Nitrogen inhalation suicide pacts.

Suicide pacts usually result in simultaneous deaths by mutual arrangement. While nitrogen and helium gas inhalation are being increasingly used in solitary suicide attempts, for some reason they have been rarely utilised in suicide pacts. A search of autopsy files at Forensic Science SA over a 15-year period (2003-2017) was undertaken to determine how often this method of joint suicide occurs. Only two cases were found. Case 1 comprised a 64-year-old husband and wife (who had a history of multiple sclerosis). They were found deceased in a vehicle with two empty cylinders of nitrogen gas. Case 2 comprised an 87-year-old man (who had a history of ischaemic heart disease) and his 81-year-old wife who were found deceased with plastic bags over their heads, with plastic tubes connecting the bags to opened cylinders of nitrogen. The deaths in all cases were due to nitrogen-induced asphyxiation, in the latter instance augmenting plastic-bag asphyxia. Although suicide pacts have previously usually involved carbon-monoxide toxicity or drug overdose, it is possible that dissemination of information on the use of inert gases in individual suicide attempts may alter the methods used in future.