Catch me if you can-emission patterns of human bodies in relation to postmortem changes.

The present study examines for the first time the emission patterns and olfactory signatures of 9 complete human corpses of different stages of decomposition. Air sampling was performed inside the body bags with solid sorbents and analysed by coupled gas chromatography-mass spectrometry after thermal desorption (TD-GC-MS). Furthermore, odour-related substances were detected by gas chromatography-olfactometry (GC-O). Sulfurous compounds (mainly dimethyl di- and trisulfide) were identified as most important to the odour perception. Around 350 individual organic substances were detected by TD-GC-MS, notably sulfurous and nitrogenous substances as well as branched alkanes, aldehydes, ketones, alcohols, carboxylic acids, carboxylic acid esters and ethers. A range of terpenes was detected for the first time in a characteristic emission pattern over all decomposition stages. Concentrations of the substances varied greatly, and no correlation between the emission patterns, the stage of decomposition and the cause of death could be found. While previous studies often analysed pig cadavers or only parts of human tissue, the present study shows the importance of analysing complete human corpses over a range of decomposition stages. Moreover, it is shown that using body bags as a kind of "emission test chamber" is a very promising approach, also because it is a realistic application considering the usual transport and store of a body before autopsy.

Forensic Proteomics for the Discovery of New post mortem Interval Biomarkers: A Preliminary Study.

Estimating the time since death (post mortem interval, PMI) represents one of the most important tasks in daily forensic casework. For decades, forensic scientists have investigated changes in post mortem body composition, focusing on different physical, chemical, or biological aspects, to discover a reliable method for estimating PMI; nevertheless, all of these attempts remain unsuccessful considering the currently available methodical spectrum characterized by great inaccuracies and limitations. However, recent promising approaches focus on the post mortem decomposition of biomolecules. In particular, significant advances have been made in research on the post mortem degradation of proteins. In the present study, we investigated early post mortem changes (during the first 24 h) in the proteome profile of the pig skeletal muscle looking for new PMI specific biomarkers. By mass spectrometry (MS)-based proteomics, we were able to identify a total of nine potential PMI biomarkers, whose quantity changed constantly and progressively over time, directly or inversely proportional to the advancement of post mortem hours. Our preliminary study underlines the importance of the proteomic approach in the search for a reliable method for PMI determination and highlights the need to characterize a large number of reliable marker proteins useful in forensic practice for PMI estimation.

Factors affecting dental DNA in various real post-mortem conditions.

Post-mortem DNA degradation is still the real challenge of DNA-based identification in forensic practise. It is a complicated multifactorial process occurring as a result of the combination of several different environmental effects along with the crucial effect of the elapsed post-mortem interval (PMI). The main purpose of the present study is to evaluate the effect of ante- and post-mortem factors on dental DNA in real forensic cases. Ninety-five teeth extracted from 39 corpses, whose bodies were subject to 6 different post-mortem conditions, were used to evaluate dental DNA amount. In total, 179 DNA extracts isolated from the root of the teeth were examined after removing the crown and sectioning each root into apical and cervical portions. DNA concentration was measured using real-time polymerase chain reaction DNA quantitation kit (PowerQuant™ System/Promega). Our results indicate that the post-mortem interval (PMI) is the most important influential factor on dental DNA quantification (p < 0.001). However, in the actual data set, it was confounded with several ante- and post-mortem factors, rendering its actual net effect difficult. The time period of the first 10 days after death yielded the best DNA results from all analysed dental samples. Afterwards, a dramatic decrease in dental DNA was observed in the following time period. Teeth extracted from burnt and fresh corpses yielded the highest amount of DNA, while skeletonized exhumed corpses resulted in the lowest DNA amount. Indeed, dry and indoor conditions demonstrated better results than those in water, outdoors, or buried in the ground. On the other hand, ante-mortem factors including sex, age, tooth type, and tooth root portions did not reveal significant effect on dental DNA yield. We suggest that ante-mortem factors are considerably more subjected to individual variations. Post-mortem factors including PMI, post-mortem conditions, and the relevant surrounding environments have substantial influence on the dental DNA amount yielded.

[Molecular genetics and determination of time since death - short communication]. / Molekulární genetika a stanovení doby úmrtí.

Estimation of time since death, i.e. the post-mortem interval (PMI), is one of the most problematic issues in forensic practice. Accurate determination of the PMI still remains very complicated task even for an experienced forensic pathologist.Physical changes including algor, livor and rigor mortis can be observed already during the first hours after death of an individual. Unfortunately, the estimation of PMI on the basis of these changes is often burdened with a certain degree of inaccuracy, which is caused by the temperature of surrounding environment, constitution of the body, cause of the death, location of the body, drug abuse etc.Accurate PMI estimation requires assessment of such parameters, which change constantly from the moment of death, but independently on ambient factors. According to current research in the field of molecular biology, it appears that a post-mortem degradation of nucleic acids (both DNA and RNA) will correspond to this definition.

