One press of a button and you can end your life with a swift injection of potassium chloride. That is the boast of Roger Kusch, once one of Germany's most promising conservative politicians and now the improbable promoter of a mercy-killing machine.

If the “Perfusor”, designed to sidestep strict laws banning assisted suicide, goes into production then Germany rather than Switzerland could soon become the destination of choice for those seeking to kill themselves.

Some 700 patients, including several terminally ill Britons, have travelled to Zurich where the self-help organisation Dignitas arranges suicide. Assisted suicide has been legal in Switzerland since 1942 providing a doctor has been consulted and the patient is aware of the consequences of his decision.

But Dignitas has come under fire for experimenting with suicide techniques. According to video evidence presented to the Zurich state prosecutor, patients have been placing plastic bags over their heads and feeding in helium gas.

In four cases being studied by the prosecutor, one patient died after nine minutes and three after between 25 and 50 minutes. “The bodies twitched for several minutes,” Andreas Brunner, the prosecutor, said. Swiss papers compared the gassing method to the techniques used in the Third Reich.

Dignitas argued that gassing was faster than poisonous injection because helium did not require a prescription, eliminating the cost and the time involved in finding a sympathetic doctor.

These revelations have struck home in Germany, where direct assistance in mercy killing is illegal and where most Dignitas clients live. The theme is highly sensitive because of the systematic euthanasia practised by the Nazis on the physically and mentally disabled.

“The machine is simply an option for fatally ill people,” said Dr Kusch, 53, presenting the green machine that looks like a cross between an electric transformer and a paint spraygun. “Nobody is forced to use it but I do believe that it will contribute to a debate that is moving thousands of people.”

The machine would be lent or rented so that the patients could insert the needles themselves and then push the button releasing the potassium chloride, used to execute Death Row prisoners in some US states. Supporters say the machine will bring about death in seconds. Death Row cases suggest the process could be longer. One of the responsibilities of the organisation lending the machine will be to consult with doctors about the exact dosage.

Merely lending the machine to a prospective suicide is not, say legal experts, against German law. Gerhard Strate, a defence lawyer from Hamburg, said: “As long as the sick person is fully conscious and aware, then lending the machine to him is no more illegal than lending him a kitchen knife or a razor blade. It becomes illegal only if the potential suicide asks someone in the room to press the button for him.”

Dr Kusch, whose doctorate is in law not medicine, was once a political star. Under Chancellor Kohl, he was head of the internal security department and in 2001 became Justice Minister in Hamburg. Tipped for high office, he became the victim of Christian Democratic infighting, left the party and set up his own grouping that actively propagated mercy killing for the terminally ill. He has now withdrawn from politics and he has established a legal practice, which will specialise in offering advice to old people worried about the legal and tax implications of ending their lives.

The tabloid Bild Zeiting denounced Dr Kusch's machine as “perverse” and other media outlets have tentatively skirted around the taboo.

The case of Chantal Sebires has moved Germany and triggered a debate. The Frenchwoman, allergic to pain-relieving morphine, killed herself after suffering an incurable tumour. Die Welt said: “Opponents of assisted suicide stress that palliative medicine and new pain therapies make it unnecessary. The Sebires case showed that these have their limits.”

“For believing Christians the self determination of death is a violation, an attempt to interfere with the Creation which can be determined only by God,” the paper wrote on Easter Sunday, “but can believers really demand that non-believers adopt their point of view?”

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