Identification of mechanical asphyxiation in cases of attempted masking of the homicide.

Five homicides are described that had remained unexplained as to the causes of death after gross pathology. Although general signs of asphyxiation were present, they were lacking injuries specific of strangulation or oro-nasal occlusion. The diagnoses of asphyxiation were established by microscopical investigation of the lung and confirmed by subsequent police inquiries. An oro-nasal occlusion was involved in three cases, a strangulation or an oro-nasal occlusion, in another case. The victims were young and healthy. Toxicological investigations remained negative in four cases; one victim was anaesthetized by bromazepam and ether and had a blood alcohol concentration of 80 mg/100 ml. Lung histology and electron microscopy revealed acute emphysema, the development of a haemorrhagic-dysoric syndrome and a microembolism syndrome. With regard to the haemorrhagic-dysoric syndrome, the development of alveolar-interstitial edema is particularly important. This finding may also be diagnosed by light microscopy in semi-thin sections. It is emphasized that the combined action of several pathomechanisms is responsible for the rapid manifestation of the pulmonary lesions. Especially, the haemorrhagic-dysoric syndrome is brought about by the combined action of inspiratory intrapulmonary vacuum and raised intracapillary pressure. The complex pattern allows to compile the diagnosis of mechanical asphyxia even if there is no corresponding injury.