Morphometric analysis for determination of larval instars in Dermestes frischii Kugelann and Dermestes undulatus Brahm (Coleoptera: Dermestidae).

Dermestes frischii Kugelann, 1792 and Dermestes undulatus Brahm, 1790 are the most abundant species worldwide at outdoor or indoor crime scenes during the dry and skeletal stages of decomposition. The attribution of larval age in these beetles is problematic due to the variable number of instars, which is influenced by environmental factors. In this study, a morphometric approach was used to look for potential morphological features as evidence of larval stages. Breeding and monitoring were performed for both species in an incubator with a preset temperature of 28°C ± 0.5 without a photoperiod. Morphometric measurements were made on 10 larvae per instar for each species using length, width, and thickness parameters. Linear discriminant analysis was then used to generate decision boundaries that clearly separated larval stages. The cross-validation procedure demonstrated that the morphometric approach successfully discriminated adjacent larval stages in both species with high values of sensitivity and specificity. This less-invasive approach could improve the ability to estimate minPMI in forensic studies of Dermestidae beetles. Future studies may extend this approach to other species and establish good practices for collecting and storing specimens for morphometric analysis.

Estimation of Time Since Death From Potassium Levels in Vitreous Humor in Cases of Unnatural Death: A Facility-Based Cross-Sectional Study.

Background Estimation of time since death/postmortem interval (PMI) forms a crucial component for all autopsy surgeons. With the subjectivity that is prevalent with conventional morphological and physical signs of death, newer-age modalities such as chemical analysis provide better precision. The easy accessibility and the resistance to putrefaction make vitreous humor the best choice for such chemical analysis. Thus, the present study's aim is to estimate the time since death in cases of unnatural death by investigating the potassium level changes in the vitreous humor. Methodology This is a facility-based cross-sectional study conducted in the mortuary under the Department of Forensic Medicine in a public tertiary healthcare teaching hospital in South India between August and September 2022. Deceased individuals fulfilling the inclusion and exclusion criteria were recruited in the study. Vitreous samples were collected from a single eye and analyzed using an autoanalyzer for potassium values. After due derivations, postmortem intervals were calculated from potassium values, then they were compared with the PMIs estimated using physical signs and those determined using official police records. Data were entered using MS Excel 20 (Microsoft Corporation, Redmond, Washington) and analyzed using the Statistical Package for the Social Sciences (SPSS) software, version 20 (IBM Corp., Armonk, NY). Results Of the 100 deceased individuals included in the study, 68% were men, and the majority (24%) belonged to the age group of 53-62 years. A linear relationship is said to exist between vitreous potassium concentration and postmortem interval. No correlation was seen between the ambient temperature and the potassium levels of the vitreous humor. PMI confirmed by the potassium levels seconded the PMI given by the police records and physical signs (Rigor mortis) (Spearman's rho was statistically significant at the two-tailed level or at the 0.01 level with a kappa value of 0.88). Conclusion Potassium measurements in the vitreous humor to estimate the PMI are associated with improved accuracy and precision in determining the time since death. They are not affected by external factors, making them a reliable marker for the same.

Post-mortem interval estimation using miRNAs of road traffic accident cases: A forensic molecular approach.

In forensic examination accurate estimation of post-mortem interval (PMI) is a challenging task, particularly in the advanced stages of decomposition. The existing methods (algor mortis, livor mortis, rigor mortis, putrefaction etc) used for estimating PMI rely on analyzing the physical, biochemical, and metabolic changes that occur in the corpse after death. While these methods have shown some level of effectiveness in estimating PMI during the early stages of decomposition, accurate estimation becomes increasingly challenging during the later stages of putrefaction when the body undergoes significant changes. Recently, microRNA (miRNA) profiling due to its relatively small size and stability has emerged as a promising tool in several areas of forensics. This study demonstrates the potential of miRNA for PMI estimation in advanced stages of death. In this study, miRNA-195, miRNA-206, and miRNA-378 were selected as target miRNAs and miRNA-1 as reference miRNA. Left ventricle tissue (5 g) of the heart from 20 forensic autopsies of traffic accident victims (18-32 years) were collected and processed. The samples were held at room temperature for eight different time intervals (12, 24, 48, 72, 96, 120, 168 and 196 h), and RNA was extracted from all the samples using Trizol-based RNA isolation protocol, followed by cDNA synthesis and amplification with commercially available specific miRNA probes in Real-Time PCR (RT-PCR), Ct was calculated. The result showed that miRNAs were associated with PMI. Over time, there were substantial changes in the Ct values of all three miRNAs, with significant reductions observed at 196 h compared to 12 h. miRNA-206 demonstrated significant changes at multiple time intervals, while miRNA-1 remained stable for up to 196 h and thus holds caas an endogenous marker. In conclusion, miRNA has the potential to serve as a valuable tool for estimating PMI, especially during the advanced stages of decomposition, when used in conjunction with established techniques. However, further validation of the study is required to obtain more accurate estimates of PMI.

