A paranoid schizophrenic stabbed a friend to death after experts repeatedly failed to intervene in his case, a damning report concluded.
Leyton Williams, 39, was released early from a secure hospital to his family home in Cardiff, South Wales, without supervision in 2008.
In June 2009, while hearing voices in his head, he launched a violent attack on his mother, leaving her at home in a pool of blood.
He then walked to the home of friend Anthony Kitley, 39, in Tremorfa, Cardiff, and stabbed him to death with a shard of glass. The attack came after police had raised concerns about his mental health following an earlier series of calls to his family.
Williams was found guilty of manslaughter at Cardiff Crown Court in June 2010. He also admitted causing grievous bodily harm with intent to his mother. He was detained indefinitely at a high-secure unit under the Mental Health Act with special restrictions placed on his discharge.
After the trial last year, Mr Kitley's mother Gale said: "The panel that released Leyton Williams virtually signed my son's death warrant."
The family released a statement welcoming the report's publication and saying they did not blame Mr Williams for their son's death.
They highlighted the initial step to release him early as "this one decision damaged all of our lives irreparably."
The report, compiled by Healthcare Inspectorate Wales, follows a full review of the tragic circumstances surrounding Mr Kitley's death.
The watchdog's findings highlight a "communication breakdown" between health and social-care agencies. It also lists a series of concerns regarding opportunities which, had they been acted on, might have averted a killing.