Investigators in Britain say a doctor who admitted shortening the lives of nearly 20 patients - including his own son - may yet face charges.
Howard Martin, 75, was cleared in 2005 of murdering three patients with fatal doses of painkiller.
But he has since had his licence revoked and now a dramatic confession to a national newspaper has prompted the police and prosecutors to consider reopening the case against him.
Dr Martin, whose videotaped confession was carried in Saturday's Daily Telegraph newspaper, said he had no regrets, claiming he acted out of "Christian compassion" to end the suffering of pain-stricken patients.
A 2005 reform to the English legal system means the principle that prevented people being tried twice for the same crime, known as "double jeopardy", no longer applies.
Defendants may be tried twice for the same crime if new and compelling evidence is brought to bear.