Sensitivity of temperature-based time since death estimation on measurement location.

Rectal temperature measurement (RTM) from crime scenes is an important parameter for temperature-based time of death estimation (TDE). Various influential variables exist in TDE methods like the uncertainty in thermal and environmental parameters. Although RTM depends in particular on the location of measurement position, this relationship has never been investigated separately. The presented study fills this gap using Finite Element (FE) simulations of body cooling. A manually meshed coarse human FE model and an FE geometry model developed from the CT scan of a male corpse are used for TDE sensitivity analysis. The coarse model is considered with and without a support structure of moist soil. As there is no clear definition of ideal rectal temperature measurement location for TDE, possible variations in RTM location (RTML) are considered based on anatomy and forensic practice. The maximum variation of TDE caused by RTML changes is investigated via FE simulation. Moreover, the influence of ambient temperature, of FE model change and of the models positioning on a wet soil underground are also discussed. As a general outcome, we notice that maximum TDE deviations of up to ca. 2-3 h due to RTML deviations have to be expected. The direction of maximum influence of RTML change on TDE generally was on the line caudal to cranial.

Delayed occurrence of traumatic aortic dissection? Biomechanical considerations and literature.

Chronic aortic dissections and pseudoaneurysms caused by chest trauma are rare and generally have to be critically distinguished from non-traumatic dissections and aneurysms. We present a well-documented case of a post-traumatic aortic dissection that ruptured about 9 months after chest trauma. A motorcyclist sustained fractures of the forearm and chest trauma with paravertebral rib serial fractures and hemopneumothorax. Nine months after the accident, echocardiography revealed a pseudoaneurysm that ruptured 3 months later and 1 month prior to the planned surgery. An autopsy showed pericardial tamponade following a rupture of the dissected aorta. Accident scene documentation was consistent with a head-on collision of the motorcycle against the left front side of the car. The relative speed was about 55 km/h. Aggravation of unspecific symptoms after discharge, initial CT imaging, and the absence of atherosclerosis or medial necrosis hold for a post-traumatic genesis of the dissection in our case. Initially, the accident insurance company rejected the regulation. In the second instance, they revised rejection based on our interdisciplinary expert opinion.

Slip and tilt: modeling falls over railings.

Falls over railings are frequent case scenarios forensic experts are confronted with. An important issue is the differentiation of accidental and non-accidental falling scenarios. From a biomechanical point of view, this is a challenging task and should be addressed in a multifactorial approach. This work presents a simplified mechanical model in terms of a cranked rod that can be used in cases without relevant dynamic components in terms of pushing or jumping. If the anti-slip and the anti-tilt condition are violated, the possibility for a person to get over a railing should be assumed and investigated in more detail. Because our approach also involves uncertainties, the formulae should be understood to be part of a multifactorial approach. Numerical simulation, experimental reconstruction, injury pattern, and trace analysis can yield additional substantial connecting facts.

[Bridging vein injuries in shaken baby syndrome : Forensic-radiological meta-analysis with special focus on the tadpole sign]. / Brückenvenenverletzungen bei Schütteltrauma : Forensisch-radiologische Metaanalyse unter besonderer Berücksichtigung des "Tadpole"-Zeichens.

Shaken baby syndrome is a common variant of the abusive head trauma in infants and toddlers and is still subject of intensive research. In recent years, a number of radiological studies on the diagnostic and forensic relevance of injured bridging veins were conducted using different imaging modalities. The present article will give an overview on the current state of research in this field and will discuss the forensic implications. The meta-analysis of the seven currently existing studies revealed that injuries of the bridging veins and bridging vein thromboses, respectively, frequently appear as rounded, enlarged, and/or tubular structures. The "tadpole sign" may serve as a valuable tool for the identification of these formations. Especially, T2*/SWI (susceptibility-weighted imaging) sequences allow for good detectability of these lesions and should always be generated when abusive head trauma is suspected. In conclusion, it can be recommended that the presence of radiologically detectable bridging vein injuries should give reason to search for other manifestations of physical child abuse.

Forensic postmortem computed tomography in suspected unnatural adult deaths.

