The impact of anatomy variation on temperature based time of death estimation.

Temperature-based time of death estimation using simulation methods such as the finite element method promise higher accuracy and broader applicability in nonstandard cooling scenarios than established phenomenological methods. Their accuracy depends crucially on the simulation model to capture the actual situation, which in turn hinges on the representation of the corpse's anatomy in form of computational meshes as well as on the thermodynamic parameters. While inaccuracies in anatomy representation due to coarse mesh resolution are known to have a minor impact on the estimated time of death, the sensitivity with respect to larger differences in the anatomy has so far not been studied. We assess this sensitivity by comparing four independently generated and vastly different anatomical models in terms of the estimated time of death in an identical cooling scenario. In order to isolate the impact of shape variation, the models are scaled to a reference size, and the possible impact of measurement location variation is excluded explicitly by finding measurement locations leading to minimum deviations. The thus obtained lower bound on the impact of anatomy on the estimated time of death shows, that anatomy variations lead to deviations of at least 5-10%.

Stabbed by motorcycle? Reconstruction of an unusual traffic accident.

The reconstruction of traffic accidents involving powered two-wheelers (PTWs) frequently proves to be a challenging task. A case in which a fatal head-on crash of a PTW with a small truck where only minor vehicles damage was observed but resulted in isolated fatal chest trauma is discussed here. External examination of the corpse revealed two lacerations on the back, at the first glance implying sharp trauma. Based on the accident traces, the technical expert assumed an emergency break of the PTW rider resulting in a rotation of the PTW in terms of a wheelie on the front wheel. The first contact between the PTW rider and the tail end of the small truck probably occurred with the upper side of the helmet, and then, the back handle of the PTW caused the stab-like injuries followed by compression of the rider between the small truck or asphalt and the PTW. Based on the few accident traces available, neither a reconstruction of the pre-impact velocity nor a detailed reconstruction of the PTW rider kinematics was possible. However, using an interdisciplinary approach, the principal collision position as well as the injury mechanisms could be reconstructed.

Bone marrow haemophagocytosis indicates severe infection with severe acute respiratory syndrome coronavirus 2.

AIMS: Haemophagocytosis in the bone marrow of patients who have succumbed to coronavirus disease 19 (COVID-19) has not been widely studied. The aims of the present study were to perform morphological analyses and morphometry of haemophagocytosis in the bone marrow of patients with severe COVID-19, and to correlate the findings with the clinical course of the disease. METHODS AND RESULTS: In this single-centre study performed at the University Hospital Jena, bone marrow specimens of 15 deceased patients who had experienced a severe course of COVID-19 were sampled from the vertebral column during autopsy. Slides of the bone marrow were stained with routine stains or immunohistochemically, and further examined for haemophagocytosis by the use of light microscopy. To substantiate the morphological findings, additional slides were stained for CD163 and morphometry was performed. In all bone marrow samples, an increase in cellularity was found. Haemophagocytes with erythrophagocytosis were detected in 67% of the deceased patients. In tissues with low numbers of haemophagocytes or ill-defined haemophagocytes, an increase in iron deposits was frequently seen. Morphological findings were then correlated with several important clinical data, and the HScore (probability of having a reactive hemophagocytic syndrome) was calculated to posthumously confirm the diagnosis of secondary haemophagocytic lymphohistiocytosis. The median duration of disease and the hospitalisation time were lower in patients with haemophagocytosis (n = 10) than in patients without haemophagocytosis (n = 5). In addition, patients with haemophagocytes showed increased inflammatory parameters 2-5 days prior to death, in contrast to patients without haemophagocytes. CONCLUSIONS: Haemophagocytosis is a common finding in the bone marrow of deceased individuals with severe COVID-19, and may indicate fatal severe acute respiratory syndrome coronavirus 2 infections.

Fully automatic CT-histogram-based fat estimation in dead bodies.

