A maverick German politician is under investigation after he yesterday admitted helping a healthy elderly woman to kill herself.

The announcement by Roger Kusch , part of his campaign to change the laws governing suicide, was met with confirmation that state prosecutors are looking into the case.

Although Mr Kusch took detailed steps to stay within the law, including videoing the entire episode, investigators want to establish whether he exerted any kind of pressure on the woman.

Bettina S, 79, had contacted Roger Kusch because she was afraid that she might have to move into a care home. Within weeks of their first meeting she was dead.

“Her last words were, 'Auf Wiedersehen',” Mr Kusch, 53, a lawyer who was once an up-and-coming Christian Democrat politician, said. He added that the farewell, “see you again”, was spoken in jest by a woman happy to leave the world.

Now Mr Kusch wants Germany to replace Switzerland as the destination of choice for people tired of life. Encouraged by the Swiss organisation Dignitas, prospective suicides from across Europe have been travelling to Switzerland to die on their own terms.

More than half of the 141 people who killed themselves with the help of Dignitas last year came from Germany, a country where mercy killing has had a particular stigma since the days of the Nazis' forced euthanasia programme.

Mr Kusch is trying to get Germany to change its attitudes to suicide. When he unveiled his design for a push-button suicide machine this year, Bettina S made contact with him.

They decided to make her suicide a model for how Germans could be assisted in taking their own lives without legal consequences. Instead of putting Mr Kusch's machine to the test, however, the two chose to rely on a fatal mixture of medications.

“I came to her apartment in Würzburg at about 11 o'clock last Saturday morning,” Mr Kusch, who has no medical training, said. Within half an hour she was preparing the suicide cocktail, he said. Mr Kusch then left the room. When he returned after three hours, Bettina S was dead.

The exact procedures used by Mr Kusch were important, designed to keep him within the law and to demonstrate that people could help someone to die without risking jail. “Mercy killing” — “killing on request”, in the German terminology — is punishable by between six months and five years in jail.

To be liable for prosecution the assister would have to be actively involved — for example, injecting a fatal dose. Mr Kusch did not do this; to back up his case, he recorded the entire process on a video camera.

Someone assisting in a suicide could be charged with failure to act in an emergency if he or she did not call a doctor when the person trying to die lost consciousness. That carries a potential one-year jail term.

Mr Kusch sidestepped this problem by leaving the room after Bettina S had drunk the contents of one of her glasses. Merely “aiding suicide” is not a criminal offence: it is legal to buy rope for a friend or relative knowing that he or she could hang themselves with it.

Mr Kusch did not even take that risk and insisted that Bettina S — a former hospital worker — obtained the medicines herself.

In nine hours of videotape recorded with Mr Kusch over the past weeks, Bettina S said that she wanted to send a signal to others in her predicament.

“If accompanying me until shortly before my death gives you arguments that could persuade politicians to change the law, then my death will have been of some use to other people,” she said,

Politicians and social workers were outraged at Mr Kusch's next gesture: he called a press conference and showed the footage of Bettina S.

In part, the political establishment is nervous that Germany will end up going down the road of the Swiss, tolerating assisted suicides in undignified places such as car parks or using methods such as pumping gas into a plastic bag fastened around the head.

But there is also a fear that Mr Kusch is reaching out not only to those suffering from degenerative and incurable conditions, but also to people who are simply afraid of a change in their living conditions.

Bettina S lived alone in her apartment and seems to have suffered from no more than diabetes and rheumatic pains. She was, however, terrified of being moved into a retirement home and chose to die instead.

Critics of Mr Kusch argue that his duty was to re-assure her about moving rather than paving the way for a suicide.

“What Mr Kusch has done, in my view, is sick and inhuman,” Beate Merk, the Bavarian Justice Minister, said. “Every reasonable person would have addressed her fears and given her support. Society shouldn't be moving towards mercy killing but rather improving information about palliative medicine and taking better care of people living alone.”

Mr Kusch is an unusual champion of the right to suicide. He qualified as a judge, was a respected adviser to the chancellors Helmut Kohl and Gerhard Schröder and seemed set for the top ranks of politics when he became justice minister of Hamburg.

But he broke with the Christian Democrats to form his own party, Homeland Hamburg, using his platform to campaign for a change in the law on suicide.

The letter of the law

— Article 216 of the German Criminal Code punishes “killing on request” with from six months to five years in jail

— Article 323c allows for a one- year jail sentence for failing to assist in an emergency - ie, when a prospective suicidal person loses consciousness

— Article 212 can be used sometimes against a person found guilty of persuading someone to commit suicide, with a charge of indirect manslaughter punishable by five to fifteen 15 years in jail

— Helping a prospective suicidal person to obtain the materials or medication needed to carry out the act is not usually viewed as a criminal offence

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