PURPOSE: Our study sought to evaluate validity of forensic postmortem CT in establishing cause of death (COD) in suspected unnatural adult death based on the reference standard of autopsy. METHODS: In our prospective, single-center study, 64 of 94 consecutive corpses (70.7 % male, mean age: 47.4 years) who underwent CT and autopsy between November 2013 and April 2019 were included in the analysis. Primary objective was agreement between CT and autopsy on primary COD using kappa statistics. Secondary objectives were competing COD and specific pathological findings. RESULTS: Agreement on primary COD between forensic CT and autopsy without or in consideration of toxicological and histological findings was strong (85.9 % [55 of 64 corpses]; κ = 0.83 [95 %CI: 0.74 to 0.93] and 95.3 % [61 of 64 corpses]; κ = 0.94 [95 %CI: 0.84-1.04], respectively, McNemar p = 0.03). Sensitivity and specificity of CT in identification of acute heart failure, intracranial bleeding, burns and heat shocks, gunshot wounds, polytrauma, cranio-cerebral trauma, and strangulation or hanging was 100 %, each. Acute respiratory failure was detected with a sensitivity and specificity of 100 % and 96.8 %, cuts and stab wounds with 95.2 % and 100 %, and intoxication, pneumonia, or gastrointestinal bleeding with 60.0 % and 100 %, respectively. Agreement on competing COD was moderate (51.6 %, [33 of 64 corpses]; κ = 0.47 [95 %CI: 0.40 to 0.53], p < 0.001). CONCLUSIONS: Forensic postmortem CT, complemented by external, toxicological, and histological examination was sufficiently valid to assess primary COD in the majority of suspected unnatural deaths with few restrictions.

Injury pattern and the biomechanical assessment of skull fracture risk in blows with a rubber mallet.

Acts of violence often result in blunt force trauma. On behalf of the court, forensic experts not only have to assess injuries in terms of morphology or severity, but they also have to give statements regarding the risk of potential fatal injuries. We describe a case of domestic violence where a man hit the head of his wife using a rubber mallet. His wife sustained extensive and multiple parietal scalp lacerations and avulsions with exposure of the cranial bone. A CCT revealed neither skull fractures nor intracranial injuries. Biomechanical measurements were performed using a bowling ball and an animal head representing head surrogates. In comparison to steel hammer impacts we hypothesized longer contact durations and lower maximum contact forces in blows with a rubber mallet. However, contact durations in the magnitude of 3ms do not confirm our hypothesis. The contact forces calculated based on mallet and animal head accelerations were between 2.97kN and 4.68kN. These force values are rather below the parietal fracture thresholds, explaining the absence of parietal skull fractures in the case presented. Moreover, the relatively low Young's modulus comes along with a deformation of the rubber mallet and a decrease in contact pressure. In summary, contact times could be reliably estimated, while contact forces remained largely uncertain.

Pedestrian hit by a car impacted metal pole: reconstructing the head load.

Fatal head injuries are frequently seen in pedestrians hit by motorized vehicles. In our case, the pedestrian sustained a devastating head injury with skull splitting in the mediosagittal plane. A car collided with a traffic sign causing a bending of the pole. The metal pole hit a man standing close beside it; the man had a head injury severity that is more commonly due to falling objects than due to traffic accidents. Assuming a head mass of 5 kg, simplified calculations yield maximum contact forces of ca. 36 kN exceeding mean parietal fracture forces which are in the order of magnitude of 12.5 kN. The influences of the effective body mass and the horizontal distance between the pole and the pedestrian on maximum contact forces are investigated. High contact forces in our case can be mainly explained by the comparably high impact velocity and by a partial mass transfer of the total car mass to the pole.

Biomechanical approach for the assessment of contacts with deformable objects.

Forensic and biomechanical assessment in case of blunt force trauma can be a challenging task especially when deformable striking objects are used. Evaluations solely based on empirical knowledge can lead to misjudgments. Semi-quantitative and quantitative investigations give the forensic assessment a scientific basis comprising experimental and calculation methods. Based on a real case where a car wheel was used as a striking object, our work presents a simple test setup for contact force estimation in head contacts with deformable contact partners. Our approach combines experimental measurements using a single accelerometer and calculations applying the conservation of linear momentum and Newton's second law. Both experimental and calculation results are discussed in terms of validity, reproducibility, and plausibility. With regard to our case, we can conclude that the injury pattern without skull fractures does not confound multiple strikes with a wheel. Skull fractures and potential fatal injuries had not to be expected assuming a head-carcass contact in case of a non-supported head. The approach presented can be applied to any case where deformable or uncommon blunt objects are used.

Improving stomach content based death time determination by maximum probability estimation.

Stomach content based death time estimation (SCE), is a well-known technique in forensic sciences. Among more qualitatively oriented approaches the content percentage based method SCE by Tröger, Baur and Spann yields quantitative results and gives stochastic error measures for its outputs. This is possible since the methods estimator, which we call transformed expectation estimator (TEE) as well as the probability distribution of the time between last meal and death are determined numerically, though in SCE the estimator and confidence intervals are presented graphically only. Our articles outcomes are.

Influence of striking technique on maximum striking velocities-experimental and statistical investigation.

