Postmortem Interval Research Articles

Integrating Temperature Data with Other Forensic Methods for Time Since Death Estimation

To reliably calculate the time since death is most important for investigating officers in all unnatural deathcases. Reliability of the study can be obtained only when potential influencing factors are considered during the calculation of time since death. One of the methods used for calculating the time since death is based on the cooling of the body. Cooling of the body is influenced by various internal as well as external factors. There are various body temperature-based methods in practice (Henssge’s rectal nomogram, Henssge’s brain nomogram, and Baccino’s both interval and global formulae based on ear temperature) to estimate the post-mortem interval (PMI). The rectum has been traditionally used to determine the central core temperature after death, though the external auditory canal has been proposed as an alternative site. According to published research, techniques based on ear temperature are just as trustworthy as those based on rectal temperature for determining the early PMI and may be employed as rapid, easy, and non-invasive procedures on the scene. It is vital to keep in mind that other aspects such as rigor mortis, lividity, and decomposition must also be taken into account to achieve a more accurate estimate, even if calculating the time since death based on the cooling of the corpse might be informative.Aim: The goal of this study is to thoroughly examine some of the available approaches, compare the accuracy of the results, and determine which method is more accurate (reliable) at estimating the time of death.Methods: It was decided to evaluate some of the earlier research’ published works from different publications and databases. A digital database was searched. Picks were made at random from the studies that were thought to be pertinent to the present goal.Result: Therefore, in addition to the body’s cooling rate, other factors like post-mortem lividity, rigor mortis,chemical changes in the body, and mechanical and electrical excitability of the skeletal muscles, are crucial for a more accurate prediction of the time of death.Conclusion: It is usually advisable to take into account additional factors in addition to the algor mortis-based one when determining the time since death so that a more exact and trustworthy time of death can assist the investigating officer in more precisely resolving medico-legal matters.

Postmortem interval applied to cetacean carcasses: Observations from laboratory and field studies with the Abrolhos Bank Region, Brazil

Estimating the postmortem interval (PMI) in cetaceans is challenging. These mammals often sink after death, later floating and traveling considerable distances before stranding, complicating decomposition stage analysis. Our study investigates decomposition patterns in humpback whale, guiana dolphin, and franciscana dolphin. We analyzed decomposition stages using photographic data from Instituto Baleia Jubarte (IBJ) and conducted a controlled guiana dolphin carcass decomposition study in a laboratory to establish a reliable PMI baseline for carcasses found along Brazil's Abrolhos Bank region. Our findings reveal species-specific decomposition timelines: humpback whale carcasses typically beach within 14 days post-death maximum, while franciscana and guiana dolphins strand within seven to eight days. The most common PMI for whales was five to six days, guiana dolphins four days, and franciscana dolphins four to five days. We used the five decomposition codes: I alive animals, II fresh carcass, III moderate decomposition, IV advanced decomposition, V skeletal remains. For small cetaceans, code II indicates a PMI of two days, III four days, and IV seven days. For large whales, code II signifies a PMI of one day, III three days, and IV seven days. PMI estimation is vital for identifying the period a carcass floated from death site to shoreline. This information supports forensic approaches in understanding anthropogenic impacts on cetacean mortality and aids ecological and conservation studies regarding cetacean strandings, using PMI and backtracking techniques.

Temperature-dependent morphological plasticity in Calliphora vicina: A approach for estimating growth temperature in forensic investigationse

This study investigated the influence of temperature on the life history traits and morphology of the blowfly species Calliphora vicina, drawing on field collections and controlled laboratory conditions. Year-round collection of C. vicina reflected a seasonal trend in the population, with emergence in March, a peak in April, and subsequent decline, followed by a resurgence in September. The sex ratio was skewed towards females, especially during May and June. Development from egg to adult was significantly influenced by rearing temperature, with higher temperatures leading to a shortened developmental duration. Notably, body length and wing size of the adults displayed significant variations across different temperatures, as well as between genders. A strong positive correlation between body length and wing size was evident, suggesting intertwined physiological or genetic mechanisms. Canonical Variate Analysis revealed distinct differences in wing shape among C. vicina reared at different temperatures and wild populations, potentially indicating wing morphology as a temperature-associated marker. Cluster Analysis further showed unique clustering patterns among the wild population and groups reared at 18 °C and 22 °C, with slight gender-based discrepancies. This research results have insightful in the field of forensic entomology, which is estimating the minimum postmortem interval for solving the forensic investigations.