Post-mortem body cooling is the foundation of temperature-based death time estimations (TDE) in homicide cases. Forensic science generally provides two types of p.m. body cooling models, the phenomenological and the physical models. Since both of them have to implement important individual parameters like the quantity of abdominal fat explicitly or implicitly, a more exact quantification and localization of abdominal fat is a desideratum in TDE. Particularly for the physical models, a better knowledge of the abdominal fat distribution could lead to relevant improvements in TDEs. Modern imaging methods in medicine like computed tomography (CT) are opening up the possibility to register the quantity and spatial distribution of body fat in individual cases with unprecedented precision. Since a CT-scan of an individual's abdominal region can comprise 1000 slices as an order of magnitude, it is evident that their evaluation for body fat quantification and localization needs fully automated algorithms. The paper at hand describes the development and validation of such an algorithm called "CT-histogram-based fat estimation and quasi-segmentation" (CFES). The approach can be characterized as a weighted least squares method dealing with the gray value histogram of single CT-slices only. It does not require any anatomical a priori information nor does it perform time-consuming feature detection on the CT-images. The processing result consists in numbers quantifying the amount of abdominal body fat and of muscle-, organ-, and connective tissue. As a by-product, CFES generates a quasi-segmentation of the slices processed differentiating fat from muscle-, organ-, and connective tissue. The tool is validated on synthetic data and on CT-data of a special phantom. It was also applied on a CT-scan of a dead body, where it produced anatomically plausible results.

Automatic CT-based finite element model generation for temperature-based death time estimation: feasibility study and sensitivity analysis.

Temperature-based death time estimation is based either on simple phenomenological models of corpse cooling or on detailed physical heat transfer models. The latter are much more complex but allow a higher accuracy of death time estimation, as in principle, all relevant cooling mechanisms can be taken into account.Here, a complete workflow for finite element-based cooling simulation is presented. The following steps are demonstrated on a CT phantom: Computer tomography (CT) scan Segmentation of the CT images for thermodynamically relevant features of individual geometries and compilation in a geometric computer-aided design (CAD) model Conversion of the segmentation result into a finite element (FE) simulation model Computation of the model cooling curve (MOD) Calculation of the cooling time (CTE) For the first time in FE-based cooling time estimation, the steps from the CT image over segmentation to FE model generation are performed semi-automatically. The cooling time calculation results are compared to cooling measurements performed on the phantoms under controlled conditions. In this context, the method is validated using a CT phantom. Some of the phantoms' thermodynamic material parameters had to be determined via independent experiments.Moreover, the impact of geometry and material parameter uncertainties on the estimated cooling time is investigated by a sensitivity analysis.

Fatal abdominal injuries in a bicycle-pedestrian collision - Reconstruction using multibody simulation.

Fatal bicycle-pedestrian collisions do not occur frequently and thus are rarely reported in literature. Pedestrians in bicycle-pedestrian accidents often sustain severe craniocerebral injuries caused by a collision induced fall with head impact on the road surface. We describe a case where a pedestrian crossing a road was hit by a bicycle. Hematomas of the left lower leg and of the left flank/abdomen were found to be caused by the primary impact. However, the fatal injuries were found to be contralateral with a rupture of the right renal pedicle, a rupture of the right lobe of the liver and a tear of the vena cava. Neither the bicycle impact nor a fall onto the road surface could cause these injuries. Multibody simulation (PC Crash 9.2) revealed entanglement between the bicyclist and the pedestrian followed by a contact interaction between the pedestrian laying on the road surface and the falling bicyclist. In forensic case work post-crash contact interactions between the bicyclist and the pedestrian should be considered as a potential source of severe injuries.

Biomechanical assessment of the injury risk of stomping.