Forensic experts often have to assess injury and fatality risks in the context of violent blunt force trauma. Maximum striking velocities in one- and two-handed strikes with a rod-like implement can be of particular interest. Current literature lacks studies addressing this problem. The purpose of this study was therefore to measure and analyse maximum striking velocities in one-handed and two-handed strikes in female and male volunteers. We hypothesised higher striking velocities in two-handed strikes compared to one-handed strikes. Fifty volunteers performed one- and two-handed strikes from top to bottom using a steel rod of 65 cm length and 1000 g weight. A Qualisys™ Motion Analysis system registered displacements of reflecting markers fixed to the rod as well as to the volunteer's body. In one-handed strikes, the mean maximum striking velocity was 17.2 m/s in the female sample and 23.9 m/s in the male sample. Statistically not significantly different maximum striking velocities were found in two-handed strikes with mean values of 18.3 m/s in the female sample and 24.2 m/s in the male sample. Female and male volunteers also yielded similar mean maximum striking velocities in two-handed strikes comparing 'overhead' and 'overshoulder' striking techniques. In conclusion, the striking technique did not relevantly influence maximum striking velocities in our setup.

Maximum striking velocities in strikes with steel rods-the influence of rod length, rod mass and volunteer parameters.

In blunt force trauma to the head caused by attacks with blunt instruments, contact forces can be estimated based on the conservation of momentum if impact velocities are known. The aims of this work were to measure maximum striking velocities and to examine the influence of rod parameters such as rod mass and length as well as volunteer parameters such as sex, age, body height, body mass, body mass index and the average amount of physical exercise. Steel rods with masses of 500, 1000 and 1500 g as well as lengths of 40, 65 and 90 cm were exemplarily tested as blunt instruments. Twenty-nine men and 22 women participated in this study. Each volunteer performed several vertical strikes with the steel rods onto a passive immobile target. Maximum striking velocities were measured by means of a Qualisys motion capture system using high-speed cameras and infrared light. Male volunteers achieved maximum striking velocities between 14.0 and 35.5 m/s whereas female volunteers achieved values between 10.4 and 28.3 m/s. Results show that maximum striking velocities increased with smaller rod masses and less consistently with higher rod lengths. Statistically significant influences were found in the volunteers' sex and average amount of physical exercise.

Influence of hypo- and hyperthermia on death time estimation - A simulation study.

Numerous physiological and pathological mechanisms can cause elevated or lowered body core temperatures. Deviations from the physiological level of about 37°C can influence temperature based death time estimations. However, it has not been investigated by means of thermodynamics, to which extent hypo- and hyperthermia bias death time estimates. Using numerical simulation, the present study investigates the errors inherent in temperature based death time estimation in case of elevated or lowered body core temperatures before death. The most considerable errors with regard to the normothermic model occur in the first few hours post-mortem. With decreasing body core temperature and increasing post-mortem time the error diminishes and stagnates at a nearly constant level.

Calibration and parameter variation using a finite element model for death time estimation: The influence of the substrate.

The most established method for temperature based death time estimation is based on an empirical double exponential model. New physically based approaches using numerical simulation techniques are subject of current research. A major advantage of such models is the possibility to incorporate non-standard boundary conditions. The aim of this study was to investigate the influence of the substrate on the cooling rate of a body in the early postmortem phase. A finite element model was used for parameter variation in terms of different substrate materials. Simulation results showed a considerable influence of substrate material on the postmortem cooling rate of a body. From a thermodynamical point of view, comparability between measurements on a steel trolley and real cooling scenarios with common substrates like normal floors, asphalt or soil remains questionable. It could be shown that not only the type of substrate but also its composition can have a considerable influence on the postmortem body cooling rate.

Do multiple temperature measurements improve temperature-based death time estimation? The information degradation inequality.

The accuracy of the input parameter values limits the accuracy of the output values in forensic temperature-based death time estimation (TDE) like in many scientific methods. A standard strategy to overcome this problem is to perform multiple measurements of the input parameter values, but such approaches are subject to noise accumulation and stochastic dependencies. A quantitative mathematical analysis of advantages as well as disadvantages of multiple measurements approaches (MMAs) was performed. The results are A general stochastic model of MMA. The information degradation inequality quantifying gains and losses of MMAs. Example calculations of the information degradation inequality for the following two MMAs relevant to TDE: o Multiple successive rectal temperature measurements o Multiple synchronous body layer temperature measurements Neither multiple successive rectal temperature measurements nor multiple synchronous body layer temperature measurements seem to significantly improve death time estimation. MMAs are superior to the single measurement approach only in the very early body cooling phase.

Temperature based forensic death time estimation: The standard model in experimental test.