Initial blow fly (Diptera: Calliphoridae) colonization of cats (Felis catus) in Indiana.

Many disciplines are utilized within the field of veterinary forensic sciences, including forensic entomology. Understanding the initial colonization period by flies of forensic importance can contribute to estimating the minimum postmortem interval. There is limited data regarding the time of colonization of animals with fur, and the interpretation of this data is difficult due to the variation in animal models used. The purpose of this study was to examine the initial insect colonization of cats (Felis catus), with light and dark fur. Twelve domestic short-haired cats were placed in cages 15.2 m apart in a grassy field in West Lafayette, IN, United States. Weather data (temperature, precipitation, sun/cloud exposure, humidity), insect activity, time to oviposition, and decomposition changes were documented. Eggs from initial oviposition events were collected and reared to identify the primary colonizing species. Although the time of first oviposition event was not different between the treatments, fur color did affect fly colonization, and cats with dark fur had more oviposition events than cats with light fur (t = 2.639, df = 4, P = 0.029). Three species of Lucilia (Diptera: Calliphoridae) colonized the cats on the initial day of placement. Further studies in cats should include the decompositional studies to understand the unique characteristics that occur during each stage of decomposition, which could aid in developing a scoring system for animals with fur. Additional studies could include analyzing how fur length would affect colonization.

Quetiapine-Related Deaths: In Search of a Surrogate Endpoint.

Quetiapine is a second-generation antipsychotic drug available for two and half decades. Due to increased misuse, prescription outside the approved indications, and availability on the black market, it is being encountered in medicolegal autopsies more frequently. For instance, it has been linked to increased mortality rates, most likely due to its adverse effects on the cardiovascular system. Its pharmacokinetic features and significant postmortem redistribution challenge traditional sampling in forensic toxicology. Therefore, a systematic literature review was performed, inclusive of PubMed, the Web of Science-core collection, and the Scopus databases; articles were screened for the terms "quetiapine", "death", and "autopsy" to reevaluate each matrix used as a surrogate endpoint in the forensic toxicology of quetiapine-related deaths. Ultimately, this review considers the results of five studies that were well presented (more than two matrices, data available for all analyses, for instance). The highest quetiapine concentrations were usually measured in the liver tissue. As interpreted by their authors, the results of the considered studies showed a strong correlation between some matrices, but, unfortunately, the studies presented models with poor goodness of fit. The distribution of quetiapine in distinct body compartments/tissues showed no statistically significant relationship with the length of the postmortem interval. Furthermore, this study did not confirm the anecdotal correlation of peripheral blood concentrations with skeletal muscle concentrations. Otherwise, there was no consistency regarding selecting an endpoint for analysis.

Accurate Prediction of Death Time via Integrating Microbial Community Dynamics

This study addresses the challenge of accurately estimating Postmortem Interval (PMI), the time since death, employing a data-driven approach. PMI determination is crucial in forensic investigations, and traditional methods often lack precision. We focus on utilizing a data mining approach Regularized Random Forest with cross-validation to enhance PMI prediction accuracy. Unlike conventional methods, our approach incorporates external information about the deceased, recognizing the impact of contextual factors on PMI estimation. Recent advancements have seen statistical methods leveraging dynamic changes in microbial communities to predict PMI. However, accuracy has been hindered by various sources of noise. To overcome this limitation, we propose a novel data mining approach, integrating cross-validation techniques and external information to refine PMI predictions. Through an empirical demonstration, we establish that our approach surpasses existing procedures in terms of accuracy, as validated against published datasets. This research contributes to the advancement of PMI estimation methodologies, emphasizing the importance of incorporating comprehensive data mining techniques and contextual information for more precise forensic applications.

