A right-to-die activist questioned for murder after the death of a womanusing a suicide podhas died by assisted suicide. Florian Willet suffered a mental health crisis after he was arrested by Swiss police in September last year, said Philip Nitschke, the inventor of the Sarco suicide capsule. Mr Willet was the director of Last Resort, the Swiss suicide organisation, which was set up to facilitate the use of the Sarco. The 47-year-old German was investigated for aiding and abetting suicide. Prosecutors also investigated whether he had strangled the woman, but that was ruled out before he was released in December after 70 days of pre-trial detention. "Gone was his warm smile and self-confidence. In its place was a man who seemed deeply traumatised by the experience of incarceration and the wrongful accusation of strangulation," said Mr Nitschke, the director ofExit International, the pro euthanasia group. The Australian former physician, who is called "Doctor Death" by his critics, said Mr Willet sought help and was admitted to a psychiatric hospital twice before his death on May 5. Mr Nitschke told the Dutch newspaper Volkskrant that Mr Willet had died in Germany with the help of an unnamed specialised organisation. It is not known how he died. "To describe Florian is to talk of a man who was thoughtful, caring, funny, and friendly. He was an easy person to be around," said Mr Nitschke, who lives in the Netherlands. "But most of all, Florian was kind. Florian was also passionate about a person'sright to choose when to die." Suicide is legal under certain conditions in Switzerland, but the pod had never been used before and there were warnings it would be illegal. Mr Willet was the only person present when a 64-year-old American woman, who has not been named, pressed a button to fill the Sarco pod with nitrogen gas. The woman had suffered from an immune disease. He informed the authorities after her death in a forest in the canton of Schaffhausen but was arrested, along with several others, including a newspaper photographer. They were later released but Mr Willet, a former media spokesman for euthanasia clinic Dignitas, continued to be detained. He had described thefirst death in the controversial Sarco podas "peaceful, fast and dignified". The 3D-printable capsule cost about £550,000 to research and develop in the Netherlands over 12 years. Last Resort has said that future reusable pods could cost about £12,600. "By the age of five I took my own dying by suicide into consideration," Mr Willet said in an interview before his arrest. He revealed his father had died by suicide when he was 14 and claimed he was "completely fine with it." He added: "I was extremely sad because I loved my father. But, I understood immediately my father wanted to do this because he was a rational person, which means that expecting him to remain alive just because I need a father would mean extending his suffering." Broaden your horizons with award-winning British journalism. Try The Telegraph free for 1 month with unlimited access to our award-winning website, exclusive app, money-saving offers and more.