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.

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.

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.

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.

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.

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.

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.

Isolated body combustion: new French cases, old worldwide issues.

The authors present 2 new cases of so-called spontaneous human combustion. The first observations of isolated body combustion, to use a more appropriate term, date back to the 17th century. Its main features are that some parts of the body (usually the middle third) are badly burnt to the point of being reduced to ashes, contrasting with other well-preserved body parts and the intact or nearly intact immediate vicinity of the body. Usually, combustion occurs postmortem, and a source of heat is found near the body. High concentrations of blood alcohol are frequently found but not mandatory. In all cases, ruling out homicide is a major concern.

Comparison of extractable DNA from bone following six-month exposure to outdoor conditions, garden loam, mold contamination or room storage.

Femur bone sections from a single donor were exposed for six months to (i) outdoor conditions (exposure to sun, rain, etc.); (ii) water-vapour saturated environment favourable to mould proliferation and (iii) humic-garden soil. Following these treatments, DNA was extracted and yields were compared with that of a control bone fragment kept under optimal laboratory storage conditions. Our results demonstrate that both mould and soil are very detrimental to bone DNA conservation since more than 97% of the bone DNA was lost in these samples as compared with the control condition. Outdoor exposure gives an intermediate result with 30% of the DNA still present in the bone. Thus, environments favourable to microorganisms proliferation appear detrimental to bone DNA conservation and are a bad prognostic should bone remains be used for genetic identification purpose. Comparatively, open-air exposure is much more favourable to bone DNA analysis.

An alternative procedure for extraction of DNA from ancient and weathered bone fragments.

Bone is the most challenging tissue for DNA extraction and purification. Expensive commercial kits and specific equipments are often used in forensic and anthropology laboratories towards that goal. We present here an integrated procedure that gives satisfactory results for DNA preparation from fresh, ancient or weathered bones. Extraction is performed under simple but efficient vacuum-controlled conditions that greatly limit the risks of cross-contaminations. The whole process has been designed to minimize the need for expensive equipment and chemicals, and to be compatible with any molecular biology laboratory. In addition, no toxic reagents are necessary and the procedure is straightforward. Combined with quantitative polymerase chain reaction (qPCR), this method allows species identification and sex determination from subcellular amount of DNA (1-5 pg). In addition, enough DNA is generally obtained for human DNA profiling if necessary. The whole procedure from bone treatment to the final qPCR results takes less than 48 hours. This procedure should allow any laboratory with standard molecular biology equipment and expertise to perform bone DNA characterization whenever necessary.

Difficulties of sex determination from forensic bone degraded DNA: A comparison of three methods.

Sex determination is of paramount importance in forensic anthropology. Numerous anthropological methods have been described, including visual assessments and various measurements of bones. Nevertheless, whatever the method used, the percentage of correct classification of a single bone usually varies between 80% and 95%, due to significant intra- and inter-population variations, and sometimes variations coming from secular trends. DNA is increasingly used in a forensic context. But forensic DNA extraction from bone raises several issues, because the samples are very often badly altered and/or in very small quantity. Nuclear DNA is difficult to get from degraded samples, according to low copy number, at least in comparison with mitochondrial DNA. In a forensic context (as in a paeleoanthropological context) DNA sex determination is usually complicated by the weak amount of DNA, the degraded nature of nucleic acids, the presence of enzymatic inhibitors in DNA extracts, the possible faint amplification of Y band and the risk of contamination during either excavation or manipulation of samples. The aim of this work was to compare three methods of DNA sex determination from bones: procedure #1 using a single PCR amplification, procedure #2 using a double PCR amplification, and procedure #3 adding bleaching for decontamination of the bone, instead of simply rubbing the bone. These processes were applied to samples of bones (49 samples coming from 39 individuals) that were in various states of post mortem alteration. The main results are the following. (i) No DNA could be extracted from three skulls (parietal bones, mastoid process), the compact bone of one rib, and the diaphysis of one femur; (ii) there was a contamination in three skulls; and (iii) the Y band did not appear in two male cases, with one of the three procedures (male tibia, procedure #2) and with procedures #2 and #3 (male femur). This study emphasises the main issue while working with altered bones: the impossibility to extract DNA in some cases, and, worth of all, the contamination of the sample or the faint amplification of Y band which leads to a wrong sex answer. Multiple and significant precautions have to be taken to avoid such difficulties.

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.

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.

Scanning electron microscopy analysis of experimental bone hacking trauma of the mandible.

The authors report on a macroscopic and microscopic study of human mandible bone lesions achieved by a single-blade knife and a hatchet. The aim of this work was to complete the previous data (scanning electron microscopy analysis of bone lesions made by a single-blade knife and a hatchet, on human femurs) and to compare the lesions of the femur with those of the mandible. The results indicate that the mandible is a more fragile bone, but the features observed on the mandible are quite similar to those previously observed on the femur. This work spells out the main scanning electron microscopy characteristics of sharp (bone cutting) and blunt (exerting a pressure on the bone) mechanisms on human bone. Weapon characteristics serve to explain all of these features.

Fatal cerebral malaria diagnosed after death in a French patient.

We report on the case of a French citizen who was found dead in his home, 4 days after returning from Cameroon. The patient died of imported malaria, as revealed by the postmortem investigations. Few such cases have been reported throughout the world. This article reviews deaths due to malaria diagnosed at the time of autopsy in France between 1995 and 2005. We conclude that the nonspecific symptoms of malaria can lead to a misdiagnosis and the need for a forensic expert to intervene at the scene of death, which usually occurs in the home. We will remind forensic pathologists of the clinical, biologic, and forensic aspects of this infectious disease. In particular, the uses of microbiologic analyses, the QBC malaria test and the Core malaria Pan/Pv/pf test as well as brain tissue histology will be reviewed.

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.

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.

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.

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.

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.