Three of the six men rushed into intensive care when a drugs trial went wrong have been removed from organ support as they make "encouraging progress" towards a recovery.
But two of the men injected with the drug TGN1412, Ryan Wilson and Mohamed Abdalla, both aged 28, remain sedated in a critical condition as Scotland Yard liaises with the Medicines and Health Regulatory Agency while they investigate the trial.
Nick Whybrew, aged 29, a restaurant manager who was given a placebo during the test, revealed that he was questioned by detectives for two hours about the trial. "A detective told me ... they were looking at possible negligence. I don't know what is going to happen if one or more of the boys die, it might even lead to manslaughter charges," he told the Sunday Mirror.
Reports yesterday suggested the drug caused the lymph nodes in monkeys' necks to swell during tests. The manufacturer, TeGenero, ordered doctors to react immediately if they noticed swelling in human volunteers. TeGenero had previously said that there had been "no drug-related adverse effects" during animal trials.
But Professor Johannes Loewer, president of the Paul Ehlich Institute, told The Mail on Sunday: " There were adverse effects in a certain dosage. Some of the monkeys developed an increase in the lymph nodes."
Dr Ganesh Suntharalingam, clinical director of intensive care at Northwick Park Hospital in north-west London, said yesterday: "Two men are still in a critical condition. We are seeing some very early signs of improvement. But they are under sedation for their own comfort."
Friends of Mr Abdalla, still in a coma after his head swelled dramatically, tried to persuade him not to take part in the trial. One friend said: "He laughed off the risk, but I told him no one would offer that much money if they didn't know there was a huge risk. He said he needed the money to pay off debts."