Forensic case work as well as literature shows that severe head injuries, e.g., with basilar fractures and cerebral hemorrhages due to stomps can be seen; however, there is no data basis concerning contact forces and potential influencing factors. The objective of this work was to generate a data basis of contact forces in stomping by performing experimental measurements and subsequent statistical analyses. Fifty-five volunteers participated in the present study. Each participant performed several stomps onto force plates with sturdy/soft footwear as well as with/without an elastic layer imitating the scalp. Ground reaction forces induced by jumps were also measured for sturdy and soft footwear. The results show statistically significant dependencies between maximum ground reaction forces and body weight and body height. A statistically significant influence of footwear on stomping force could only be found in tests with an elastic layer and in the jumping setup. Mean maximum stomping forces for the female volunteers were between 4694 and 5970 N; male volunteers were able to produce mean peak stomping forces between 8494 and 9016 N. Jumping forces were approximately twice the stomping forces for both male and female test persons. Regardless of footwear and gender, it can be claimed that a forceful stomp or jump to someone's head supported on the ground can cause facial and skull fractures. Thus, forceful stomps or jumps to someone's head can cause potential fatal injuries independent of footwear, gender, or fitness level.

Evaluation of biochemical assays and optimization of LC-MS-MS analysis for the detection of synthetic urine.

Ensuring specimen validity is an essential aspect of toxicological laboratories. In recent years, substituting authentic urine specimens for synthetic urine (SU) has become increasingly popular. Such SU products consist of components expected in normal urine and show physiological values for specific gravity and pH. Thus, standard specimen validity testing may fail in revealing adulteration by SU. The present study investigated three methods to distinguish authentic and SU specimens: enzymatic detection of uric acid, the commercially available Axiom Test True SU and liquid chromatography coupled with (tandem) mass spectrometry (LC-MS-MS) analysis of 10 endogenous biomolecules. Additionally, novel direct markers of SU were investigated. Two specimen sets were analyzed by each method. Specimen set A consisted of eight SU products purchased from the Austrian/German market and 43 urine specimens from volunteers of known authenticity, which underwent double-blind analysis. Specimen set B consisted of 137 real urine specimens submitted for drug testing, which were selected due to initial suspicious test results in adulteration testing and reanalyzed by all three methods. Uric acid and LC-MS-MS-based endogenous biomolecule testing showed 100% sensitivity and specificity for set A. The commercial test had 87.5% sensitivity and 97.7% specificity for set A. For set B, uric acid and LC-MS-MS analysis showed almost similar results, even if uric acid was missing one presumptive authentic urine specimen according to LC-MS-MS findings. Nearly half of the SU assignments for the commercial test were presumptive false positives. New SU markers were observed for SU products from the Austrian/German market. One specimen in set B had both an endogenous biomolecule pattern and SU markers suggesting urine dilution with SU. In conclusion, several analytes or methods should be used rather than one, and the most reliable results are achieved if both indirect and direct markers of urine substitution are analyzed.

Setting the boundaries of prior influence on kinship relation testing: the case of many hypotheses.

Kinship relation and, in particular, paternity probability estimation using a Bayesian approach require the input of a priori probabilities of different hypotheses. In practical case work, a priori probabilities or priors, for short, must often be estimated using only common sense and symmetry arguments because in most cases, there is no evidence-based information on which the priors may be determined. In contrast to the accuracy of the likelihood probabilities or the likelihood ratios, the precision of the priors is usually very poor. Thus, a quantitative estimation of the priors' influence on the paternity probability is desirable. This article presents exact formulae to define sharp minimum and maximum boundaries of posterior probabilities as a function of prior boundaries which may be applied in kinship cases with varying numbers of hypotheses and also presents two case examples.

[Experimental throws with a knife to clarify a case of domestic violence]. / Messerwurf--Experimentelle Untersuchungen in einem Fall von "häuslicher Gewalt".

For an expert opinion, the course of events in a conflict resulting in a 3 cm deep and 1.8 cm wide stab wound on the neck of a woman was to be reconstructed. Based on the statements of witnesses, there were three possible scenarios: 1. The knife was thrown from a distance of about one meter. 2. The knife had accidentally slipped from the hand. 3. The knife was deliberately used for a stab to the neck of the victim. The experimental setup comprised the knife presumably causing the injury and four comparable knives. The victim was represented by a pig carcass. The results of the test throws are presented and the sequence of movements is assessed as to the most probable course of events. Four male and three female subjects performed test throws which were documented by video recordings and measurements of the penetration depth. Six of the seven subjects were able to generate stab wounds by throwing the knives, whereas a knife accidentally slipping from the hand never caused a stab wound in the tests.

