Comparison of microscopic features of bone false starts produced by reciprocating saw blades and handsaws of the same class.

In cases of criminal dismemberment, the analysis of saw marks helps to determine the class of the saw used. The present study compared the microscopic features of experimental false starts performed on three freshly defleshed human femurs. 150 lesions were produced using three reciprocating blades and two hand saws of similar class. Two groups of tools were created according to the class of the blades: group 1 (teeth per inch = 6, alternating set) and group 2 (teeth per inch = 24, wavy set). The minimum width of the kerf was always thicker with reciprocating blades than that of the handsaw of the same class. This fact is linked to the thickness of the blades and not necessarily to the fast forth and back motion of the blades. Shape kerf profiles and shape of the walls were very confusing, with a lot of variation of the false starts caused by the reciprocating blades and the risk of misclassification (rip teeth versus crosscut teeth, alternating set versus wavy set). Striae on the kerf floor and bone islands were more consistent. The main conclusions are, first, that usual features of false starts achieved by reciprocating saw blades used in this work vary a great deal and may lead to misclassification of the saw class, and second, that no criterion has been found to differentiate reciprocating blades and handsaws. These results demonstrate that we have to be very prudent while estimating the possible saw from a false start in a real forensic case.

Sex estimation from the greater sciatic notch: a comparison of classical statistical models and machine learning algorithms.

The greater sciatic notch (GSN) is a useful element for sex estimation because it is quite resistant to damage, and thus it can often be assessed even in poorly preserved skeletons. This study aimed to develop statistical models for sex estimation based on visual and metric analyses of the GSN, and additional variables linked to the GSN. A total of 60 left coxal bones (30 males and 30 females) were analysed. Fifteen variables were measured, and one was a morphologic variable. These 16 variables were used for the comparison of six statistical models: linear discriminant analysis (LDA), regularized discriminant analysis (RDA), penalized logistic regression (PLR) and flexible discriminant analysis (FDA), and two machine learning algorithms, support vector machine (SVM) and artificial neural network (ANN). The statistical models were built in two steps: firstly, only with the GSN variables (group 1), and secondly, with the whole variables (group 2), in order to see if the models including all the variables performed better. The overall accuracy of the models was very close, ranging from 0.92 to 0.97 using specific GSN variables. When additional variables starting from the deepest point of GSN are available, it is worth to use them, because the accuracy increases. PLR (after optimization of parameters) stands out from other statistical models. The position of the deepest point of GSN (Fig. 2) probably plays a crucial role for the sexual dimorphism, as stated by the good performance of the visual assessment of this point and the fact that the A2 angle (posterior angle with the deepest point of the GSN as the apex) is included in all models.

The stereomicroscope and scanning electron microscope comparison of false starts bones produced by an oscillating autopsy saw.

In forensic anthropology, saw mark analysis plays an important role in cases of criminal dismemberment. Autopsy saw is not used by the perpetrator in cases of dismemberment, but the forensic pathologist may accidentally create false starts with this saw during an autopsy, especially while sampling bones for further analysis, and these autopsy false starts can be confused with false starts produced by the offender. In this study, the characteristics of 20 false starts were compared using stereomicroscopy (SM) and scanning electron microscopy (SEM). These bone false starts were selected at random from a previous study of 100 false starts created by an electrical oscillating autopsy saw on human femoral bones. That study had enabled the categorization of the lesions into two groups ("superficial group" and "deep group") with a 0.52 mm depth cut off, based on the dramatic differences in lesion characteristics between these two groups. In the current study, SEM confirmed the characteristics of the false starts (walls and profile shapes, striae, bone islands and bone debris were studied), and above all explained the mechanism whereby oval bone islands in deep lesions are formed. Bone islands are due to the horizontal and vertical movement of the oscillating autopsy blade.

A Case of Multiple Self-Inflicted Stab Wounds of the Neck Captured on Surveillance Video.

Multiple sharp force injuries in a victim make it difficult to distinguish between homicide and suicide. Forensic pathologists also may be unable to determine the total survival time and the survival time with physical activity due to lack of evidence. The authors report here on a case of nineteen stab wounds of the neck, which led to an initial suspicion of homicide. The scene was however captured on surveillance video, which provided a precise description of the wound mechanism and led to the injuries being reclassified as suicidal. No other description of a suicide with such a high number of severe stab wounds has been documented in the literature. The video footage provided additional information concerning survival time. Physical activity was well documented during at least 4 min after the last stab wound and the total survival period was at least 6 min, despite the perforation of both jugular veins and the trachea. Vein injuries are less rapidly lethal than artery injuries. Injuries of the major airways are not immediately lethal and do not lead to immediate incapacitation. The benefit of the video evidence is to highlight wound features that may suggest a suicidal manner and inform forensic pathologists about survival intervals after severe stab wounds to the neck.

