The prisons and probation service has "apologised unreservedly" after a man was freed to commit a series of sex attacks on women and children.
Joseph McCann subjected 11 victims to a horrifying ordeal in a spree of abductions across London and the North West.
Like the London Bridge terrorist Usman Khan, the 34-year-old was on an indeterminate sentence for previous violent offences.
Indeterminate sentences for public protection (IPPs) effectively carry a life licence, requiring a Parole Board assessment before an IPP prisoner is eligible for release.
McCann was released on licence in 2017, which meant he could be sent back to jail if he reoffended or breached his parole conditions.
Later that year, while on licence, he was arrested and charged with a further offence and was given a three-year jail term.
McCann's case should have been referred to the Parole Board before he was released but in February this year he was dealt with as a "determinate sentence" prisoner.
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This meant he was automatically released 18 months into his sentence.
It is understood one Probation Service worker has been demoted as a result of a review of four staff who had direct contact with McCann.
Jo Farrar, the chief executive of HM Prisons and Probation Service, has "apologised unreservedly" for failings which led to McCann's release two months before he launched his spree of sex attacks.
She said: "These were appalling crimes and our thoughts and sympathies are with the victims and their families.
"We recognise that there were failings and we apologise unreservedly for our part in this. We are committed to doing everything we possibly can to learn from this terrible case.
"We have taken strong and immediate action against those involved in the management of McCann's case and are taking significant steps to improve intelligence sharing between agencies.
"At the same time, we are developing new mandatory training on recall for all probation officers and we have updated guidance on the threshold for recalling an offender to prison."
Nick Hardwick, former chair of the Parole Board for England and Wales, had earlier told Sky News he believed McCann should never have been free to commit his crimes.
He said: "This is a very concerning case. It was a dreadful set of offences.
"In this case, there was clearly an individual error. McCann should have been referred to the Parole Board after he committed further offences and I'm very confident in those circumstances that the Parole Board would not have re-released him.
"The new offences were too similar to the previous ones, he wouldn't have been re-released."
Mr Hardwick, who is also a former chief inspector of prisons, said the issue highlights the worrying deterioration of the criminal justice system over recent years.
He said: "I think this is a symptom of a probation system and a court system under huge pressure, which makes individual mistakes more likely.
"It's not that we need tough justice, we need smart justice. We need a whole system approach to tackling this. These are areas that have been neglected by the politicians and now we're reaping the consequences of that.
"The problem with prison and probation is the number of experienced staff that we've lost. Even if you recruit new staff now, which they're doing, they simply don't have the experience of the people they are replacing and that's what creates the dangers."
There are differences between the apparent mix-up that led to McCann's release and the automatic release of terrorist KRead More – Source