Database of post-mortem rectal cooling cases under strictly controlled conditions: a useful tool in death time estimation.

The most common method used in determining the estimated time since death in the early post-mortem phase is back-calculation based on rectal temperature decrease. Cooling experiments are essential for model generation and validation. Post-mortem temperature models are necessary to perform back-calculations. Thus far, cooling experiments have not been performed under controlled environmental conditions. The present study provides data on 84 post-mortem cooling experiments under strictly controlled environmental conditions. For a period of 5 years, starting in 2003, deceased persons with a known time of death and known environmental conditions at the death scene were transferred to a climatic chamber for the process of body cooling. The environmental temperature was programmed to the death scene temperature and kept constant throughout the process of body cooling. Rectal and ambient temperatures were measured every minute. Relevant case-specific information was summarized in a FileMaker database. The database serves as a reference tool for the comparison of real cases in forensic routine and to check the plausibility of model-derived estimates.

Quality measures for fully automatic CT histogram-based fat estimation on a corpse sample.

In a previous article a new algorithm for fully automatic 'CT histogram based Fat Estimation and quasi-Segmentation' (CFES) was validated on synthetic data, on a special CT phantom, and tested on one corpse. Usage of said data in FE-modelling for temperature-based death time estimation is the investigation's number one long-term goal. The article presents CFES's results on a human corpse sample of size R = 32, evaluating three different performance measures: the τ-value, measuring the ability to differentiate fat from muscle, the anatomical fat-muscle misclassification rate D, and the weighted distance S between the empirical and the theoretical grey-scale value histogram. CFES-performance on the sample was: D = 3.6% for weight exponent α = 1, slightly higher for α ≥ 2 and much higher for α ≤ 0. Investigating τ, S and D on the sample revealed some unexpected results: While large values of τ imply small D-values, rising S implies falling D and there is a positive linear relationship between τ and S. The latter two findings seem to be counter-intuitive. Our Monte Carlo analysis detected a general umbrella type relation between τ and S, which seems to stem from a pivotal problem in fitting Normal mixture distributions.

Influence of measurement errors on temperature-based death time determination.

Temperature-based methods represent essential tools in forensic death time determination. Empirical double exponential models have gained wide acceptance because they are highly flexible and simple to handle. The most established model commonly used in forensic practice was developed by Henssge. It contains three independent variables: the body mass, the environmental temperature, and the initial body core temperature. The present study investigates the influence of variations in the input data (environmental temperature, initial body core temperature, core temperature, time) on the standard deviation of the model-based estimates of the time since death. Two different approaches were used for calculating the standard deviation: the law of error propagation and the Monte Carlo method. Errors in environmental temperature measurements as well as deviations of the initial rectal temperature were identified as major sources of inaccuracies in model based death time estimation.

Body mass and corrective factor: impact on temperature-based death time estimation.

Model-based methods play an important role in temperature-based death time determination. The most prominent method uses Marshall and Hoare's double exponential model with Henssge's parameter determination. The formulae contain body mass as the only non-temperature parameter. Henssge's method is well established since it can be adapted to non-standard cooling situations varying the parameter body mass by multiplying it with the corrective factor. The present study investigates the influence of measurement errors of body mass m as well as of variations of the corrective factor c on the error of the Marshall and Hoare-Henssge death time estimator t (D). A formula for the relative error of t (D) as a function of the relative error of m is derived. Simple approximations of order 1 and 0 nevertheless yield acceptable results validated by Monte Carlo simulations. They also provide the rule of thumb according to which the quotient of the standard deviations D(t (D)) of the estimated death time and D(m) of the body mass is equal to the quotient of the estimated death time t (D) and the body mass m (D(t (D))/D(m) ≈ t (D)/m). Additionally, formulae and their approximations are derived to quantify the influence of Henssge's body mass corrective factor c on death time estimation. In a range of body masses between 50 and 150 kg, the relative variation of the body mass corrective factor is approximately equal to the relative variation of the death time (Δt (D) = (t (D)/c)Δc). This formula is applied and compared to computations and to experimental cooling data with good results.