Taphonomic model of decomposition.

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

Predictive equation to estimate post-mortem interval using spectrophotometric blood-colour values.

Forensic pathologists use post-mortem phenomena to estimate the post-mortem interval (PMI). We have reported on the usefulness of post-mortem lividity spectrophotometric values to estimate PMIs. Here, we focused on blood colour, looking for associations between blood colour, age and PMI. We generated predictive equations for blood-colour values and the PMI. We included data from a total of 129 cadavers (84 males and 45 females). We measured the colour of 124 left ventricular blood ( L*l, a*l, b*l), 123 right ventricular blood ( L*r, a*r, b*r) and 57 femoral blood ( L*f, a*f, b*f) samples. We found no significant associations between blood colour and age or between blood colour and the PMI, but the values of a*l, b*l, a*r and b*r were significantly increased with increased age, and those of L*f, a*f and b*f were significantly decreased with increased PMI. We created equations to estimate blood colour. The equations for femoral blood colour had higher adjusted R2 values and lower root mean square error values than those for left and right ventricular blood colours. We generated equations to estimate PMIs using blood-colour values and autopsy findings. Our estimated PMIs up to 67 hours had accuracies within 8.84 hours, without measuring post-mortem lividity colour or considering the age of the deceased. This is the first study to estimate PMIs based on blood-colour spectrophotometric values.

Analysis of hypoxanthine and lactic acid levels in vitreous humor for the estimation of post-mortem interval (PMI) using LC-MS/MS.

Hypoxanthine (Hx) is produced during terminal stages of purine catabolism in humans. The concentrations of Hx and l-lactic acid in vitreous humor highly correlate with post-mortem interval (PMI). In this study, we measured the concentrations of Hx and l-lactic acid in uncontrolled authentic vitreous humor from cadavers, and investigated the correlation between these molecules and PMI. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for the quantitative analysis of Hx and l-lactic acid in vitreous humor. These concentrations were also corrected by four seasons such as spring, summer, autumn, and winter and temperatures on the day of death such as -10 to 5 °C, 6-15 °C, 16-25 °C, and 26-32 °C that may affect the biomarker concentrations. Vitreous humors were collected from cadavers with known time of death at the National Forensic Service (NFS), Republic of Korea. The correlation between the concentrations of Hx and l-lactic acid in vitreous humors and PMI was evaluated using 79 corpses (53 males and 26 females), with sampling time ranging from 13 to 103 h after death. The average daily ambient temperature at the time of death of each sample was investigated to calibrate the correlation with PMI. Following correction of the concentrations of Hx and l-lactic acid with temperature, the correlation of Hx and l-lactic acid with PMI increased from 0.53 to 0.59 for Hx and 0.38 to 0.42 for l-lactic acid. The highest correlation of Hx and l-lactic acid concentrations with PMI was observed in the winter season, with an R2 value of 0.80 and 0.71 for Hx and l-lactic acid, respectively. The correlation of Hx and l-lactic acid with PMI was corrected by ambient temperature for each season, resulting in an increase in the R2 value to 0.88 for Hx and 0.72 for l-lactic acid. The best correlation was observed when the temperature was corrected after dividing by season.

Eye temperature measured after death in human bodies as an alternative method of time of death estimation in the early post mortem period. A successive study on new series of cases with exactly known time of death.

The paper presents a continuation of the studies on time of death (TOD) estimation based on post-mortem temperature measurements in the human eyeball. In the current study, single (in 20 patients) or double (within a 1-hour interval in 10 patients) eyeball and rectal temperature measurements were taken in patients who died in the University Hospital Intensive Therapy Unit. The actual TOD in each patient was exactly known and the body temperature was recorded shortly after (between 50 min and 3 h 30 min). The temperature was measured using pin probes connected to a high precision electronic thermometer. The measured eye temperatures ranged from 27.4 to 33.7°C. The ambient temperature in all cases was stable (22 °C), which corresponded to the usual room temperature. Post mortem interval (PMI) was calculated using a formula based on Newton's law of cooling, previously successfully applied in comprehensive studies on pigs and recent studies on human bodies. Thanks to knowledge of the exact TOD and the stable ambient temperature, the current study on 30 new cases allowed the method to be improved by adjusting the mean value of the cooling constant and the initial eye temperature in comparison to recent studies.

The importance of Saprinus semistriatus (Coleoptera: Histeridae) for estimating the minimum post-mortem interval.