Analysis of false starts lesions on human bones produced by two hand saws with high TPI.

Cases of criminal dismemberment are encountered in forensic pathology and forensic anthropology. Saw mark analysis aims to determine the type of saw that was used: hand saw versus electrical saw, crosscut and universal saw versus rip saw, size of the teeth ("teeth per inch" TPI), and set type. The goal of this study was to analyze using a stereomicroscope a series of 60 experimental false starts (30 lesions for each saw) produced on human bones by two different handsaws with a high TPI (15 and 32). The lesions caused by these high TPI saws have rarely been described in the forensic literature. Saw 2 (rip hacksaw with a 32 TPI and a wavy set) displayed classical features. In contrast, saw 1 (universal panel saw, TPI 15, alternating set) did not produce the expected characteristics: the minimum width of the kerf was weak, the kerf walls were straight, the striae were straight, and the kerf profile was very peculiar with a succession of peaks and dips that has not yet been described.

Analysis of false start bone lesions produced by an electrical oscillating autopsy saw.

Postmortem dismemberment results from the use of sharp or sharp blunt instruments. Saws produce specific bone lesions, and the observation of certain saw mark features allows for the recognition of certain characteristics of the saw and its teeth. At autopsy, sections of the skull and other parts of the skeleton are usually achieved using an electrical oscillating autopsy saw. In cases of dismemberment, this autopsy saw may create additional marks to those produced by the criminal activity. In order to help the forensic pathologist to differentiate the two types of marks, this experimental study used a stereomicroscope to examine 130 experimental false starts produced on animal and human bones by an oscillating autopsy saw. A flagrant succession of narrow and wide aspects of the walls (in a "figure of 8" shape), with obvious oval bone islands and undulating striae are patterns typically left behind by oscillating autopsy saws, but the depth of the false starts plays an important role in the variation of the features. In particular, superficial false starts tend to be associated with larger kerf widths, straight walls, and longitudinal bone islands.

The link between traumatic injury in soft and hard tissue.

Forensic pathology and forensic anthropology are inherently related fields. The observations made during the autopsy and the conclusions from the anthropological analysis highlight the complementarities between the two approaches. In this review, gunshot wounds, sharp force injuries, chop wounds, blunt trauma, burned bodies, mechanical asphyxia and dismemberment will be analyzed from both perspectives. The result of this systematic review is that the conclusions stemming from the presence or absence of bone injuries must be very cautious because the observation of severe bone lesions does not always mean that this trauma was the cause of death; conversely, traumatic death, and even homicide, can be associated with a complete absence of bone lesions.

Forensic answers to the 14th of July 2016 terrorist attack in Nice.

The terrorist attack of July 14, 2016 in Nice (France) was a devastating event. A man voluntarily drove a truck into a crowd gathered for the fireworks display on the seaside "Promenade des Anglais," plowing pedestrians down over more than 2 km before being shot dead. At the time of this report, a total of 86 casualties and more than 1200 formal complaints for physical and psychological injuries have been recorded. The aim of this work is to describe the forensic management of this event and its immediate aftermath. This paper reaffirms the basic tenets of disaster management: a single place of work, teamwork in times of crisis, a single communication channel with families and the media, and the validation of the identifications by a multidisciplinary commission. This paper highlights other essential aspects of the organization of the forensic effort put in place after the Nice attack: the contribution of the police at the crime scene, the cooperation between the disaster victim identification (DVI) team, and the forensic pathologists at the morgue, applying the identification (ID) process to unconscious victims in the intensive care unit, the input of volunteers, and the logistics associated with the management of the aftermath of the event. All of the victims were positively identified within 4 and a half days. For the first time in such a paper, the central role of medical students in the immediate aftermath of the disaster is outlined. The need to address the possible psychological trauma of the non-medical and even the medical staff taking part in the forensic effort is also reaffirmed.

Saw marks in bones: A study of "secondary features" of false start lesions.

