Police in the northern Schaffhausen canton said the capsule had been used Monday at a forest hut, after which several people were taken into custody -- and are now facing criminal proceedings.

The capsule has raised a host of legal and ethical questions in Switzerland, where active euthanasia is banned but assisted dying has been legal for decades.

The space-age looking Sarco capsule, first unveiled in 2019, is a portable, human-sized pod which replaces the oxygen inside it with nitrogen, causing death by hypoxia.

It is self-operated by a button on the inside, providing death without medical supervision.

The Last Resort organisation, an assisted dying group, presented the Sarco pod in Zurich in July, saying they expected it to be used for the first time within months and saw no legal obstacle to its use in Switzerland.

In a statement to AFP, The Last Resort said that the person who died was a 64-year-old woman from the midwestern United States.

The woman, who was not named, "died using the Sarco device" at approximately 4:01 pm (1401 GMT) on Monday.

"The public prosecutor's office of the canton of Schaffhausen has opened criminal proceedings against several people for inducement and aiding and abetting suicide... and several people have been placed in police custody," the canton's police force said in a statement.

The public prosecutor's office was informed by a law firm at 4:40 pm on Monday that an assisted suicide had taken place that afternoon "at a forest hut in Merishausen", the statement said.

The police, the forensic emergency service and the public prosecutor's office "went to the crime scene".

The Sarco suicide capsule was secured and the deceased taken away for an autopsy.

"Several people in the Merishausen area were taken into police custody," the statement said.

The 3D-printable capsule cost more than 650,000 euros ($720,000) to research and develop in the Netherlands over 12 years.

The Dutch newspaper De Volkskrant said one of its photographers had been arrested by the Schaffhausen police on Monday.

The use of the Sarco pod use came as Switzerland's interior minister said it was not compliant with Swiss law.

"The Sarco suicide capsule is not legally compliant in two respects," Elisabeth Baume-Schneider said during a parliamentary question and answer session on Monday.

"Firstly, it does not meet the requirements of product safety law and therefore cannot be placed on the market. Secondly, the corresponding use of nitrogen is not compatible with the purpose article of the Chemicals Act," she said.

To use the Sarco, the person wishing to die must first pass a psychiatric assessment.

The person climbs into the purple capsule, closes the lid, and is asked automated questions such as who they are, where they are and if they know what happens when they press the button.