Yann Delannoy

3D-MSCT imaging of bullet trajectory in 3D crime scene reconstruction: Two case reports

Postmortem investigations are increasingly assisted by three-dimensional multi-slice computed tomography (3D-MSCT) and have become more available to forensic pathologists over the past 20years. In cases of ballistic wounds, 3D-MSCT can provide an accurate description of the bullet location, bone fractures and, more interestingly, a clear visual of the intracorporeal trajectory (bullet track). These forensic medical examinations can be combined with tridimensional bullet trajectory reconstructions created by forensic ballistic experts. These case reports present the implementation of tridimensional methods and the results of 3D crime scene reconstruction in two cases. The authors highlight the value of collaborations between police forensic experts and forensic medicine institutes through the incorporation of 3D-MSCT data in a crime scene reconstruction, which is of great interest in forensic science as a clear visual communication tool between experts and the court.

Skull wounds linked with blunt trauma (hammer example). A report of two depressed skull fractures – Elements of biomechanical explanation

The lesions of the skull following perforating traumas can create complex fractures. The blunt traumas can, according to the swiftness and the shape of the object used, create a depressed fracture. The authors describe through two clinical cases the lesional characteristic of the blunt traumas, perforating the skull using a hammer. In both cases the cranial lesions were very typical: they were geometrical, square shaped, of the same size than the tool (head and tip of the hammer). On the outer table of the skull, the edges of the wounds were sharp and regular. On the inner table, the edges of the wounds were beveled and irregular. The bony penetration in the depressed fracture results from a rupture of the outer table of the bone under tension, in periphery, by the bend of the bone to the impact (outbending) and then, from the inner table with comminuted bony fragmentation. Breeding on the fractures of the size and the shape of the blunt objects used is inconstant and differs, that it is the objects of flat surface or wide in opposition to those of small surface area. Fractures morphologies depend on one hand on these extrinsic factors and on the other hand, of intrinsic factors (structure of the bone). To identify them, we had previously conducted experimental work on cranial bone samples. The bone was submitted to a device for three-point bending. This work had shown properties of thickness and stiffness of the various areas of the vault. Our cases are consistent with these results and illustrate the variability of bone lesions according to region and mode of use of blunt weapons. Many studies have identified criteria for identification of the weapons and the assistance of digital and biomechanical models will be an invaluable contribution with this aim in the future.

Toward the adoption of cementochronology in forensic context

Because acellular dental cementum is considered to be formed continually throughout life and to not undergo remodeling processes, cementochronology is considered to be a method with the potential for directly assessing chronological age. Considering that most previous studies on humans have assumed the superior performance of this method, it is surprising that this technique is not more widely adopted in anthropology. To understand this controversy, we highlight that there is no standardized procedure for sample preparation. The numerous technical approaches that exist impact the reliability of the method, and the recent creation of an international work group (Cementochronology Research Program) demonstrates the need for researchers to share their experience to overcome these obstacles. This paper aims to address this paradox by debating the aspects that contribute to the limited use of this method and by illustrating its potential through an application on forensic cases. A protocol, which was recently certified according to the ISO-9001, was applied to nine anthropological cases from the Forensic Medicine Institute of Lille (northern France) and compared with routine osteological and dental methods. The results show that traditional methods matched the known age due to the wide extent of their range, while the accuracy and precision of cementochronological estimates was also notable. This paper establishes that cementochronology may serve as a particularly important tool for age estimation for forensic anthropologists and should, at least, be used in addition to other methods.

Effects of the environment on bone mass: A human taphonomic study

An experiment was designed using human ribs placed in different environments to document how moisture and temperature affect the bone mass according to the postmortem interval. The bones were defleshed, weighed and partially buried, with some ribs being left unburied as controls. The ribs were weighed daily, and the mass loss was monitored over a period of 90days. The results showed that significant differences in bone mass loss exist between environments, where the bone mass loss was significantly faster in an environment with low moisture content. This mass loss is thought to be primarily associated with the desiccation of the body and then for a greater part, with the atmospheric moisture content. However, the loss of bone mass can also be explained by early alterations in the organo-mineral matrix which were highlighted by Raman spectroscopy method.

Specific Patterns of Canine Scavenging in Indoor Settings

Postmortem animal mutilations due to domestic dogs in isolated domestic deaths are taphonomic modifications regularly observed by forensic pathologists. They are rarely described in the literature; however, even though they present specific patterns. Through 41 cases, 10 at the forensic institute in Lille (France) and 31 at the New York City Office of Chief Medical Examiner (USA), plus 22 cases from the literature, specific locations and patterns of postmortem scavenging lesions are proposed. These lesions are mainly distributed in three locations: the face, especially the nose and the mouth (73.1%), the neck (43.1%), and the arm (shoulder/upper limb [29.2%], hand [26.8%]). We discuss the time span between death and scavenging, the consequences on identification, and comparison with outdoor settings. Outdoor scavenging lesions are mainly located on the trunk and limbs usually sparing the head, which strongly differs from indoor distribution and imply different animal motivations.

