Estimation Of Postmortem Interval Research Articles

Effect of Insect Exclusion and Microbial Perturbation on Piglet Mass Loss and Total Body Score

Recent conceptual and empirical developments in decomposition research have highlighted the intricate dynamics within necrobiome communities and the roles of various decay drivers. Yet the interactions between these factors and their regulatory mechanisms remain relatively unexplored. A comprehensive understanding of this facet of decomposition science is important, given its broad applicability across ecological and forensic disciplines, and current lack of research which investigates the inter-dependencies between two critical components of the necrobiome (the microbiome and insect activity), and the consequences of this interdependency on mass loss and total body score. Here we investigated the relationships among these key aspects of the decay process. We experimentally manipulated these variables by physically excluding insects and chemically perturbing the external microbiome of piglet (Sus scrofa) carcasses and quantified the effects on mass loss and total body score, as well as insect pre-appearance interval and colonisation. We found that piglets in the insect excluded and microbially perturbed treatment groups exhibited a significant delay in reaching 50+% of mass loss compared with control piglets with insect access and intact microbiome. However, only remains with insects excluded displayed a significantly slower rate of total mass loss throughout the majority of the experiment and remained a significantly higher mass at the endpoint of 11,000 accumulative degree hours. Additionally, all insect excluded and microbially perturbed treatment groups displayed significantly lower total body scores compared to control piglets at corresponding time points. We also observed a significant delay in insect pre-appearance interval and colonisation for piglets with perturbed microbiomes compared to control piglets. Our findings demonstrate the significance of interacting components of the necrobiome, and the power of manipulative experiments in revealing causal relationships between biota and decomposition rates. These considerations are paramount for developing accurate post-mortem interval estimations and a comprehensive understanding of ecological processes during decomposition.

Exploring the impact of xenobiotic drugs on forensic entomology for accurate post-mortem interval estimation

Forensic entomotoxicology is an emerging field within forensic entomology that investigates the effects of chemicals, drugs, and toxins on insect development and their implications for postmortem interval (PMI) estimation. This systematic overview delves into the influence of drugs such as Morphine, heroin, Opiates, and cocaine on the variables affecting the use of forensically significant insects as evidence tools. Notably, it has been observed that the presence of drugs does not appear to alter the progression of the lifecycle from the first instar to the emergence of flies, indicating that PMI estimations based on fly emergence remain unaffected by drugs. However, larvae treated with drugs frequently show delayed pupation, suggesting the need for further research into the impact of different compounds on various insect species over more extended observation periods. Additionally, conflicting results have been noted regarding how toxins can influence the developmental process in larvae, underscoring the necessity to assess the effect of different classes of compounds on other insect species. The study also recommends exploring factors such as the samples’ collection site and the drugs’ pathological implications to inspire future research. Furthermore, the paper underscores the potential for varying drug effects across insect species, emphasizing the complexity of interpreting drug impacts on PMI estimations. This systematic review was conducted by the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines.

Exploring the Post Mortem Interval (PMI) Estimation Model by circRNA circRnf169 in Mouse Liver Tissue

Estimating the post mortem interval (PMI) is a crucial and contentious issue in forensic research, particularly in criminal cases. Traditional methods for PMI estimation are limited by constraints and inaccuracies. Circular RNA (circRNA), formed through exon or intron looping to create a complete circular structure without a 5′ end cap and a 3′ poly(A) tail, exhibits exceptional stability, abundance, and tissue-specific characteristics that make it potentially valuable for PMI estimation. However, research on the exploration or application of circRNA in PMI estimation has been limited. This study aims to investigate the correlation between circRNA and PMI. In this study, liver tissue samples were collected from mice at six different time points at 4 °C, 18 °C, 25 °C, and 35 °C, respectively. The reference gene 28S rRNA and the biomarker circRnf169 were successfully screened. Quantitative PCR was employed to examine the correlation between circRnf169 levels and PMI. At 4 °C, the level of circRnf169 decreased with prolonged PMI, whereas at 18 °C, 25 °C, and 35 °C, the circRnf169 RNA was degraded rapidly, indicating that circRnf169 is suitable for PMI estimation at low temperatures or early PMI. These findings suggest the establishment of mathematical model for early PMI based on circRnf169 using liver tissue, which may serve as a reliable marker. Further research is required in order to develop more markers in mice and/or to validate these mathematical models in human samples.