Comparative evaluation of macro- and microscopic changes in rabbit, cattle, and pig auricular cartilage following exhumation after different postmortem intervals

The study evaluated and compared macro- and microscopic changes in the auricular cartilage of rabbits, cattle, and pigs following exhumation at different postmortem intervals (PMI). Eight samples corresponding to 0, 5, 10, 15, 20, 25, 30, and 150 days after exhumation were obtained from all rabbit ears, and twelve samples corresponding to 0, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, and 150 days after exhumation were obtained from all cattle and pig ears. The weight loss of the rabbit ear samples remained higher than that of the cattle and pig ear samples at all PMIs. At 60 days, the average weight loss of cattle and pig ear samples did not differ significantly (p>0.05). The loss of area of the samples was similar among the three species at most PMIs (p>0.05). At 150 days, all cattle samples were completely decomposed, unlike the pig and rabbit samples. Microscopic analysis of the cartilage tinctorial affinity and loss of chondrocyte nuclei and tissue architecture demonstrated the worsening of postmortem changes over time, regardless of the animal species. Colonization by fungi and bacteria occurred earlier in the cattle and pig samples. The correlation of time with sample weight loss and cartilage thickness was strong, indicating the potential of these variables as parameters for PMI estimation. Therefore, postmortem examination of auricular cartilage can be used to estimate PMI.

Effect of humidity on postmortem changes in rats.

In veterinary forensic science, accurately determining the postmortem interval (PMI) is crucial for identifying the causes of animal deaths. Autolysis, a significant postmortem process, influences PMI estimation, but its relationship with humidity is not well understood. This study aimed to improve the accuracy of PMI estimates in veterinary forensic cases by looking into how different humidity levels affect autolysis in different organs of rats. The study involved 38 male rats, examining histopathological changes in their heart, liver, and pancreas. These organs were subjected to controlled humidity levels (20%, 55%, and 80%) at a constant 22°C. Tissue samples were collected at several intervals (0 h, 12 h, 24 h, 3 days, and 8 days) for comprehensive analysis. Distinct autolytic characteristics in animal organs emerged under varying humidity conditions. The low-humidity environment rapidly activated autolysis more than the high-humidity environment. In addition, it was found that lower humidity caused nuclear pyknosis, cytoplasmic disintegration, and myofiber interruption. The liver, in particular, showed portal triad aggregation and hepatocyte individuation. The pancreas experienced cell fragmentation and an enlarged intracellular space. High humidity also caused the loss of striations in cardiac tissues, and the liver showed vacuolation. Under these conditions, the pancreas changed eosinophilic secretory granules. The study successfully established a clear connection between the autolytic process in PMIs and relative humidity. These findings are significant for developing a more accurate and predictable method for PMI estimation in the field of veterinary forensic science.

Recovery of Proliferative Fibroblast Cells from Refrigerated Sheep Skin after Different Postmortem Time Intervals and their Characterization

Recovery of Proliferative Fibroblast Cells from Refrigerated Sheep Skin after Different Postmortem Time Intervals and their Characterization

An Evaluation Of Time Since Death From Potassium Level Of Vitreous Humour In The Eyes Of Deceased Brought For Autopsy At Department Of Forensic Medicine Toxicology In A Government Medical College Of Garhwal Region Uttarakhand

Background: The Post-mortem interval is the time between death and the examination of a corpse. It is important to know when the crime was committed. It helps the police to start their investigations with the information available and to process cases more efficiently. Materials and Methods: The sample of vitreous homour was collected from the posterior chamber of both eyes by aspirating gradually and slowly through a puncture 5-6 mm away from the limbus using a sterile 20 gauge needle taking care to avoid tearing of any loose tissue fragments surrounding the vitreous chamber. Results: In the present study there were 80 subjects, out of these subjects maximum subjects were from 26-35 years and minimum were from 66-75 years of age group. Conclusion: In our study, we found that an appreciable pattern of increased potassium concentration in vitreous humour was observed every 12 hours of post-mortem interval, with an approximate 2mmol/l increase.

