A Broadmoor patient has pleaded guilty to the manslaughter of young mother Rachel Nickell on Wimbledon Common 16 years ago. Convicted sex killer Robert Napper, 42, admitted carrying out the attack which shocked the nation and triggered one of the biggest manhunts in recent police history. Miss Nickell, 23, was stabbed 49 times and sexually assaulted in a frenzied attack after she took her two-year-old son for a walk on the common in south London. Mr Justice Griffiths Williams told Napper he would be held in Broadmoor top security hospital indefinitely. "You are on any view a very dangerous man," the judge said. "You still present a very high risk of sexual homicide which can only be managed in a high security hospital. You must be returned immediately to Broadmoor." Napper was sent to Broadmoor secure hospital for killing Samantha Bissett, 27, and her four-year-old daughter Jazmine in a savage attack in south London in November 1993. He had admitted manslaughter on the grounds of mental illness. He also pleaded guilty to rape and two attempted rapes. Police investigators admit that a series of failings meant Napper was not caught before any of his victims died. Officers failed to question him after his mother rang a local police station in 1989 to say he had confessed to a rape. The officer she spoke to could not match up details of the offence with any rape which had been reported. As a result Napper's DNA was not taken, his house was not searched and he was not arrested. Police admit that it was a missed opportunity which could have saved Miss Nickell and the other victims. Outside court, Commander Simon Foy said: "If it had been followed up Rachel could be alive now." Napper was questioned about a series of sex attacks in 1992 but was wrongly eliminated. Mr Foy added: "These opportunities in 1992 and 1993 were after he killed Rachel. "If all or any of these opportunities had been taken, it is probable that he would have been in custody and would not have murdered Samantha and Jazmine. "We have been absolutely honest about this to their family and we have told them that we deeply regret that this happened and have apologised to them." Police became convinced local loner Colin Stagg was the killer and relied too heavily on a profiler during the inquiry. Mr Stagg, 45, spent 13 months in custody and endured more than a decade of speculation that he was the killer of Miss Nickell. This year, he was awarded £706,000 compensation from the Home Office and the Metropolitan Police have now made a public apology to him.