“Omics” and Postmortem Interval Estimation: A Systematic Review

Postmortem interval (PMI) estimation is a challenge of utmost importance in forensic daily practice. Traditional methods face limitations in accuracy and reliability, particularly for advanced decomposition stages. Recent advances in “omics” sciences, providing a holistic view of postmortem biochemical changes, offer promising avenues for overcoming these challenges. This systematic review aims at investigating the role of mass-spectrometry-based “omics” approaches in PMI estimation to elucidate molecular mechanisms underlying predictable time-dependent biochemical alterations occurring after death. A systematic search was performed, adhering to PRISMA guidelines, through “free-text” protocols in the databases PubMed, SCOPUS and Web of Science. The inclusion criteria were as follows: experimental studies analyzing, as investigated samples, animal or human corpses in toto or in parts and estimating PMI through MS-based untargeted omics approaches, with full texts in the English language. Quality assessment was performed using STROBE and ARRIVE critical appraisal checklists. A total of 1152 papers were screened and 26 included. Seventeen papers adopted a proteomic approach (65.4%), nine focused on metabolomics (34.6%) and two on lipidomics (7.7%). Most papers (57.7%) focused on short PMIs (<7 days), the remaining papers explored medium (7–120 days) (30.77%) and long PMIs (>120 days) (15.4%). Muscle tissue was the most frequently analyzed substrate (34.6% of papers), followed by liver (19.2%), bones (15.4%), cardiac blood and leaking fluids (11.5%), lung, kidney and serum (7.7%), and spleen, vitreous humor and heart (3.8%). Predictable time-dependent degradation patterns of macromolecules in different biological substrates have been discussed, with special attention to molecular insights into postmortem biochemical changes.

Comparative analysis of anticoagulant influence on PMI estimation based on porcine blood metabolomics profile measured using GC-MS.

Accurate post-mortem interval (PMI) estimation is essential in forensic investigations. Although various methods for PMI determination have been developed, only an approximate estimation is still achievable, and an accurate PMI indication is still challenging. Therefore, in this study, we employed gas chromatography-mass spectrometry (GC-MS)-based metabolomics to assess post-mortem changes in porcine blood samples collected with and without the addition of anticoagulant (EDTA). Our study aimed to identify metabolites dependent on the EDTA addition and time (taking into account the biodiversity of the studied organism) and those that are time-dependent but resistant to the addition of an anticoagulant. The experiment was performed on blood samples collected from 16 animals (domestic pig, breed: Polish Large White), 8 with and 8 without EDTA addition. The moment of death (time 0) and 15 additional time points (from 3 to 168 h after death) were selected to examine changes in metabolites' levels in specific time intervals. We employed linear mixed models to study the relationship between metabolite intensities, time and presence of EDTA while accounting for the effect of individual pigs. We confirmed that the intensity of 16 metabolites (mainly amino acids) significantly depends on PMI and the presence of EDTA. However, the intensity of the ideal biomarker(s) for PMI estimation should be determined only by the time after death and not by external factors such as the presence of the anticoagulant agent. Thus, we identified 41 metabolites with time-dependent intensities that were not susceptible to EDTA presence. Finally, we assessed the performance of these metabolites in a PMI predictive model. Citraconic acid yielded one of the lowest errors in general PMI estimation (32.82 h). Moreover, similar errors were observed for samples with and without EDTA (33.32 h and 32.34 h, respectively). Although the small sample size and information leak in predictive modelling prevent drawing definite conclusions, citraconic acid shows potential as a robust PMI estimator.