New Insights on the Composition and the Structure of the Acellular Extrinsic Fiber Cementum by Raman Analysis

Acellular extrinsic fiber cementum is a mineralized tissue that covers the cervical half of the tooth root surface. It contains mainly extrinsic or Sharpey’s fibers that run perpendicular to the root surface to anchor the tooth via the periodontal ligament. Acellular cementum is continuously and slowly produced throughout life and exhibits an alternating bright and dark pattern under light microscopy. However, although a better understanding of the structural background of acellular cementum is relevant to many fields, such as cementochronology, periodontology and tissue engineering, acellular cementum remains rarely studied and poorly understood. In this work, we studied the acellular cementum at the incremental line scale of five human mandibular canines using polarized Raman spectroscopy. We provided Raman imaging analysis and polarized acquisitions as a function of the angular orientation of the sample. The results showed that mineral crystals were always parallel to collagen fibrils, and at a larger scale, we proposed an organizational model in which we found radial collagen fibers, “orthogonal” to the cementum surface, and “non-orthogonal” fibers, which consist of branching and bending radial fibers. Concerning the alternating pattern, we observed that the dark lines corresponded to smaller, more mineralized and probably more organized bands, which is consistent with the zoological assumption that incremental lines are produced during a winter rest period of acellular cementum growth.

Bone Samples Extracted from Embalmed Subjects Are Not Appropriate for the Assessment of Bone Quality at the Molecular Level Using Raman Spectroscopy.

Bone samples extracted from embalmed cadavers are commonly used as controls in the study of bone. The effects of embalmment on the molecular composition of bone are unknown. The objective of this study was to determine the effect of embalmment on the molecular composition and structure of bone, as evaluated by Raman spectroscopy. Bone samples of femoral heads from five embalmed donors and five fresh-frozen donors were compared using Raman microspectroscopy with DuoScan technology. Physicochemical parameters simultaneously describing the organic and mineral phases of bone were compared using the Mann-Whitney U test. Partial least squares discriminant analysis (PLS-DA) was used to determine specific Raman spectral features of each group. Study of the mineral phase showed a 15% reduction of the mineral-to-matrix ratio (p < 0.001), an 8% decrease of type B carbonate substitution (p < 0.001), and a 2% increase in crystallinity (p < 0.001) in the embalmed donors group compared to those of the fresh donors group. Regarding the organic phase of bone, the hydroxyproline-to-proline ratio was increased by 18% in the embalmed group (p < 0.001), with no variation in both the relative proteoglycan content (GAG/CH3) (p = 0.08) and collagen maturity (p = 0.57). PLS-DA showed that the embalmed group was characterized mainly by peaks assigned to hydroxyproline, lipids, and collagen. Embalmment induces significant modifications of the molecular composition of bone. Bone samples from embalmed subjects should be avoided as controls for Raman spectroscopy studies. Preservation procedures performed prior to bone sampling should be reported in studies using human cadaver samples.

Typical external skull beveling wound unlinked with a gunshot.

Lesions of the cranial vault resulting from firearms are traditionally described in forensic medical literature with many reports illustrating atypical bone lesions carried out to the skull by gunshot wounds. The authors present this report which illustrates an external beveled skull wound, associated with internal beveling damage, caused by a stabbing injury. A partially buried human skeleton was found in a forest. The examining of the skull revealed a hole resembling the exit wound caused by a bullet and two other smaller stab wounds. No typical entering bullet wound and no other bone lesions were found. During the course of the investigation, one of the perpetrators admitted to hitting the victim, using a sickle, and to hiding the body. For this purpose, he dragged the corpse with the sickle still implanted in the skull, using it as a hook. Upon retrieving the sickle, a piece of cranial vault was removed, thus creating an external beveled wound. In order to identify the mechanism which brought about this kind of lesion, experimental work was carried out on a human skull. In this particular case, the tip of the sickle penetrated into the bone, creating a lesion that would typically be produced with a stabbing instrument when applied with vertical force. When the body was dragged, using the sickle as a hook, this was a hand-produced vertical force, which was applied in the opposite direction. It caused the tearing of a piece of bone and the creation of an outer bevel. This atypical lesion should be made known to medical examiners and pathologists in order to help investigating and understanding of the circumstances of injuries.

Forensic features of a fatal Datura poisoning case during a robbery.

Datura poisonings have been previously described but remain rare in forensic practice. Here, we present a homicide case involving Datura poisoning, which occurred during a robbery. Toxicological results were obtained by second autopsy performed after one previous autopsy and full body embalmment. A 35-year-old man presented with severe stomach and digestive pain, became unconscious and ultimately died during a trip in Asia. A first autopsy conducted in Asia revealed no trauma, intoxication or pathology. The corpse was embalmed with methanol/formalin. A second autopsy was performed in France, and toxicology samples were collected. Scopolamine, atropine, and hyoscyamine were found in the vitreous humor, in addition to methanol. Police investigators questioned the local travel guide, who admitted to having added Datura to a drink to stun and rob his victim. The victims death was attributed to disordered heart rhythm due to severe anticholinergic syndrome following fatal Datura intoxication. This is a recent case of a rare homicide involving Datura that highlights general information on Datura and discusses forensic interpretation after a previous autopsy and body embalmment.

Experimental study of Lucilia sericata (Diptera Calliphoridae) larval development on rat cadavers: Effects of climate and chemical contamination.

Household products such as bleach, gasoline or hydrochloric acid have been used to mask the presence of a cadaver or to prevent the colonization of insects. These types of chemicals affect insect development and alter the forensic entomology analysis. This study was designed to test the effects of six household products (bleach, mosquito repellent, perfume, caustic soda, insecticide and unleaded gasoline) on blowfly (Lucilia sericata, Diptera: Calliphoridae) larval development. Furthermore, the effects of climate (rain or dry conditions) on larval development were analyzed. For each replication, 100 first instars were placed on a rat cadaver on which one household product was spilled. We observed a decrease in the survival rates of the larvae but no significant effect on their development times or the adult size. The same trends were observed under rainy conditions. However, the rain altered the effects of some tested household products, especially gasoline. These results demonstrate for the first time the successful development of necrophagous larvae on chemically contaminated cadavers, and provide evidence for the range of possible effects to expect.