A triple killer was allowed out on day release, leaving him free to murder a Good Samaritan in a decision branded a "catastrophic failure" by the chief inspector of prisons.
Ian McLoughlin stabbed to death Graham Buck, 66, while allowed out from HMP Springhill in Buckinghamshire, where he was serving a 25-year jail term for killing two men he believed were paedophiles.
McLoughlin had travelled to the home of former prisoner and convicted sex offender Francis Cory-Wright in Hertfordshire in July 2013, and filled a pillowcase with cash and family heirlooms in a robbery.
Mr Buck heard his neighbour's screams and went to investigate what was happening, but was dragged inside by McLoughlin, who slashed his throat.
In a report drawn up in January last year but made public today, Nick Hardwick, the chief inspector of prisons, highlighted a catalogue of failings that allowed McLoughlin to be released.
He said: "The decision to release Ian McLoughlin had catastrophic consequences."
In a highly critical report, Mr Hardwick warned that the system for identifying and managing prisoners released on temporary licence (ROTL) are woefully inadequate.
The number of prisoners serving indeterminate sentences, which are handed out to the most dangerous convicts, and allowed out on day release has increased from 38,000 to more than 90,000 between 2008 and 2012.
But Mr Harding said the systems for managing these offenders in open prisons "lack clarity and are insufficiently robust".
He added: "There is a general presumption in favour of granting ROTL. The purpose of individual releases is not clear, and there are insufficient safeguards to manage the risks presented by some higher-risk-of-harm prisoners."
He said protection arrangements "are not routinely reviewed when prisoners transfer to open prisons" and "risk assessment processes are inadequate".
A lack of competence and failures to share information are leading to "indefensible releases", he added.