Temperature-based death time estimation in near equilibrium: Asymptotic confidence interval estimation.

Temperature based death time estimation (TDE) is severely limited in situations where body core temperature has almost decreased to ambient temperature. The TDE method of Marshall/Hoare and Henßge (MHH) defines a lower bound TK for body core temperature below which the time p.m. should be stated to be >10h only. A recent study (Potente et al., 2017 [10]) established a new method, called variance-bias-tradeoff (VBT) complementing MHH in constructing a right-side-half-infinite 97.5%-confidence interval for such 'near equilibrium'-situations. It seemingly proved the validity for all body core temperatures T

Forensic Odontology: Automatic Identification of Persons Comparing Antemortem and Postmortem Panoramic Radiographs Using Computer Vision.

PURPOSE: In forensic odontology the comparison between antemortem and postmortem panoramic radiographs (PRs) is a reliable method for person identification. The purpose of this study was to improve and automate identification of unknown people by comparison between antemortem and postmortem PR using computer vision. MATERIALS AND METHODS: The study includes 43 467 PRs from 24 545 patients (46 % females/54 % males). All PRs were filtered and evaluated with Matlab R2014b including the toolboxes image processing and computer vision system. The matching process used the SURF feature to find the corresponding points between two PRs (unknown person and database entry) out of the whole database. RESULTS: From 40 randomly selected persons, 34 persons (85 %) could be reliably identified by corresponding PR matching points between an already existing scan in the database and the most recent PR. The systematic matching yielded a maximum of 259 points for a successful identification between two different PRs of the same person and a maximum of 12 corresponding matching points for other non-identical persons in the database. Hence 12 matching points are the threshold for reliable assignment. CONCLUSION: Operating with an automatic PR system and computer vision could be a successful and reliable tool for identification purposes. The applied method distinguishes itself by virtue of its fast and reliable identification of persons by PR. This Identification method is suitable even if dental characteristics were removed or added in the past. The system seems to be robust for large amounts of data. KEY POINTS: · Computer vision allows an automated antemortem and postmortem comparison of panoramic radiographs (PRs) for person identification.. · The present method is able to find identical matching partners among huge datasets (big data) in a short computing time.. · The identification method is suitable even if dental characteristics were removed or added.. CITATION FORMAT: · Heinrich A, Güttler F, Wendt S et al. Forensic Odontology: Automatic Identification of Persons Comparing Antemortem and Postmortem Panoramic Radiographs Using Computer Vision. Fortschr Röntgenstr 2018; 190: 1152 - 1158.

Confidence intervals in temperature-based death time determination.

Marshall and Hoare's double exponential model with Henßge's parameters is a well known method for temperature based death time estimation. The authors give 95%-confidence intervals for their method. Since body cooling is a complex thermodynamical process, one has to take into account a potential bias of the estimator. This quantity measures the systematic error of the estimators underlying model. For confidence interval radius calculation a bias of 0 is presupposed, therefore the actual probability of the true death time value to lie in the 95%-confidence interval can be much lower than 95% in case of nonvanishing bias. As in case of nonstandard conditions the confidence intervals have a probability of containing the true death time value which even in case of small corrective factor errors of Δ = ± 0.1 can be substantially smaller than the 95% claimed, the paper presents a formula for confidence intervals which keep a 95% probability in case of error Δc ⩽ ± 0.1.

Simulating irradiation power density on body surface in postmortem cooling.

Irradiation poses a major problem to determining the time since death by temperature-based methods. Neither empirical nor heat-flow postmortem cooling models have so far been able to assess irradiation. Heat-flow models seem overall better suited to calculate irradiation because of their direct relation to the physics of heat transfer. An implementation of irradiation boundary conditions in heat-transfer models requires the knowledge of the irradiation power density on the body surface. The present study develops formulae and implements them in a computer program to simulate the radiation power density on a semi-cylindrical body surface coming from irradiation by a rectangular radiant heater nearby or from the sun. The formulae are valid for deliberate geometrical arrangements of either body and radiant heater or body and sun. In case of the radiant heater scenario shading functions for the shading of the semi-cylinder by itself and by the rear panel of the radiant heater are developed. In case of the sun scenario only the shading by the semi-cylinder is relevant. In examplary analyses of typical irradiation scenarios the power density coming from a 2000W radiant heater nearby on the body surface amounted to a maximum of 418W/m2, the radiation power density originating from sunlight on a clear summer afternoon in middle-Europe amounted to a maximum of 422W/m2.