In forensic science, the use of entomological evidence to estimate the minimum post-mortem interval can be crucial. However, not all cadaver-visiting insects are equally useful. Our focus is on the histerid beetle Saprinus semistriatus (Scriba 1790) (Histeridae; Coleoptera). Histeridae are common predators that feed mainly on dipteran larvae on carrion and dung. We review 23 publications mentioning this species and provide new experimental data on its temporal pattern beneath and on hanging pig cadavers. In a field experiment near Neuchâtel, Switzerland, we recorded the abundance of S. semistriatus on ten decomposing pig cadavers (Sus scrofa) over a 32-day period in summer 2013 (July, 01- August; 02). Five cadavers were placed on the ground and five cadavers were hung one metre above the ground. Insects were collected from pitfall traps and by manual sampling. The abundance of S. semistriatus was significantly higher during the active stage than during the fresh and the bloated stages of decomposition in both, ground and hanging pigs. However, S. semistriatus was more abundant on the ground than on the hanging cadavers. The literature and our new data show that S. semistriatus is present on cadavers during a relatively short period of time (approximately two weeks), mainly during the active decay stage, but it may also occasionally occur in the bloated stage. Identifying key indicators such as S. semistriatus can help optimise forensic research by focusing on the most informative taxa. A few key indicators for each decomposition stage may constitute an optimal toolbox for forensic entomologists.

Present and foreseeable future of metabolomics in forensic analysis.

The revulsive publications during the last years on the precariousness of forensic sciences worldwide have promoted the move of major steps towards improvement of this science. One of the steps (viz. a higher involvement of metabolomics in the new era of forensic analysis) deserves to be discussed under different angles. Thus, the characteristics of metabolomics that make it a useful tool in forensic analysis, the aspects in which this omics is so far implicit, but not mentioned in forensic analyses, and how typical forensic parameters such as the post-mortem interval or fingerprints take benefits from metabolomics are critically discussed in this review. The way in which the metabolomics-forensic binomial succeeds when either conventional or less frequent samples are used is highlighted here. Finally, the pillars that should support future developments involving metabolomics and forensic analysis, and the research required for a fruitful in-depth involvement of metabolomics in forensic analysis are critically discussed.

Application of soil in forensic science: residual odor and HRD dogs.

Decomposing human remains alter the environment through deposition of various compounds comprised of a variety of chemical constituents. Human remains detection (HRD) dogs are trained to indicate the odor of human remains. Residual odor from previously decomposing human remains may remain in the soil and on surfaces long after the remains are gone. This study examined the ability of eight nationally certified HRD dogs (four dual purpose and four single purpose) to detect human remains odor in soil from under decomposing human remains as well as soils which no longer contained human remains, soils which had been cold water extracted and even the extraction fluid itself. The HRD dogs were able to detect the odor of human remains successfully above the level of chance for each soil ranging between 75% and 100% accurate up to 667 days post body removal from soil surface. No significant performance accuracy was found between the dual and single purpose dogs. This finding indicates that even though there may not be anything visually observable to the human eye, residual odor of human remains in soil can be very recalcitrant and therefore detectible by properly trained and credentialed HRD dogs. Further research is warranted to determine the parameters of the HRD dogs capabilities and in determining exactly what they are smelling.

Studies on time of death estimation in the early post mortem period -- application of a method based on eyeball temperature measurement to human bodies.

This paper presents a verification of the thermodynamic model allowing an estimation of the time of death (TOD) by calculating the post mortem interval (PMI) based on a single eyeball temperature measurement at the death scene. The study was performed on 30 cases with known PMI, ranging from 1h 35min to 5h 15min, using pin probes connected to a high precision electronic thermometer (Dostmann-electronic). The measured eye temperatures ranged from 20.2 to 33.1°C. Rectal temperature was measured at the same time and ranged from 32.8 to 37.4°C. Ambient temperatures which ranged from -1 to 24°C, environmental conditions (still air to light wind) and the amount of hair on the head were also recorded every time. PMI was calculated using a formula based on Newton's law of cooling, previously derived and successfully tested in comprehensive studies on pigs and a few human cases. Thanks to both the significantly faster post mortem decrease of eye temperature and a residual or nonexistent plateau effect in the eye, as well as practically no influence of body mass, TOD in the human death cases could be estimated with good accuracy. The highest TOD estimation error during the post mortem intervals up to around 5h was 1h 16min, 1h 14min and 1h 03min, respectively in three cases among 30, while for the remaining 27 cases it was not more than 47min. The mean error for all 30 cases was ±31min. All that indicates that the proposed method is of quite good precision in the early post mortem period, with an accuracy of ±1h for a 95% confidence interval. On the basis of the presented method, TOD can be also calculated at the death scene with the use of a proposed portable electronic device (TOD-meter).