The use of 3D-CT in weapon caused impression fractures of the skull, from a forensic radiological point of view

Post-mortem CT in the investigation of homicides

AIM

To investigate the reliability of post-mortem computed tomography (PMCT) in a case series of homicides involving blunt-force, sharp-force, and ballistic trauma.

MATERIALS AND METHODS

The study investigates 16 homicide cases that underwent PMCT before autopsy. Two radiologists assessed the PMCT examinations and the data were compared to the forensic pathology findings. Data were organised in broad categories: foreign bodies, external injuries, soft-tissue and organ injuries, fractures, air in cavities, fluid collections, random pathology, and wound track. Findings were organised by systems: head and neck, thorax, abdomen and pelvis, extremities. Cohen's kappa statistics were used to assess observer agreement.

RESULTS

Six gunshot-related homicides (37.5%), seven sharp-force-related homicides (43.75%), two blunt-force-related deaths (12.5%), and one homicide due to mechanical asphyxia (1.25%) were analysed. A total of 64 fractures were reported by the pathologists, 67 by radiologist 1 and 68 by radiologist 2. Agreement was deemed substantial in all cases. Pathologists failed to report gas in cavities while radiologists underreported superficial injuries.

CONCLUSION

An overall observation was that less accurate findings were produced by the blinded radiologist in comparison to the non-blinded one. The extremeness of homicides obscured the interpretation of PMCT leading to the observed discrepancies. The combination of PMCT and autopsies is deemed optimal when investigating homicidal events.

Was it an axe or an adze? A cranial trauma case study from the Late Neolithic - Chalcolithic site of Cova Foradada (Calafell, Spain)

OBJECTIVE

To reconstruct the etiology of a perimortem injury observed on a Neolithic - Chalcolithic cranium (5060 - 4400 yrs cal. BP).

MATERIALS

A cranium of an old adult male individual belonging to a collective burial from Cova Foradada site (Calafell, Tarragona, Spain).

METHODS

The cranium was analyzed macroscopically and microscopically using micro-CT scan.

RESULTS

The fracture on the right parietal bone presents characteristics of perimortem trauma. The morphology of the point of impact allows for the interpretation of this fracture as a result of impact by an object with a straight and sharp edge. In addition, the same cranium presents two healed antemortem injuries.

CONCLUSIONS

The object that most likely caused the cranial fracture was a stone adze. The blow occurred from behind the individual, possibly by a right-handed attacker.

SIGNIFICANCE

The potential to link cranial fractures with specific tools increases our understanding of interpersonal violence during the Neolithic.

LIMITATIONS

It is not possible to infer if this cranial injury was related to a large-scale intergroup confrontation or an intragroup violent event.

SUGGESTIONS FOR FURTHER RESEARCH

To investigate additional similar sites in the northeastern Iberian Peninsula to better characterize the fracture pattern caused by stone axes and adzes as well as other objects used as weapons during the Neolithic - Chalcolithic ages.

The effect of different imaging techniques for the visualisation of evidence in court on jury comprehension

Evidence presented within a courtroom should be clear so that the members of the jury can understand it. The presentation of distressing images, such as human remains, can have a negative effect on the jury since photographic images may evoke emotional responses. Therefore, it is important to understand how other visual mediums may improve comprehension, bias, or distress individuals. For this study, 91 individuals were randomly assigned one of three visual evidence formats in a mock courtroom exercise. These included photographs, 3D visualisations, or a 3D-printed model. The results show that the use of 3D imaging improves the juror’s understanding of technical language used within a courtroom, which in turn better informs the juror’s in their decision-making.

Virtual animation of victim-specific 3D models obtained from CT scans for forensic reconstructions: Living and dead subjects

Post-mortem CT scanning (PMCT) has been introduced at several forensic medical institutions many years ago and has proved to be a useful tool. 3D models of bones, skin, internal organs and bullet paths can rapidly be generated using post-processing software. These 3D models reflect the individual physiognomics and can be used to create whole-body 3D virtual animations. In such way, virtual reconstructions of the probable ante-mortem postures of victims can be constructed and contribute to understand the sequence of events. This procedure is demonstrated in two victims of gunshot injuries. Case #1 was a man showing three perforating gunshot wounds, who died due to the injuries of the incident. Whole-body PMCT was performed and 3D reconstructions of bones, relevant internal organs and bullet paths were generated. Using 3ds Max software and a human anatomy 3D model, a virtual animated body was built and probable ante-mortem postures visualized. Case #2 was a man presenting three perforating gunshot wounds, who survived the incident: one in the left arm and two in the thorax. Only CT scans of the thorax, abdomen and the injured arm were provided by the hospital. Therefore, a whole-body 3D model reflecting the anatomical proportions of the patient was made combining the actual bones of the victim with those obtained from the human anatomy 3D model. The resulted 3D model was used for the animation process. Several probable postures were also visualized in this case. It has be shown that in Case #1 the lesions and the bullet path were not consistent with an upright standing position; instead, the victim was slightly bent forward, i.e. he was sitting or running when he was shot. In Case #2, one of the bullets could have passed through the arm and continued into the thorax. In conclusion, specialized 3D modelling and animation techniques allow for the reconstruction of ante-mortem postures based on both PMCT and clinical CT.

Specific Characteristics of Injuries Inflicted by Claw Hammer

Claw hammers have the specific characteristic of having two distinct ends: one a flat head of variable form, the other bifurcated. So the use of this tool as a blunt instrument will cause varying injuries. The authors present two clinical cases of assault with a claw hammer. Examinations revealed two types of wound. A first injury composed of integumentary lacerations and underlying bone injuries in terms of "shape" suggested the use of a blunt instrument. A second injury made up of damage showing two parallel wounds or two wounds located one in the extension of the other suggested the use of an object with a bifurcated end. The combination of both types of injury should alert examiners to the possibility of the use of a claw hammer in causing the injuries in order to help direct investigators in their investigations and in the search for the weapon used.

Lethal interpersonal violence in the Middle Pleistocene

Evidence of interpersonal violence has been documented previously in Pleistocene members of the genus Homo, but only very rarely has this been posited as the possible manner of death. Here we report the earliest evidence of lethal interpersonal violence in the hominin fossil record. Cranium 17 recovered from the Sima de los Huesos Middle Pleistocene site shows two clear perimortem depression fractures on the frontal bone, interpreted as being produced by two episodes of localized blunt force trauma. The type of injuries, their location, the strong similarity of the fractures in shape and size, and the different orientations and implied trajectories of the two fractures suggest they were produced with the same object in face-to-face interpersonal conflict. Given that either of the two traumatic events was likely lethal, the presence of multiple blows implies an intention to kill. This finding shows that the lethal interpersonal violence is an ancient human behavior and has important implications for the accumulation of bodies at the site, supporting an anthropic origin.

Imaging for homicide investigations

The authors present the opportunities of the application of post-mortem imaging, focusing on post-mortem computed tomography and post-mortem computed tomography angiography in modern forensic investigation of homicide cases. The paper is based on scientific publications related to the subject from ca. the past 10 years, supplemented by the authors' own experiences. The article is illustrated with reconstructions based on the authors' own cases related to homicide due to ballistic/sharp/blunt trauma. As is shown, the results of evaluation of post-mortem computed tomography allow better diagnosis, documentation and visualisation of forensic examinations.