Analysis of the effect of cypermethrin on the development of Lucilia sericata (Diptera: Calliphoridae)

ABSTRACT Forensic entomotoxicology examines the impact of toxicants on insect development, their presence in carcass-feeding insects, and their bioaccumulation to determine the post-mortem interval (PMI). Incorporate environmental elements to obtain precise estimates of the post-mortem interval. This study examined how cypermethrin affected the fly, Lucilia sericata, throughout various developmental stages. Larvae were grown on pork tissues (liver and muscle) spiked with cypermethrin at various temperatures (20, 25, and 30°C). The study further explored how cypermethrin affected the development rate of L. sericata. The findings revealed that cypermethrin in pork liver and muscle accelerates the growth of Lucilia sericata compared to control samples. This change was constant across all temperature regimes. At 30°C, the average duration from 1st instar to pupae was 172 ± 1.54 hours, at 25°C it was 261.1 ± 1.9 hours, and at 20°C it was 366.2 ± 0.75 hours in pork liver. The average duration from 1st instar to pupae for cypermethrin-treated pork muscle was 169.7 ± 1.45 hours, 261.5 ± 0.65 hours, and 359.7 ± 0.55 hours at 30°C, 25°C, and 20°C, respectively. PMI estimates were impacted by differences in L. sericata larval stage: cypermethrin changed the morphology and the larvae could remain at 30°C for up to 7 hours in pork liver and 4 hours in pork muscle.

Assessing the forensic implications of DNA degradation for PMI estimation using comet assay: A systematic review.

Accurate post-mortem interval estimation is crucial in forensic investigations, providing essential information for criminal cases. Traditional techniques frequently encounter inaccuracies stemming from environmental and individual variables. The comet assay is a very sensitive technique that detects DNA damage, which has emerged as a promising tool for assessing DNA degradation. This approach can serve as a molecular clock for post-mortem interval estimation, offering a more precise and reliable means of determining the time since death in forensic cases. This systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO-CRD42024554907) and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. An extensive electronic database search, including Google Scholar, Embase, Web of Science, PubMed, and Scopus was conducted to find the studies utilizing the comet assay for DNA degradation measurement in post-mortem interval estimation. Two reviewers independently screened and extracted data from eligible studies. The risk of bias tool from the Systematic Review Centre for Laboratory Animal Experimentation was used to evaluate the quality of the research. All six studies fulfilled the inclusion requirements, employing the comet assay on various animal tissues. Studies show a clear relationship between post-mortem interval and degradation of DNA, with varying rates depending on tissue type and environmental factors. The comet assay can detect DNA fragmentation effectively, but difficulties arise from variations in study designs and methodologies. Despite its promise for estimating post-mortem interval, the standardization of protocols is needed to improve reliability and applicability in forensics. Future research should establish standardized methods and explore environmental impacts on DNA degradation.

A preliminary study on estimation of postmortem submersion interval of rat cadavers in freshwater through polyamine analysis in tissues

A preliminary study on estimation of postmortem submersion interval of rat cadavers in freshwater through polyamine analysis in tissues

Comparative soil bacterial metabarcoding after aboveground vs. subsurface decomposition of Mus musculus