The determination of the time since death is essential to forensic homicide investigations since the time of death represents the presumed time of the offence. Erroneous death time estimates may lead to false acquittal or conviction of suspects. Since its introduction 30years back, the nomogram method by Henßge has been established as the standard procedure of temperature-based death time determination in the early post-mortem period. The present study provides an independent investigation of the validity of its death time estimates and their corresponding 95%-confidence intervals. Comparison to post-mortem cooling curves recorded under controlled conditions of 84 suddenly deceased with known death times yielded the following results: Since in the light of our experiments the validity of the nomogram method seems to be problematic, death time estimates - and particularly their 95%-confidence interval limits - have to be interpreted carefully and should only be restrictively used as court evidence to support or refute alibis. Systematic overestimation of the post-mortem interval in bodies of high mass and large surface area must be taken into account.

Adenomyosis and endometriosis. Re-visiting their association and further insights into the mechanisms of auto-traumatisation. An MRI study.

PURPOSE: In a series of publications, we had developed the concept that uterine adenomyosis and pelvic endometriosis as well as endometriotic lesions at distant sites of the body share a common pathophysiology with endometriosis constituting a secondary phenomenon. Uterine auto-traumatization and the initiation of the mechanism of tissue injury and repair (TIAR) were considered the primary events in the disease process. The present MRI study was undertaken (1) to corroborate this concept by re-visiting, in view of discrepant results in the literature, the association of adenomyosis with endometriosis and (2) to extend our views concerning the mechanisms of uterine auto-traumatization. PATIENTS AND METHODS: MRI was performed in 143 women attending our center, in whom, on the basis of transvaginal sonography (TVS) and historical data, such as documented endometriosis and dysmenorrhea of various degrees of severity, the presence of uterine adenomyosis was suspected. In addition to the measurement of the diameter of junctional zone (JZ) of the anterior and posterior walls in the mid-sagittal plane, the diagnosis of adenomyosis was based on visualization, in that all planes were analyzed with scrutiny. By this method of "visualization" all transient enlargement of the JZ, such as peristaltic waves of the archimyometrium and sporadic neometral contractions that might mimic adenomyotic lesions could be excluded. At the same time, this method allowed to lower the limit of detection in terms of thickness of the JZ for assured diagnosis of adenomyosis. Furthermore, the localizations of the individual lesions, their shapes and patterns were described. RESULTS: With the method of 'visualization', the diagnosis of uterine adenomyosis could be verified in 127 of the 143 patients studied. The prevalence of endometriosis in adenomyosis was 80.6% and the prevalence of adenomyosis in endometriosis was 91.1%. As concluded from their localization within the uterine wall, the adenomyotic lesions predominantly developed in the median region of the upper two-thirds of the uterine wall. Cystic cornual angle adenomyosis was a distinct phenomenon that was only observed in patients suffering from extreme primary dysmenorrhea. Aside from this, the majority of the patients complained of primary dysmenorrhea (80%). On the basis of these findings and the fact that particularly extreme primary dysmenorrhea is associated with high intrauterine pressure, menstrual 'archimetral compression by neometral contraction' has to be considered as an important cause of uterine auto-traumatization in addition to uterine peristalsis and hyperperistalsis. Both mechanical functions of the non-pregnant uterus exert their strongest power in the upper region of the uterus, which is compatible with the predominant localization of the adenomyotic lesions. CONCLUSIONS: The data confirm our previous results of a high association of adenomyosis with endometriosis and vice versa. Our view of the mechanism of uterine auto-traumatization by mechanical functions of the non-pregnant uterus has to be extended, in that 'archimetral compression by neometral contractions' could be realized as the predominant cause of mechanical strain to the non-pregnant uterus. The data of this study confirm our concept of the etiology and pathophysiology of adenomyosis and endometriosis in that the process of chronic proliferation and inflammation is induced at the level of the archimetra by chronic uterine auto-traumatization. Furthermore, with respect to the diagnosis of uterine adenomyosis (and consequently endometriosis) this study shows a high degree of accordance between the findings in real-time TVS and MRI.

The forensic relevance of hypothermia in living persons--literature and retrospective study.

In practical case work, forensic experts can be confronted with the problem of estimating cold exposure times in the living given the core body temperature after exposure. However, the current literature lacks systematic studies of body cooling in the living and cooling rates under different circumstances. The objective of our study is to provide working forensic specialists with a collection of cases to use for comparison in order to estimate the accident time or assault time using the cooling rates from similar cases. Excessive data mining led to 18 cases from the literature, 16 cases from Jena's patient files and 9 cases from the database of the Institute for Legal Medicine in Jena. Cooling rates between 0.15 °C/h and 4.1 °C/h were found in adults. Newborns showed rates between 1.2 °C/h and 28.5 °C/h. Potential factors that influence the cooling process in the living are discussed and the possibilities and limitations of the data acquisition and -evaluation are considered.