In this experiment, 170 experimental false starts on human (120 lesions) and pig bones (50 lesions) were analyzed under stereomicroscope. The goal was to evaluate the potential of three "secondary" features (patterns of striae on the kerf floor, blade drift and bone islands) to diagnose saw class and saw set. We also assessed the performance of each of these features in ambiguous cases observed in a previous study, based on three main characters (minimum width of the kerf, shape of the kerf walls, and shape of the kerf profile). Among these three "secondary" features, striae on the kerf floor proved to be useful: the undulating or undulating/straight pattern of the striae on the kerf floor indicates an alternating set whereas thin and straight striae indicates a wavy set. Blade drift and bone islands may be indicative of large teeth size. These secondary features, in combination with the three main characters previously studied, may help identify the class of the saw.

Modern (forensic) mummies: A study of twenty cases.

Twenty mummies discovered in a forensic context between 2002 and 2016 were compiled in this work. 15 cases were excluded and 15 cases of forensic mummies were found in the literature. In the current work the percentage of mummification was calculated by "the rule of nines" used for describing burned injuries in livings. Dry and hot environments, emaciation, little access to flies are favorable conditions for mummification. Nevertheless mummification was also observed in other cold and humid environments. Extensive mummification (defined in this work as "at least 50% of mummification of the body skin) has occurred in as little as three weeks in the current series. The post mortem interval was estimated by indirect clues. The cause of death was usually impossible to establish.

Macroscopic and stereomicroscopic comparison of hacking trauma of bones before and after carbonization.

This experimental study examined lesions produced by a hatchet on pig femurs before and after carbonization. A total of 30 lesions were produced and analyzed using stereomicroscopy and then reexamined after carbonization. Not only was the sharp-blunt mechanism of the hacking trauma (V-shape, regularity of one edge, irregularity of the other edge, upraising, lateral pushing back, fossae dug laterally to the edge) still recognizable after carbonization; in some instances, the carbonization actually enhanced the features observed. Carbonization also did not significantly alter the measurements of the lesions. Carbonization tends to alter the structure of the bone especially in areas weakened by the blunt trauma.

Death From Butane Inhalation Abuse in Teenagers: Two New Case Studies and Review of the Literature.

The ready availability of butane makes butane abuse frequent. Fatalities are rare. This study presents two cases of death by butane overdose. The postmortem analyses were carried out using headspace gas chromatography-mass spectrometry. It revealed femoral blood butane concentrations of 18 and 22 mg/L, respectively, as well as specific combinations of adjuvants in each victim. In one of the victims, brain and fatty tissue also contained butane, pointing to chronic consumption. The originality of this study is to show that the identification of specific combinations of adjuvants can be helpful for identifying the brand of deodorant used. Also, sampling the skin and mucosa can help identify the method of drug delivery. The histological examination documented both the direct toxic effect of the gas on the respiratory mucosa and signs of chronic abuse. Volatile substance intoxications should be systematically considered in case of sudden death in a teenager.

Suicidal hanging resulting in decapitation: A case report and review of the literature.

Decapitation following suicidal hanging is rarely encountered in forensic practice. The authors report a case of suicidal hanging resulting in decapitation following a fall of 5m. This case is compared with 30 cases found in the literature. Several factors including type of rope, skin abrasion, level of the severed vertebrae, thyroid cartilage and hyoid bone injuries and vital signs are studied. The force applied to the neck and the kinetic energy were calculated. The kinetic energy (ranging from 1820 to 7310J) takes into account the weight of the victim but also the length of the rope (height of the fall). The speed of the body as it is stopped by the rope ranged between 6.49 and 14.01ms-1.

Comparison of macroscopic and microscopic (stereomicroscopy and scanning electron microscopy) features of bone lesions due to hatchet hacking trauma.

This experimental study examined the lesions produced by a hatchet on human bones (tibiae). A total of 30 lesions were produced and examined macroscopically (naked eye) and by stereomicroscopy. 13 of them were also analyzed using scanning electron microscopy. The general shape of the lesion, both edges, both walls, the kerf floor and the extremities were described. The length and maximum width of the lesions were also recorded. The microscopic analysis of the lesions led to the description of a sharp-blunt mechanism. Specific criteria were identified (lateral pushing back, fragmentation of the upraising, fossa dug laterally to the edge and vertical striae) enabling the forensic expert to conclude that a hacking instrument was used. These criteria are easily identifiable using scanning electron microscopy, but can also be observed with stereomicroscopy. Overall, lateral pushing back and vertical striae visible using stereomicroscopy and scanning electron microscopy signal the use of a hacking tool.

Sex determination using the DSP (probabilistic sex diagnosis) method on the coxal bone: Efficiency of method according to number of available variables.