Outdoor microcosms, metabarcoding with next-generation sequencing of the 16S rRNA bacterial gene, total body score (TBS) and physicochemical analyses were used to monitor Mus musculus decomposition aboveground (A) and in the subsurface (S), and compared to soil-only controls (C). As determined by MaAsLin2 analysis, significant shifts in bacterial communities at 30 cm depths within the A, S and C treatments distinguished control from experimental soils, and between aboveground and subsurface deposition, demonstrating the potential for gravesoil discrimination during the first 90 days. For example, Dokdonella (p = 0.0002), Edaphobaculum (p = 0.0004) and Lacibacter (p = 0.0034) recorded significant shifts relative to sampling time. Furthermore, Massilia (p = 0.0005), Mycobacterium (p = 0.0006) and Sandaracinus (p = 0.0007) increased in abundance for the aboveground mice treatments. This was confirmed with ANOSIM where p = 0.0082 showed statistically significant difference between the aboveground and subsurface deposition. TBS and physicochemical analyses suggested that nutrient release into the soils occurred during active decay and skin rapture on days 7–13 in the subsurface and days 13–20 aboveground, with a particular increase in soil potassium concentration on day 15. Significant differences in soil temperatures resulted between A and S vs. C microcosms, aligning with atmospheric temperature changes. In summary, complementary application of metabarcoding, total body score, exogenous and physicochemical methods for postmortem interval estimation and clandestine grave location highlighted the feasibility of using temperature records downloaded from meteorological stations and portable X-ray fluorescence as indicators for various phases of decomposition.

Exploring radiomic features of lateral cerebral ventricles in postmortem CT for postmortem interval estimation.

The aim of this study is to investigate the potential of radiomic features extracted from postmortem computed tomography (PMCT) scans of the lateral cerebral ventricles (LCVs) to provide information on the time since death, or postmortem interval (PMI), a critical aspect of forensic medicine. Periodic PMCT scans, referred to as "sequential scans", were obtained from twelve corpses with known times of death, ranging from 5.5 to 273h postmortem. Radiomics features were then extracted from the LCVs, and a mixed-effect model, specifically designed for sequential data, was employed to assess the association between feature values and PMI. Four model variants were fitted to the data to identify the best functional form to explain the relationship between the variables. Significant associations were observed for features, the most significant being the median Hounsfield Units (HU) within the LCVs (p < 9.47 × 10⁻⁹), LCVs surface area (p < 4.69 × 10⁻⁶), L-major axis (p < 2.17 × 10⁻⁵), L-minor axis (p < 1.30 × 10⁻⁴), and HU entropy (p < 4.16 × 10⁻⁴). Our findings align with previous studies, supporting a logarithmic model for PMI-related changes in LCV volume and mean HU intensity value. This study highlights the potential of PMCT-based radiomics as source of complementary information that could be integrated into existing methods for PMI estimation. Our results support the application of a quantitative imaging approach in forensic investigations.

Forensic Entomology in Jeddah: Molecular Identification of Emerging Insect Strains

Background: The precise identification of forensic insects is one of the most important aspects in forensic entomology since it is the basis for determining post-mortem intervals (PMI) and providing other valuable forensic evidence in criminal investigations. Methods: This study demonstrates the utility of DNA barcoding in accurately identifying new strains of forensic insects collected from the Jeddah Governorate. Result: High similarity percentages ranging from 98.74% to 99.68% were observed, underscoring the precision of molecular identification. The identified species included members of the Diptera (flies) and Coleoptera (beetles) orders, commonly associated with forensic cases. Notably, Phoridae sp. (Forensic_JED_21) was identified with 98.74% similarity, highlighting their role in providing valuable post-mortem interval (PMI) estimations. Physiphora alceae was identified twice (Forensic_JED_22 and Forensic_JED_24) with similarities of 99.22% and 99.07%, respectively, demonstrating the robustness of DNA barcoding. Philonthus discoideus (Forensic_JED_23) and Physiphora demandata (Forensic_JED_25) were identified with 99.68% similarity, confirming the presence of these species in the Jeddah region. Phylogenetic analysis using MEGA11 placed these strains in well-defined clades, confirming their taxonomic accuracy and evolutionary relationships. These findings align with previous research on the genetic diversity of forensic insects, adding crucial data to forensic entomology databases. This study enhances the forensic entomology framework by providing accurate species identification, essential for legal investigationsand supports the development of region-specific forensic tools through the addition of new genetic data from Jeddah.

Postmortem interval determination in excised porcine skin using a novel ultrasound-based elasticity measurement device.