Unravelling taphono-myths. First large-scale study of histotaphonomic changes and diagenesis in bone from modern surface depositions.

The use of diagenetic alterations in bone microstructure ('histotaphonomy') as indicators of funerary treatment in the past and for post-mortem interval calculations in forensic cases has received increasing attention in the last decade. Studies have used histological changes to conclude in-situ decomposition, mummification, infanticide and post-mortem interval. There has been very little attempt to experimentally validate the links between decomposition, depositional conditions, time-since-death and microscopic changes in human bone so that meaningful interpretations of archaeological and forensic observations can be made. Here, we address this problem experimentally using the largest sample of human remains from anatomical donors and the longest-term deposition framework to date. This study tests one key assumption of histotaphonomy; that putrefaction during the early stages of decay is reflected in bone microanatomy and composition. Seventeen human donors and six pigs were deposited on the surface in a known Australian environment and left to decompose between 463 and 1238 days. All remains underwent all stages of decomposition reaching skeletonisation. Rib and femur samples were analysed using conventional histological methods and scanning electron microscopy, by applying the Oxford Histological Index, and examining collagen birefringence, microcracking and re- and de mineralisation. Biomolecular changes of the femoral samples were analysed using Fourier-transform infrared (FTIR) spectroscopy. The results indicate that bioerosion in human bone does not occur due to putrefaction. There were no correlations between bone histology and the following variables: human vs pigs, season, primary vs secondary deposition, position, fresh vs frozen and time-since-deposition. Furthermore, no trends were observed between biomolecular changes and time-since-deposition. The study also shows that pigs cannot be used as substitutes for human remains for bone biodegradation research. This is the first, controlled, larger scale study of human remains providing a lack of support for a long-assumed relationship between putrefaction and bone histology bioerosion. Using bone degradation as an argument to prove putrefaction, in-situ decomposition and early taphonomic processes cannot be supported based on the experimental human data presented.

Deciphering the microbial signature of death: advances in post-mortem microbial analysis

Cadaver decomposition is a natural phenomenon intimately affected by numerous organisms such as insects, fungi, animals, and bacteria where they use the decaying body as their nutrition source. These organisms can be utilized in forensic science to estimate the post-mortem interval (PMI). The post-mortem interval refers to the time that has passed since the death of a person until the body was found. Forensic entomology is one of the popular approaches where successive colonization of insects on cadaver is studied to estimate PMI. However, sometime this method does not provide consistent results due to lack of insect activities during cold environment conditions or when crime scene is indoor. Therefore, a new approach is needed to aid forensic scientists to estimate PMI. Recently, researchers have noted that microbial communities have shown a predictable and clockwise successional pattern on decomposing cadavers and suggested this could be utilized to estimate PMI when this approach is etched with other established methods. The purpose of this review is to summarize some of the studies that have been conducted on the utility of microbial communities in estimating PMI and discuss the role of microbial communities in cadaver decomposition.

Seasonal mouse cadaver microbial study: rupture time and postmortem interval estimation model construction.

The estimation of postmortem interval (PMI) has long been a focal point in the field of forensic science. Following the death of an organism, microorganisms exhibit a clock-like proliferation pattern during the course of cadaver decomposition, forming the foundation for utilizing microbiology in PMI estimation. The establishment of PMI estimation models based on datasets from different seasons is of great practical significance. In this experiment, we conducted microbiota sequencing and analysis on gravesoil and mouse intestinal contents collected during both the winter and summer seasons and constructed a PMI estimation model using the Random Forest algorithm. The results showed that the MAE of the gut microbiota model in summer was 0.47±0.26 d, R2 = 0.991, and the MAE of the gravesoil model in winter was 1.04 ± 0.22d, R2 = 0.998. We propose that, in practical applications, it is advantageous to selectively build PMI estimation models based on seasonal variations. Additionally, through a combination of morphological observations, gravesoil microbiota sequencing results, and soil physicochemical data, we identified the time of cadaveric rupture for mouse cadavers, occurring at around days 24-27 in winter and days 6-9 in summer. This study not only confirms previous research findings but also introduces novel insights, contributing to the foundational knowledge necessary to advance the utilization of microbiota for PMI estimation.

