Helium is an inert gas that among other things is used medically to alleviate the symptoms of airway obstruction, as part of a diving mix in deep-sea diving or as balloon gas. In recent years the so-called right-to-die literature has suggested suffocation with inhaled helium as an effective and peaceful means of self-deliverance for terminally ill patients. Helium displaces oxygen and carbon dioxide and can thus lead to asphyxia. We report three cases of suicidal asphyxiation with helium gas that were examined at the Department of Forensic Medicine Vienna within three months in 2006. In all three cases, autopsy was unrewarding from the point of view of gross pathology. Special autopsy techniques and devices are required for collection of the gas from the lungs. Gas-chromatography is used to examine the gas for helium; however, this requires replacement of the carrier gas, which is itself usually helium. The fact that three people in Vienna committed suicide using this method within a short period of time, together with the abundance of detailed how-to literature on the Internet, suggests a possible future increase in the number of deaths associated with the inhalation of inert gases, particularly helium. Because of the diagnostic obstacles involved, it is necessary to rely on good death-scene investigation for situational evidence when the body is discovered.
Three-dimensional (3D) crime scene documentation using 3D scanners and medical imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) are increasingly applied in forensic casework. Together with digital photography, these modalities enable comprehensive and non-invasive recording of forensically relevant information regarding injuries/pathologies inside the body and on its surface. Furthermore, it is possible to capture traces and items at crime scenes. Such digitally secured evidence has the potential to similarly increase case understanding by forensic experts and non-experts in court. Unlike photographs and 3D surface models, images from CT and MRI are not self-explanatory. Their interpretation and understanding requires radiological knowledge. Findings in tomography data must not only be revealed, but should also be jointly studied with all the 2D and 3D data available in order to clarify spatial interrelations and to optimally exploit the data at hand. This is technically challenging due to the heterogeneous data representations including volumetric data, polygonal 3D models, and images. This paper presents a novel computer-aided forensic toolbox providing tools to support the analysis, documentation, annotation, and illustration of forensic cases using heterogeneous digital data. Conjoint visualization of data from different modalities in their native form and efficient tools to visually extract and emphasize findings help experts to reveal unrecognized correlations and thereby enhance their case understanding. Moreover, the 3D case illustrations created for case analysis represent an efficient means to convey the insights gained from case analysis to forensic non-experts involved in court proceedings like jurists and laymen. The capability of the presented approach in the context of case analysis, its potential to speed up legal procedures and to ultimately enhance legal certainty is demonstrated by introducing a number of representative forensic cases.
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