Swiss assisted suicide organisation Dignitas is under growing pressure, as questions about its finances and urns of ashes found in Lake Zurich coincide with plans for a law that would make it harder for foreigners to end their life in Switzerland.
Existing Swiss legislation on assisted suicide is brief and extremely liberal.
The practice is permitted, the law states, as long as those involved in it are not selfishly motivated and do not make a profit out of it.
The lack of more specific regulations stems from a long-held and widely accepted belief among the Swiss that the right to make an end-of-life decision is personal and individual, and should not be the subject of interference by the state.
But as assisted suicide organisations such as Exit and Dignitas have grown, some concerns have emerged.
New proposals drafted by the Swiss government could force Dignitas, which - unlike Exit - has many foreign patients, to radically change its procedures.
Urns in the lake
The discovery of dozens of urns containing human ashes in Lake Zurich has served to focus attention once again on just what exactly assisted suicide groups are allowed to do.
It remains unclear who put the urns into the lake but there have been claims that Dignitas may have been involved: all the urns bore the label of the crematorium used by the organisation.
One German woman has come forward to say her stepmother's ashes were put in the lake by Dignitas, despite her wish to be buried next to her husband.
And at least one former employee of Dignitas claims she was present when urns were dumped in the lake. Soraya Wernli says she left the organisation five years ago, after becoming concerned that Dignitas had become profit-motivated.
"Dignitas has become a business worth millions," she told the BBC.
Mrs Wernli, who says she remains a firm supporter of the right to choose the moment of death, has taken her concerns to the police, and she is in favour of more regulation for assisted suicide organisations.
The founder of Dignitas, Ludwig Minelli, is firmly opposed.
Mr Minelli will not comment on the case of the urns, because it is the subject of an investigation, but, in a rare interview, he did agree to talk about how Dignitas works.
"There are no state rules but we have our own rules," Mr Minelli told the BBC. "The first is that we never precipitate an assisted suicide, every step must be initiated by the member and not by us."
Dignitas has helped more than 1,000 people die in the past 12 years, many of them foreigners who come to Switzerland precisely because their own countries do not permit assisted suicide, Mr Minelli explained.
Each individual pays an initial membership fee, typically around $200 (£133), followed by annual membership fees of $80 (£53). Further fees for the consultation and the assisted suicide itself run to around $7,000 (£4,700).
Some clients, however, are believed to have donated much larger sums.
This is all perfectly legal under Swiss law, as long as Dignitas and Mr Minelli are not making a profit out of it.
But there have been allegations in the Swiss media that Mr Minelli has become a millionaire since he founded Dignitas.
Mr Minelli refuses to discuss the organisation's finances.
"This is a private organisation," he explained. "Only the active members have a right to know the facts, and the public has no right at all. We are not working with public money, so there is no reason for us to answer questions."
The active members are Mr Minelli, and one other who prefers to remain anonymous.
Right to die for all
Mr Minelli and one of the doctors working for Dignitas, Alois Geiger, also defended the organisation's policy of providing services not just to the terminally ill, but to those with chronic illnesses and even mental illnesses such as schizophrenia.
Dr Geiger, for example, provided the prescription for the young British man Dan James, who committed suicide in Switzerland in 2008 after being paralysed in a rugby accident.
"Most people who come to me don't just say 'I want to die'", explained Dr Geiger. "What they say is: 'I don't want to live THIS life anymore.'
"If you have a person who is mentally ill, and it has gone on for years, never getting better, always getting worse, a person who has tried eight times to kill himself, why not give him the possibility to end this horrible life? Schizophrenia is a horrible illness."
Dr Geiger is referring to the case of a 39-year-old Spanish man with paranoid schizophrenia who died two years ago with the help of Dignitas.
The Zurich authorities have now ruled that Dr Geiger, a gynaecologist by training, did not have the required competence to assist his suicide and have removed his power to prescribe for the mentally ill.
Mr Minelli and Dr Geiger are now challenging that decision in court.
Plans to regulate
Meanwhile the Swiss government has put forward two draft papers on assisted suicide, one of which would ban the practice altogether, and a second - the more likely to be approved - which would limit the practice to the terminally ill.
Patients would have to provide evidence from two independent doctors that their illness is incurable and that they are likely to die within months.
They would also need to show that they have made an informed decision, over a period of some time, to end their lives.
All these conditions would effectively end or fundamentally change the practices of Dignitas, whose foreign patients typically arrive in Switzerland, see a Dignitas doctor and die within 24 hours.
"The government has an obligation to protect," explains Margrit Leuthold of Switzerland's national committee on medical ethics.
"So these organisations should have some governance by the state. It cannot be that organisations which deal with the life and death of citizens are just free-acting," she added.
Mrs Leuthold also argues that other countries should pay attention to the debate over assisted suicide in Switzerland.
"We really hope to raise awareness among the countries who send us the most patients, right now that is Germany and Great Britain," Mrs Leuthold said.
"Why do these citizens come to Switzerland? Obviously they have a very strong will to commit suicide, and they have a very strong suffering.
"So I think it's also a call to these countries to deal with this fact themselves, and not just to export the problem," Mrs Leuthold added.
But any change to existing Swiss law is likely to be a long process.
Ludwig Minelli says he will take the government's proposals to a nationwide referendum if necessary.
"I am persuaded that we have to struggle in order to implement the last human right in our societies," he says.
"And the last human right is the right to make a decision on one's own end and the possibility to have this end without risk and without pain."