Postmortem interval (PMI) estimation, a parameter critical for solving criminal cases, remains a challenge. It has been suggested that elasticity of decomposing tissue may show a relationship to PMI. We measured elasticity of excised porcine skin at regular intervals for 17 days using a novel ultrasound device. Kruskal-Wallis test followed by Dunn's pair-wise comparison test was performed on the elastic modulus values from each time-point. We found statistically significant differences (p < 0.0001) between the elastic modulus values. Pair-wise comparison showed that tissue measured with a PMI of 1-4, 6-9, 10-14, and 16-17 days can be distinguished from each other based on elastic modulus values. An overall trend of increasing elastic modulus values with time was also observed. Histology and H&E staining of skin samples at PMI of 1, 5, 8, and 12 days showed increasingly prominent fibre bundles which may explain the observed trend. The results of our study suggest that estimation of PMI using an ultrasound device is promising and should be explored further.

Field validation of post-mortem interval estimation based on insect development. Part 2: Pre-appearance interval, expert evidence selection and accuracy baseline data

This is the second part of the results from the field experiment aimed at validating PMI estimation based on insect evidence. First, we investigated the accuracy gains of PMI after supplementing age estimates with PAI. Second, we compared the impact on PMI of various ways, in which an expert selects insect evidence for the estimation. Third, we provided baseline data regarding the accuracy of PMI as estimated using different methods, insect species and life stages. Insects were sampled from nine pig carcasses exposed in a forest habitat, one carcass every one or two months, with 8–11 samples taken from each carcass using standard techniques. It was found that insect age alone clearly underestimates the true PMI across insect species and life stages. When age estimates were supplemented with PAI, the estimated PMI became generally significantly closer to the true PMI. Averaging PMI across multiple different pieces of evidence yielded more accurate estimates than using single evidence. The best single evidence method tested in this study, i.e. the use of the oldest evidence from the latest colonizing species, yielded the average PMI errors of about 22 % or 25 % (depending on the type of PAI used). For the best multiple evidence method, i.e. averaging PMI for late life stages of early colonizing species and early life stages of late colonizing species, these errors were about 13 % and 16 %. PMI ranges derived using 30 % error rate covered a true PMI in 95 % of cases but only for the best multiple evidence methods. These results demonstrate that the compound entomological method for estimating PMI (including age and PAI estimates), when applied to mock human death cases, is satisfactorily accurate. Moreover, the present findings highlight the importance of PAI and the great benefits of using multiple insect evidence to estimate PMI.

Detection of miR-133a-5p Using a Molecular Beacon Probe for Investigating Postmortem Intervals.

Background: When a body is discovered at a crime or murder scene, it is crucial to examine the body and estimate its postmortem interval (PMI). Accurate estimation of PMI is vital for identifying suspects and providing clues to resolve the case. MicroRNAs (miRNAs or miRs) are small non-coding RNAs that remain relatively stable in the cell nucleus even after death-related changes occur. Objective: This study developed a molecular beacon probe for mmu-miR-133a-5p and assessed its use in mouse muscle tissue at temperatures of 4 °C and 21 °C to estimate the PMI. Methods: A total of 36 healthy adult male BALB/c mice were divided into 9 PMI time points (0, 2, 6, 8, and 10 days) with 3 mice per time point, and they were exposed to 4 °C and 21 °C. Next, the expression pattern of mmu-miR-133a in the skeletal muscle tissue over a 10-day PMI period was analyzed using the developed molecular beacon probe. Results: The molecular beacon (MB) probe was designed for optimal thermodynamic stability with a hairpin structure that opened in the presence of mmu-miR-133a-5p, thus separating the fluorophore from the quencher and resulting in a strong fluorescence signal at 495 nm. Fluorescence intensity increased with mmu-miR-133a-5p concentration from 1 ng/μL to 1000 ng/μL and exhibited a strong correlation (R2 = 0.9966) and a detection limit of 1 ng/μL. Subsequently, the expression level of mmu-miR-133a-5p was observed to be stable in mouse skeletal muscle tissue at both 4 °C and 21 °C. Conclusions: This user-friendly assay can complete measurements in just 30 min after RNA extraction and is suitable for point-of-care testing, and it possesses the potential to improve existing complex and time-consuming methods for PMI estimation.