Extraction and untargeted analysis of metabolome from undemineralised cortical bone matrix.

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) untargeted metabolomics has become the gold standard for the profiling of low-molecular-weight compounds. Recently, this discipline has raised great interest in forensic sciences, especially in the field of toxicology and for post-mortem interval estimation. The current study aims at evaluating three extraction protocols and two LC-MS/MS assays run in both positive and negative modes, to identify the most suitable method to conduct post-mortem metabolomic profiling of bone tissue. A fragment of the anterior tibia of a 82 years-old male sampled from a human taphonomy facility was powdered via freeze-milling. The powdered sub-samples were extracted in five replicates per protocol. Methods tested were (I) a biphasic chloroform-methanol-water protocol, (II) a single phase methanol-water protocol, and (III) a single phase methanol-acetonitrile-water protocol. LC-MS/MS analyses were carried out via high performance liquid chromatography, either on hydrophilic interaction (HILIC) or on reversed-phase (C18) columns in both positive and negative ionisation modes, coupled with a Q-TOF mass spectrometer. Results suggest that the highest consistency between replicates and quality control samples was obtained with the single phase extractions (i.e., methanol-acetonitrile-water), whilst the ideal combination of instrumental set up HILIC chromatography in positive ionisation mode and of C18 chromatography in negative ionisation mode. For the purpose of forensic investigations, a combination of a single phase extraction and the two aforementioned chromatographic and mass spectrometry modes could represent an ideal set up for obtaining bone metabolomic profiles from taphonomically altered bones.

Impact of aluminum phosphide on development of the forensically important fly, Chrysomya albiceps (Diptera: Calliphoridae).

Chrysomya albiceps (Calliphoridae) is among the earliest successional fauna on human and animal cadavers. Some immature Calliphoridae can be useful for determination of post-mortem interval. Toxins, particularly pesticides, can affect the rate of insect growth. Aluminum phosphide (AlP) is an affordable insecticide that has not been adequately entomotoxicologically evaluated. So, the impact of AlP on the developmental rate of different stages of C. albiceps was investigated. Larvae of C. albiceps were reared on the rabbit carcasses containing AlP as a treated group, and distilled water as a control group. The substances were administered by a gastric tube. The duration needed for development of C. albiceps stages was documented. Body length, width and weight of larvae were measured after 24, 48, 72 and 96 h from egg hatching. The duration of development increased significantly in the treated group compared to the control group. Larvae body measurements were significantly smaller in the treated group than in the control group. Therefore, it was demonstrated that AlP significantly influences the size of C. albiceps larvae and extends their development. During forensic application, interpretation of C. albiceps data should be used with caution when aluminum phosphide may be the cause of death.

Thermometrical determination of the postmortem interval by non-linear optimization method

To develop and implement an online application for the numerical method of determination of the postmortem interval and its limiting faults, caused by errors of measurement processes, based on the Marshall-Hoare law of cooling and dual thermometry of the corpse's core. The numerical search for a minimum of two variables' target function, obtained from the system of non-linear Marshall-Hoare equations, reflecting the dual thermometry of the corpse's core was performed. The code of online program was written in Python 3 programming language. The method for determination of the postmortem interval, based on iterative algorithm of non-linear optimization, allowing by dual thermometry of the corpse to consider the uniqueness of its cooling conditions, as well as to calculate the degree of uncertainty of computational estimations, caused by the impact of measurement errors, has been developed. The method is implemented in the format of the Warm Bodies Z online application. The developed numerical method and its online application are recommended for determining of the postmortem interval.