Modelling postmortem surface cooling in continuously changing environmental temperature.

Heat loss depends on the temperature gradient between body surface and environment. Skin cooling data in the forensic literature are scarce and models for skin cooling have not been developed. The dependence on the environmental temperature is a general problem in modelling postmortem cooling processes; most models of rectal cooling are therefore restricted to constant ambient temperatures. Since surface in contrast to core temperatures are highly sensitive to changes of ambient temperature, a model for skin cooling has to take into account such changes. The present study provides an estimator for the time-dependent function of the temperature decrease of the skin and presents a model of the cooling process. The formulae are developed on the basis of skin cooling data of the exposed skin of the forehead in a 40-year-old female (163 cm, 62.1 kg). The single exponential Newtonian model for the surface temperature T(S) valid for constant environmental temperature T(E):T(S)(t)=(T(S)(0)-T(E))e(-lambda(t))+T(E) is localized to small time intervals. By Taylor series expansions a differential equation directly providing an estimator for the temperature decrease rate lambda is derived. The solution of this differential equation represents the extended Newtonian model valid for non-constant environmental temperatures and non-constant temperature decrease rates. The extended model is tested successfully by reinserting the estimated values for the temperature decrease rate: the reconstructed and the measured skin temperature decrease curves completely overlap each other. The temperature decrease rate is a function of the difference between skin and environmental temperature and of the actual change of the skin temperature. A scatter plot of this function shows a structured cloud of points lying in one plane. The temperature decrease rate can thus be parametrized by a simple affine equation with three coefficients determined by linear regression. Inserting the affine equation in the extended Newtonian model leads to an inhomogeneous, non-linear differential equation which is solved by recursion. With knowledge of the initial temperature and the course of the environmental temperature the decrease of the skin temperature can be predicted with very good results. The model is validated with good results in 12 further experimental skin cooling curves of ten different individuals.

Supravital energy production in early post-mortem phase - estimate based on heat loss due to radiation and natural convection.

The temperature-based determination of the time since death in the early post-mortem (pm) period plays an important role in medico-legal practice. In contrast to the common opinion according to which convection and conduction are mainly responsible for post-mortem heat loss, a considerable part of energy is emitted by thermal radiation. The present paper concentrates on the heat loss due to radiation and natural convection. Since both heat transfer mechanisms depend on the temperature gradient between skin and environment, the skin temperature was measured in corpses of different constitution (lean, medium and obese) and its decrease fitted by a single-exponential model. Heat loss due to radiation was calculated according to the non-linearized form of the law of Stefan and Boltzmann, heat loss due to natural convection according to the semi-empirical thermodynamic laws; the shape of the body in supine position was approximated to a semi-cylinder of finite length. The power due to radiation ranged between 386kJ/h (lean) and 550kJ/h (obese), that due to natural convection between 307kJ/h (lean) and 429kJ/h (obese) initially. Cumulative energy loss amounted to 2167kJ (lean) and 4239kJ (obese) by radiation and 1485kJ (lean) and 2922kJ (obese) by natural convection up to 20h pm. The energy loss due to radiation plus natural convection initially exceeded the energy loss due the decrease of the energy content of the body (mass x heat capacity x temperature decrease). This surplus can be explained only by exothermal processes in the phase of intermediary life and directly provides lower bounds for supravital energy production. Cumulative supravital energy ranges between 1139kJ up to 5h pm in the lean and 2516kJ up to 10h pm in the obese corpses. The courses of supravital energies and powers are presented as functions of time. Under standard conditions like still air (no forced convection) and insulating ground (little conductive heat transfer), the lower bounds represent estimates for total supravital energy production.