The mouse gingiva and HIF-1α, a key gene of hypoxic environment, as tools for post-mortem time estimation.

The post-mortem interval (PMI) is the time elapsed between the death of an individual and its forensic examination. It is a crucial information for judicial authorities, but current techniques still cannot establish a precise time interval. Novel approaches are therefore required. Recently, gingival tissue has emerged as interesting for forensic analysis thanks to the protection offered by lips to this tissue, limiting the influence of environmental factors. It is also easily accessible, and its sampling is minimally invasive even in the presence of rigor mortis. Moreover, the expression of HIF-1α, a master mediator of the hypoxic environment, has been described in gingival samples at different post-mortem (PM) times. We have hypothesized that the time-dependent post-mortem expression of HIF-1α could serve as a biomarker to more accurately predict the PMI. Our analyses were performed in an animal model, the mouse, where environment can be precisely controlled. Therewith, gingival tissue morphology was evaluated through histochemical staining and HIF-1α expression was analyzed by qPCR, western blots and immunofluorescence at different post-mortem times (0h to 100h). Our results showed (a) a global post-mortem stability of gingival tissue (b) a rapid increase in HIF-1α mRNA expression in the short post-mortem times followed by a slow decrease in transcript expression until 100h PM (c) an expression of the HIF- 1α protein and its degradation products, that follows the mRNA pattern (d) the presence of HIF-1α protein in the epithelial and connective layers of the tissue, with signal accumulation in both gingival strata until at least 32h post-mortem. This pilot study thus validated the mouse and the gingival tissue as models for post-mortem analyses, as well as for studying the fate of proteins such as HIF-1α. Transferring these approaches to human subjects may provide a more accurate estimate of PMI.

Raman Handheld Versus Microscopic Spectroscopy for Estimating the Post-Mortem Interval of Human Bones: A Comparative Pilot Study.

The post-mortem interval estimation for human skeletal remains is critical in forensic medicine. This study used Raman spectroscopy, specifically comparing a handheld device to a Raman microscope for PMI estimations. Analyzing 99 autopsy bone samples and 5 archeological samples, the research categorized them into five PMI classes using conventional methods. Key parameters-like ν1PO43- intensity and crystallinity-were measured and analyzed. A principal component analysis effectively distinguished between PMI classes, indicating high classification accuracy for both devices. While both methods proved reliable, the fluorescence interference presented challenges in accurately determining the age of archeological samples. Ultimately, the study highlighted how Raman spectroscopy could enhance PMI estimation accuracy, especially in non-specialized labs, suggesting the potential for improved device optimization in the field.

Altitudinal variations in forensically relevant dipterans in Trentino Region (Italy): implications for PMI estimation and forensic ecology.

This study investigates the populations of dipterans in the southeastern Prealps of Trentino, Italy, along an altitudinal gradient that exceeds 1000m. The study is important because dipterans play a significant role in crime scene analysis by helping to determine the post-mortem interval (PMI) and understand corpse relocation dynamics. Nine aerial traps were used across three sites from May to November 2023, and a total of 17,876 individuals from diverse species were captured. Statistical analyses revealed significant differences in dipteran populations across sites and exposure levels. The study identified relationships between species and environmental factors such as altitude, temperature, and sunlight exposure using Canonical Correspondence Analysis (CCA). Results demonstrated that species composition varied with environmental conditions, offering insights into potential shifts due to climate change. The presence of specific species was notably affected by temperature fluctuations, which could impact their usefulness in PMI estimation. Continuous monitoring is crucial to track dipteran population dynamics amidst changing environmental conditions. Such knowledge is important for improving accuracy in PMI estimations and enhancing forensic investigations. In conclusion, ongoing research is pivotal in adapting forensic entomological analyses to evolving ecological contexts, ensuring their reliability in forensic science applications. This study highlights the dynamic nature of dipteran ecology within forensic contexts and emphasises the need for further investigation to observe shifting population dynamics under climate change impacts.