Discrimination of Diptera order insects based on their saturated cuticular hydrocarbon content using a new microextraction procedure and chromatographic analysis.

The nature and proportions of hydrocarbons in the cuticle of insects are characteristic of the species and age. Chemical analysis of cuticular hydrocarbons allows species discrimination, which is of great interest in the forensic field, where insects play a crucial role in estimating the minimum post-mortem interval. The objective of this work was the differentiation of Diptera order insects through their saturated cuticular hydrocarbon compositions (SCHCs). For this, specimens fixed in 70 : 30 ethanol : water, as recommended by the European Association for Forensic Entomology, were submitted to solid-liquid extraction followed by dispersive liquid-liquid microextraction, providing preconcentration factors up to 76 for the SCHCs. The final organic extract was analysed by gas chromatography coupled with flame ionization detection (GC-FID), and GC coupled with mass spectrometry was applied to confirm the identity of the SCHCs. The analysed samples contained linear alkanes with the number of carbon atoms in the C9-C15 and C18-C36 ranges with concentrations between 0.1 and 125 ng g-1. Chrysomya albiceps (in its larval stage) showed the highest number of analytes detected, with 21 compounds, while Lucilia sericata and Calliphora vicina the lowest, with only 3 alkanes. Non-supervised principal component analysis and supervised orthogonal partial least squares discriminant analysis were performed and an optimal model to differentiate specimens according to their species was obtained. In addition, statistically significant differences were observed in the concentrations of certain SCHCs within the same species depending on the stage of development or the growth pattern of the insect.

Use of cadaveric stem cells: analysis of literature

Determination of Post Mortem Interval (PMI) has always been based on empirical analysis of microdata not always endowed with sufficient reliability. Due to its significancy in medico-legal issues, PMI estimation needs to be assessed by applying new and more reliable methods and/or biomarkers. Considering the growing interest and use of stem cells taken from cadaveric tissues and the success in their isolation from death donors, with the maintenance of vitality and regenerative capacity, we evaluated the Literature “state of the art” on this topic to understand if those stem cells could also be used for thanatochrologic estimation. The results obtained from Literature analysis show the possibility of using these cells as a marker for the post-mortal interval. In particular Mesenchymal Stem cells, isolated from adipose and muscular tissues, can be used to evaluate their regenerative capacity over time according to the PMI.

Chrysomya rufifacies: Developmental Analysis Over Range of Temperature

Forensic entomology deals with the study of insects used in criminal investigations. Insects are drawn from the beginning to the decaying carcass and deposit their eggs. Forensic investigators can easily identify the cause of death, the postmortem index, and any changes in the posture of the dead body by observing the insect larval growth and population. Objective: To increase students' interest in pursuing careers related to forensic entomology, this study aims to determine the usefulness and viability of forensic entomology in Pakistan. This also creates an understanding of insects' lifestyles, awareness about beneficial insects, and the development of critical thinking. Forensic entomology plays a role in situations where the body has been dead for a while. Methods: The Maggot Blow Fly (Chrysomya rufifacies) was studied to determine the time since death using insects as evidence. The research at the University of Punjab, Lahore, Pakistan focused on the fly's life cycle and development under different temperature conditions. The aim was to establish the accuracy of using the fly and its life cycle to estimate postmortem interval. Results: The following conditions were observed: temperature (humid) 190˚C–230˚C and cold temperature (dry) 160˚C–220˚C. Room temperature includes Cold Temperature (Humid) at 230˚C -280˚C and Dry at 220˚C - 260˚C. Conclusions: Chrysomya rufifacies employed in this study have shown that the growth cycle is affected by changes in temperature, and these characteristics may be used to predict the minimal period of death.

MicroRNAs molecular biomarkers for determination of drowning death in relation to postmortem interval in different organs of albino rats

MicroRNAs molecular biomarkers for determination of drowning death in relation to postmortem interval in different organs of albino rats