arguably the most important providers of an estimate of minimum post-mortem interval in forensic investigations. They usually undergo a post-feeding dispersal from the body. While previous studies have looked at dispersal of groups of larvae, recording the dispersal activity of individual larvae has not previously been demonstrated. A servosphere was used here to record the speed, directionality and phototaxis of individual post-feeding larvae of two species of blow fly on a smooth plastic surface over time. The servosphere rotates to compensate for the movement of an insect placed at its apex, thereby enabling its unimpeded locomotion in any direction to be studied and behavioural changes to external stimuli recorded. To our knowledge, the servosphere has not previously been used to study apodous insects. The objective of our study was to compare dispersal behaviour of Calliphora vicina Robineau-Desvoidy and Protophormia terraenovae (Robineau-Desvoidy), both common primary colonisers of human and animal cadavers, but showing different post-feeding dispersal strategies. Larvae of C. vicina generally disperse from the body while those of P. terraenovae remain on or close to the body. Our aims were to study (1) changes in dispersal speed over a 1-h period; (2) changes in dispersal speed once a day for 4 days, between the end of feeding and onset of pupariation; and (3) response of dispersing larvae to light. We demonstrated that (1) the movement of three C. vicina larvae tracked for 1 continuous hour on 1 day slowed from an average of 3 to <1.7 mms-1; (2) the average speed of 20 larvae of C. vicina (4.08 mms-1) recorded for 5 min once per day over a 4-day period between onset of dispersal and pupariation was significantly greater than that of P. terraenovae (2.36 mms-1; p < 0.0001), but that speed of both species increased slightly over the 4 days; (3) the responses of larvae of C. vicina to changes in light direction from the four cardinal directions of the compass, showed that they exhibited a strong negative phototactic response within 5 s, turning to move at approximately 180° away from the new light position. While conducted to observe larval calliphorid post-feeding behaviour, the results of this proof of concept study show that apodous insects can be studied on a servosphere to produce both qualitative and quantitative data.

Insect Diversity on Decomposing Domestic Piglets (Sus domesticus ERXLEBEN) Carcasses at Umudike, Southeast Nigeria

Outdoor experiments were carried out to identify arthropods colonizing ground-placed and hung piglets (Sus domesticus) carcasses, their species diversity, and decomposition pattern. The trial was carried out in two seasons: July to September, 2019 (wet), and January to March, 2020 (dry) at Michael Okpara University of Agriculture, Umudike Abia State, Nigeria. A total of four healthy piglets with average weight of 3.73 kg were sacrificed for the trial. The piglets died by dislocating their cervical vertebrate (to mimic natural death); two were placed on the ground in metal cage whereas the other two were hung on a tree. Data on carcasses arthropod populations, temperature, weights and decomposition stages and rates were collected. Results showed that the total arthropod taxa of seventeen genera, ten families in four orders were recorded from the carcasses. A total of 29,629 individual insects were counted, belonging mainly to; Calliphoridae, Muscidae, Sarcophagidae, Dermestidae, Staphylinodea, Pyrrhocoridae and Formidae. Their species abundance was; Musca spp. (37.09 %), Chrysomya spp. (12.97 %), Pheidole spp. (12.09), Componotus spp. (9.69 %), Monomorium spp. (6.04 %), respectively. Higher number of insects were collected from ground-placed piglets (34.08%) than hung piglets (28.06%). More insects were recorded during the dry (55.28%) than wet (44.11%) season. Higher insect diversity was also recorded amongst insect species on ground-placed (0.80) than hung (0.72) carcasses. Data also showed that five stages (fresh, bloat, active decay, advanced decay and skeletonization) of decomposition were observed over a duration of 10 days. This study provided base-line data on the local insect fauna associated with the stages of decomposition with emphases on their arrival time, and it is crucial for estimating the post-mortem interval during forensic investigations in south eastern Nigeria.

