"Let me tell you -- God strike me dead -- what we were trying to do was help the patients. Everything was done with their best interest in mind. First and foremost. Any medicines given were for comfort. If in doing so it hastened their deaths, then that's what happened. But, this was not, 'I'm going to go to the seventh floor and murder some people.'"

However, serious questions have emerged about the grand jury's decision. The case against Dr Pou was originally brought by Louisiana's Attorney General, Charles Foti, and five national experts in forensic medicine, palliative care and medical ethics were told to examine the facts. However, the case was inherited by District Attorney Eddie Jordan. Despite the damning conclusions reached by their study, he did not call them to testify before the grand jury. And because its deliberations are secret, it is not known whether their reports were even seen.

Prominent bioethicist Arthur Caplan, of the University of Pennsylvania, was scandalised. "In reviewing the facts and opinions, my conclusion is that the deaths of the nine persons at Memorial Medical Center in New Orleans are all cases of active euthanasia," Caplan wrote. "Each person died with massive doses of narcotic drugs in their bodies."

These could hardly have been due to a tragic medical mistake, either. "Accidental overdoses would need to have occurred nine times between 12 noon and 3:30pm, all on one floor, to every patient who was left on the floor," observed Dr John Young, former president of the American Academy of Forensic Sciences. "Again, it is noted that morphine was not ordered for seven of the patients and Versed was not ordered for any. Therefore it seems highly unlikely that nine patients died on the same floor on the same afternoon of accidental overdose."

Organised medicine, however, accepted Dr Pou's version of events unreservedly. The head of the American Medical Association, Dr Edward L. Langston, said that she and others had been "bright lights during New Orleans's darkest hour."

The next phase of the research will involve donor tissue, as bone marrow in older patients with heart disease is "not the best", said cardiologist Suku Thambar.

However, when they began to go through the woman's effects after the funeral, they discovered literature from the Final Exit Network, a receipt for the purchase of two helium tanks, and some mysterious messages on her answering machine. Police eventually traced the calls to a retired college professor who was an "exit guide". Under questioning he admitted that he and another guide had helped Jana die by breathing helium.

A special feature on the incident in the Phoenix newspaper New Times points out that Final Exit literature stipulates that anyone who requests its help must be mentally competent and not be opposed by close family members. However, in this case, Jana was clearly psychotic and had instructed the exit guides not to contact her family.

One of the guides told New Times that Jana was not mentally ill, but rather "in the throes of what we call existential suffering", in which "just being alive is a burden". A miserable life is reason enough for Final Exit to offer its services. It describes itself as "the only organisation in the United States willing to help individuals who are not 'terminally ill' -- six months or less to live -- hasten their deaths."

Mr Linden says that he donated sperm in 1977 and five births resulted. He recently contacted two of the children, but has resigned himself to never meeting the other three. Iit is a bitter pill for him to swallow. He writes:

"To the parents, whether they would wish it or not, and whether they disclose to their child or not, the child will always be the donor's child. He is the father of that child. This is an inescapable biological fact and the fundamental reason why the continuing practice of donor insemination is a tragic if not a criminal mistake."

A more full-blooded experiment took place in the violent game World of Warcraft. A deadly virus dubbed Corrupted Blood left millions of corpses strewn over the virtual landscape. Characters fled the scene, taking the disease with them.

A recent article in the leading journal Science highlighted games' "great potential as sites for research in the social, behavioural, and economic sciences, as well as in human-centred computer science". In the past, many experiments used to be done without seeking the consent of participants, but "those days are gone," says author William Sims Bainbridge. But now scientists might be able to use on-line worlds to understand how humans react in crises.

"If we cured all disease - cardiovascular disease, stroke, diabetes, etc. - we would only prolong life on average by 12 years," he said. "So we have pretty much reached the ceiling of what we can do by treating and preventing disease... The next frontier is enhancing life through medical intervention to make people brighter, stronger and healthier."