Influence of Drugs and Toxins on Decomposition Dynamics: Forensic Implications.

Drug and toxin-related deaths are common worldwide, making it essential to detect the postmortem concentration of various toxic substances at different stages of decomposition in a corpse. Indeed, determining the postmortem interval (PMI) and cause of death in an advanced stage of decomposed corpses has been a significant challenge in forensic investigations. Notably, the presence of drugs or toxins can have a significant impact on the microbial profile, potentially altering the succession of microbial communities and subsequent production of volatile organic compounds (VOCs), which, in turn, affect insect colonization patterns. This review aims to highlight the importance of investigating the interactions between drugs or toxins, microbial succession, VOC profiles, and insect behavior, which can provide valuable insights into forensic investigations as well as the ecological consequences of toxins occurring in decomposition. Overall, the detection of drugs and other toxins at different stages of decomposition can yield more precise forensic evidence, thereby enhancing the accuracy of PMI estimation and determination of the cause of death in decomposed remains.

Visual analysis of postmortem interval estimation trends and collaborative networks: a 15-year study (2006-2020).

Utilizing a visual analysis of the literature on postmortem interval (PMI) estimation indexed by Web of Science (WOS), this study investigates developmental trends and research hot points across each 5-year period from 2006 to 2020. Additionally, collaborative efforts among authors, countries, and institutions were examined. Research hot points, high-frequency keywords, authors, countries and institutions in relevant papers were analyzed using CiteSpace.5.7.R2 information visualization analysis software over the past 15 years. The literature related to PMI estimation has witnessed consistent growth over time. In the keyword co-occurrence network, several impactful terms stand out, including blowfly, mitochondrial DNA, and emerging concepts like virtual autopsy. Technological advancements, such as RNA stability analysis and virtual autopsy tools, have played a pivotal role in shaping the direction of PMI research. Scientific research institutions dominate the high-frequency affiliations within the institutional cooperative network. Additionally, the country cooperative network exhibits a trend of co-occurrence and multi-clustering. As science and technology continue to advance, traditional PMI estimation methods mature while novel interdisciplinary approaches drive innovation. By identifying emerging trends and research hotspots, this study provides a roadmap for future investigations, guiding researchers toward new opportunities in PMI estimation.

Multimodal Approaches Based on Microbial Data for Accurate Postmortem Interval Estimation.

Accurate postmortem interval (PMI) estimation is critical for forensic investigations, aiding case classification and providing vital trial evidence. Early postmortem signs, such as body temperature and rigor mortis, are reliable for estimating PMI shortly after death. However, these indicators become less useful as decomposition progresses, making late-stage PMI estimation a significant challenge. Decomposition involves predictable microbial activity, which may serve as an objective criterion for PMI estimation. During decomposition, anaerobic microbes metabolize body tissues, producing gases and organic acids, leading to significant changes in skin and soil microbial communities. These shifts, especially the transition from anaerobic to aerobic microbiomes, can objectively segment decomposition into pre- and post-rupture stages according to rupture point. Microbial communities change markedly after death, with anaerobic bacteria dominating early stages and aerobic bacteria prevalent post-rupture. Different organs exhibit distinct microbial successions, providing valuable PMI insights. Alongside microbial changes, metabolic and volatile organic compound (VOC) profiles also shift, reflecting the body's biochemical environment. Due to insufficient information, unimodal models could not comprehensively reflect the PMI, so a muti-modal model should be used to estimate the PMI. Machine learning (ML) offers promising methods for integrating these multimodal data sources, enabling more accurate PMI predictions. Despite challenges such as data quality and ethical considerations, developing human-specific multimodal databases and exploring microbial-insect interactions can significantly enhance PMI estimation accuracy, advancing forensic science.