The DSP method (probabilistic sex diagnosis) was applied to100 contemporary coxal bones from elderly individuals of the South of France. Ten variables with a posterior probability greater or equal to a 0.95 threshold were used. There was no statistical difference between right side and left side measurements. There was no mistake for sex assignment but the level of indetermination varied a great deal. It was higher in females than in males. The best combinations were obtained when using all 10 variables, some combination of 9 variables (all except SS or SIS or VEAC) or the first 8 variables. We conclude that the DSP method is of great interest in forensic anthropology, thanks to a very weak possibility of mistake when using the software for sex determination of the coxal bone. The main drawback is the level of indetermination that can be high depending on the available variables.

Saw marks in bones: A study of 170 experimental false start lesions.

This experimental study examined false starts because these are seldom discussed in the forensic literature and usually concern animal bones rather than human bones. We created 170 experimental false starts (50 on pig femurs and 120 on human femurs) using five different saws (4 with an alternating set of teeth, and one with a wavy set). Teeth per inch (TPI) ranged from 7 to 24. Saws were classified as either rip saws or universal saws. The bone lesions were studied using stereomicroscopy. This study focused on three features that are easily observed with a stereomicroscope: the minimum width of the kerf, the profile of the lesions (concave or convex), and the shape of the edges (narrow-wide pattern, necking in the middle, or straight pattern). These features proved to be useful clues to recognize the class of the saw. Our study found some variability between lesions but also some repetitive features that allow for the classification the handsaws studied according to class. There were also some significant differences in lesions between pig bones and human bones, suggesting that pig femurs (versus human femurs) are not always a good alternative for studying saw marks.

Bone beveling caused by blunt trauma: a case report.

The authors report a fatal case of blunt trauma to the skull caused by a rib of a beach umbrella. The skull displayed a round hole in the right temporal bone with typical internal beveling. Blunt trauma mimicking a gunshot wound (round perforation of the skull with internal beveling) is very rarely reported in the forensic literature.

Fatal heat stroke in a child entrapped in a confined space.

We report the case of a child succumbing to heatstroke caused by confinement in an icebox. The post mortem examination found cyanosis and hematomas indicating that the child had tried to get out of the container. The temperature of the body was higher than it should have been considering the rigor and delay before post mortem examination. The autopsy showed no significant injury and toxicological tests were negative. A physiological study etablished that death resulted from heatstroke, not a lack of oxygen or CO2 poisoning. We conclude that heat stroke should be considered as a possible mechanism of death even in the absence of context of environmental hyperthermia. We recommend that in these situations involving confinement, establishing the mechanism of death should be done not only on the basis of a detailed post-mortem examination to rule out other causes of death, but also based on complete physiological investigations.

Comparing discriminant analysis and neural network for the determination of sex using femur head measurements.

The measurement of the femoral head is usually considered an interesting variable for the sex determination of skeletal remains. To date, there are few published reference measurements of the femoral head in a modern European population for the purpose of sex determination. In this study, 116 femurs from 58 individuals of the South of France (Nice Bone Collection, Nice, France) were studied. Three measurements of the femoral head were taken: the vertical head diameter (VHD), the transversal head diameter (THD) and the head circumference (HC). The results show that: (i) there is no statistical difference between the right and left femurs for each of the three measurements (VHD, THD and HC). Therefore we arbitrarily chose to use the measures from the right femurs (N=58) to pursue our experiments; (ii) the measurements of the femoral head are similar to those of contemporary American populations; (iii) the dimensions of the femoral head place the measurements of the French population somewhere between Germany or Croatia, and Spain; (iv) there is no significant secular trend (in contrast with the femoral neck diameter); (v) the femoral head measurement as a single variable is useful for sex determination: a 96.5% rate of accuracy was obtained using THD and HC measurements with the artificial neural network; and a 94.8% rate of accuracy using VHD, both with the discriminant analysis and the neural network.

Positive identification by X-rays bone trabeculae comparison.

Positive (certain, absolute) identification of human remains needs a scientific comparison between ante mortem and post-mortem biologic features, as fingerprint, odontological, radiological or DNA comparisons. X-rays comparison has been extensively used, usually comparing some peculiarities such as outlines of the bones, degenerative evolution or pathological conditions. Trabeculae comparisons are sparsely underlined in the forensic literature. We report on a case of decomposed body where fingerprint, DNA and odontological comparisons were not possible. After dissecting the leg and preparing the bones, comparison of ante mortem and postmortem trabeculae led to a positive identification. It was observed that tens of radiolucencies and radiodensities drawn by the trabeculae were useful for comparison, within a very small part of bone. In the case reported here the positive identity could have been assessed only by the comparison of the first metatarsal. The statement of positive identification needs scientific criteria that will be discussed in this article.