Using Stable Nitrogen Isotope Ratios from Human Skeletal Muscle Tissue for Postmortem Interval (PMI) Estimation (Part 1)

Human skeletal muscle tissue was analyzed for stable nitrogen isotope analysis (δ15N) to test the applicability of changes in values (Δ15N) through the putrefaction process for postmortem interval (PMI) estimation. Seasonal differences in Δ15N values of decom-posing skeletal muscle tissue were analyzed from 20 human donors at the University of Tennessee Anthropology Research Facility. This study revealed that change in the δ15N ratios of decomposing muscle tissue has potential as a novel method for PMI estimation. In winter months, when identifiable muscle tissue can be retained on a body for months, the data indicate that there is a systematic increase in Δ15N values with increasing temperatures when putrefaction progresses faster with values shifting as much as 3.0‰. This initial study indicates there is value in further method development of this quantitative approach to PMI estimation for recently deceased individuals, but further work is needed. While the analysis only requires a small amount of tissue, has a user- friendly collection and analysis protocol, and is less subjective than visual methods, there is still significant research to be done prior to widespread applications as a PMI estimation method. Understanding variability in δ15N across decomposing muscle tissue groups, individual variation (i.e., muscle mass, disease, body chem-istry), and an accurate approximation for a perimortem δ15N value necessary to calculate Δ15N all need to be further researched prior to generation of a reliable regression formula and error rates.

Postmortem Immunohistochemical Findings in Early Acute Myocardial Infarction: A Systematic Review.

The diagnosis of early acute myocardial infarction is of particular importance in forensic practice considering the frequency of sudden cardiac death and the difficulty of positively identifying it through classical histological methods if survival is less than 6 h. This article aims to analyze potential immunohistochemical markers that could be useful in diagnosing acute myocardial infarction within the first 6 h of its onset. We conducted an extensive evaluation of the literature according to the PRISMA guidelines for reporting systematic literature reviews. We searched the Web of Science and PubMed databases from their inception to 2023 using the following keywords: "myocardial infarction" and "immunohistochemistry". Fifteen studies met the inclusion criteria. Immunohistochemical markers as complement factors and CD59, myoglobin, fibrinogen, desmin, tumor necrosis factor alpha (TNF-α), P-38, JNK (Jun N Terminal Kinase), transforming growth factor β1 (TGF-β1), cardiac troponins, fibronectin, H-FABP (heart fatty acid binding protein), dityrosine, fibronectin, CD15, IL-1β, IL-6, IL-15, IL-8, MCP-1, ICAM-1, CD18, and tryptase can be used to identify the first six hours of acute myocardial infarction. These markers are mostly studied in experimental animal models. It is necessary to conduct extensive studies on human myocardial tissue fragments, which will involve the analysis of several immunohistochemical markers and careful analysis of the available data on perimortem events, resuscitation, and postmortem intervals in the context of a uniform laboratory methodology.

Development and intrapuparial characterization of Peckia (Euboettcheria) collusor (Curran and Walley, 1934) (Diptera: Sarcophagidae) for application in forensic entomology

The family Sarcophagidae is very diverse in Brazil. Due to their living habits, they are the subject of many medical, veterinary, sanitary, and entomological studies. However, Sarcophagidae species are still poorly studied in forensic entomology, although they are frequently reported in carcasses and even human corpses. Thus, this study aims to identify and compare the developmental stages and intrapuparial morphological characteristics of Peckia (Euboettcheria) collusor to serve as an auxiliary tool in forensic entomology. The pupae collected after zero hour at 27 °C and 32 °C were sacrificed every three hours until the first 24 h and then every six hours until the emergence of the first adults, using 30 pupae each time, totaling 1560 for 27 °C and 1290 for 32 °C. The intrapuparial development time of this fly species under laboratory-controlled conditions was 288 h at 27 °C and 228 h at 32 °C. The 2820 pupae were analyzed according to temperature and classified into eight possible stages. This contributed to the selection of 16 key morphological characteristics to identify the age of the pupae. The identified intrapupal morphological characteristics have great potential to help researchers, experts, technical assistants, and forensic entomologists estimate the minimum post-mortem interval (minPMI) of cadavers.