Police in northern Switzerland said on Tuesday that several people have been detained and a criminal case opened in connection with the suspected death of a person in a new “suicide capsule”.

The “Sarco” suicide capsule, which has never been used before, is designed to allow a person inside to push a button that injects nitrogen gas into the sealed chamber. The person is then supposed to fall asleep and die by suffocation in a few minutes.

Prosecutors in Schaffhausen canton were informed by a law firm that an assisted suicide involving use of the Sarco capsule had taken place on Monday near a forest cabin in Merishausen, police said in a statement.

It said “several people” were taken into custody and prosecutors opened an investigation on suspicion of incitement and accessory to suicide.

Dutch newspaper Volkskrant reported on Tuesday that police had detained one of its photographers who wanted to take pictures of the use of the Sarco.

It said Schaffhausen police indicated the photographer was being held at a police station but declined to give a further explanation.

The newspaper declined to comment further when contacted by the Associated Press (AP).

Exit International, an assisted suicide group based in the Netherlands, has said it is behind the 3D-printed device that cost more than one million dollars to develop.

In a statement, the group said a 64-year-old woman from the US Midwest – it did not specify further – who had suffered from “severe immune compromise” had died on Monday afternoon near the German border using the Sarco device.

It said Florian Willet, co-president of The Last Resort, a Swiss affiliate of Exit International, was the only person present and described her death as “peaceful, fast and dignified”.

Dr Philip Nitschke, an Australian-born trained doctor behind Exit International, has previously told the AP that his organisation received advice from lawyers in Switzerland that use of the Sarco would be legal in the country.

In the Exit International statement on Tuesday, Dr Nitschke said he was “pleased that the Sarco had performed exactly as it had been designed … to provide an elective, non-drug, peaceful death at the time of the person’s choosing”.

Swiss law allows assisted suicide so long as the person takes his or her life with no “external assistance” and those who help the person die do not do so for “any self-serving motive”, according to a government website.

Switzerland is among the only countries in the world where foreigners can travel to legally end their lives, and is home to a number of organisations that are dedicated to helping people kill themselves.

Some legislators in Switzerland have argued that the law is unclear and have sought to close what they call legal loopholes.

On Monday, health minister Elisabeth Baume-Schneider was asked in the Swiss parliament about the legal conditions for the use of the Sarco capsule, and suggested its use would not be legal.

“On one hand, it does not fulfil the demands of the product safety law, and as such, must not be brought into circulation,” she said.

“On the other hand, the corresponding use of nitrogen is not compatible with the article on purpose in the chemicals law.”

– The Samaritans can be contacted on 116123 or email [email protected].