Advocacy groups behind a “suicide capsule” have announced the suspension of applications for its use, pending the completion of a criminal investigation into a woman’s voluntary death from its first use.

Florian Willet, president of The Last Resort, a Switzerland-based organization, is currently being held in pretrial detention, as confirmed by both The Last Resort and its Australian affiliate, Exit International, both advocating for the right to assisted suicide.

Swiss police initiated the arrest of Willet and several others following the death of a 64-year-old American woman, who became the first individual to utilize the device for voluntary ending of life last month. The device, known as the “Sarco,” was used in a forest in the northern Schaffhausen region of Switzerland near the German border on Sept. 23.

Authorities have confirmed that other individuals who were initially detained in relation to the woman’s death have been released from custody.

The woman reportedly suffered from a severe immune compromise.

Assisted suicide is legal in Switzerland, with laws permitting what is known as “death with dignity” as long as the individual ends their life without “external assistance” and any individuals assisting them do not do so for any “self-serving motive.”

In a statement released on Sunday, the advocacy groups disclosed that as of Sept. 23, 371 individuals were in the process of applying to use the Sarco in Switzerland. However, they confirmed the suspension of applications following its initial use.

Exit International, founded by Philip Nitschke based in the Netherlands, is the driving force behind the device. The Sarco was 3D-printed and required over $1 million in development costs.

The capsule is designed to allow an individual to sit in a reclining seat within the device and initiate a nitrogen gas injection from a tank underneath into the sealed chamber by pressing a button. This process would induce the individual to fall asleep and subsequently die from suffocation within a few minutes.

Exit International has asserted that Willet was the sole individual present during the woman’s death, which the group described as “peaceful, fast and dignified.”

On the day of the woman’s death, Elisabeth Baume-Schneider, the Swiss Health Minister, informed parliament that the use of the device would be considered illegal.

However, Exit International refuted Baume-Schneider’s statement, maintaining that their legal team in Switzerland believes the Sarco’s use is compliant with Swiss law.

“Only after the Sarco was used was it learned that Ms. Baume-Schneider had addressed the issue,” the advocacy groups stated in their Sunday statement. “The timing was a pure coincidence and not our intention.”