Agencies missed opportunities to help a woman with a history of mental health problems who said she was going to harm someone, before stabbing a 13-year-old girl to death in South Yorkshire.
Hannah Bonser was jailed for a minimum of 22 years after being found guilty of murdering Casey Kearney in Elmfield Park, Doncaster, South Yorkshire, on Valentine's Day.
Casey was going to a sleepover at a friend's house when Bonser - a total stranger with a diagnosed personality disorder and a history of cannabis abuse - stabbed her once with a 16cm kitchen knife she had bought earlier.
Bonser, 26, had been in contact with a number of agencies since 1993 when her GP raised concerns that she was being neglected by her parents, today's independent report said.
She was in touch with mental health services in Doncaster from 2002.
In the months before Casey's murder, Bonser was admitted to hospital for a brief period before being discharged, and later went to hospital again after taking an overdose.
In January this year, she was offered crisis accommodation after she contacted mental health services and said she needed to be "locked up".
She was sent home a short time later and discharged from treatment on January 30.
On February 14, Bonser stabbed Casey as she walked through the park before going to a nearby mental health charity and handing over two knives as she confessed to what she had done.
Today's report, commissioned by primary healthcare trust NHS Doncaster, found events in Bonser's life could have been changed if agencies had not missed opportunities.
It said she was "almost invisible" to some services, who often failed tolisten to her concerns. But it made clear that Bonser's own actions led to Casey's murder.
"She told many agencies of her concern that she was going to harm someone. Assessments made by them did not identify a high level of risk of this occurring," the report stated.
The report found a lack of co-ordinated plans and a lead professional meant Bonser received fragmented care, with services ending contact with her at points when she was most vulnerable.
Her voice was often unheard and she felt that people did not listen to her or take her seriously, with professional egos getting in the way of providing the help she needed.
"Throughout her life it appears services failed to listen to her concerns," the report said.
"She was almost invisible to some services."
It added: "Everybody knew a little about (Bonser) but nobody had the full picture."
The report found no evidence that Bonser's mental state had improved enough in January to be discharged from the treatment team but rather that it had deteriorated.
But it added: "It is important to note that it was the actions of (Bonser) that led to the tragic death of (Casey) and that at her trial she was found guilty of murder and not manslaughter as a result of diminished responsibility."
The report made 21 recommendations to services including Doncaster Safeguarding Children's Board, Doncaster Children's Services, the Rethink Mental Illness charity, Rotherham Doncaster and South Humber NHS Foundation Trust, Yorkshire Ambulance Service, the Housing Options service and the M25 housing and support service.
Margaret Kitching, NHS Doncaster's nurse director, said everyone involved in the review would ensure that all the recommendations are fully implemented.
She said: "Casey's death was a terrible tragedy and our hearts go out to her parents, family and friends as today will undoubtedly be another very difficult time for them."