Prosecutors in Schaffhausen, the country’s northern-most canton, were notified on Monday by a law firm that an assisted suicide with the Sarco capsule had taken place at a forest hut near the German border.

The controversial device — named Sarco for ‘sarcophagus’ — allows the occupant to press a button which fills the sealed pod with nitrogen, leading to death by hypoxia within minutes.

A campaign group called The Last Resort announced earlier this year that the device would soon be used for the first time in Switzerland.

Inventor Philipp Nitschke previously claimed the device would be legal in Switzerland, despite concerns raised by doctors and prosecutors.

The person who died in the Sarco pod on Monday is reported to have been a 64-year-old woman from the United States.

Schaffhausen’s public prosecutor’s office says it has opened criminal proceedings against several people for inducement and aiding and abetting suicide, contrary to Article 115 of the Swiss Criminal Code, and several people have been taken into police custody.

In a statement issued yesterday, prosecutors added: “Based on official and investigative secrecy, no further information is currently being provided. The presumption of innocence applies.”