Report says risks posed by Darren Stewart, who had long history of mental illness and violence, were not effectively managed

The risks posed by a man with a personality disorder who tortured and murdered a vulnerable flatmate were not spotted by health professionals, investigators have found.

Darren Stewart moved into Steven Hoskin's flat and was a member of a gant that tormented and humiliated Hoskin before marching him to the top of a viaduct. Hoskin, who had learning difficulties, plunged to his death.

A report on Stewart (pdf), who is serving life for Hoskin's murder, revealed that he had a long history of mental illness and violence to others.

It said that in the 11 months leading up to Hoskin's death in St Austell, Cornwall, Stewart was in direct contact or communication with various agencies and services 138 times. These included 81 with health professionals and 42 with police.

But the report says Stewart ? identified in the report as Mr G ? "presented as an emergency" in most of these cases. "In the absence of any over-arching assessment procedure, each presentation appears to have been assessed in isolation," according to the report.

"Most of Mr G's presentations during late 2005 and into 2006 were in 'crisis' mode. No single agency appeared to be aware of the overall extent of his demands on statutory services. The involved agencies did not seek or implement a multi-agency process."

As a result, the information that each party had on Stewart, who was 29 at the time of the killing, was incomplete, the report says.

Published by the NHS South of England, the report says there were "several missed opportunities" to provide a "more systematic and organised approach to Mr G's care and treatment".

"Given the risks identified at regular intervals, it is conceivable that a continued targeting of those more vulnerable than himself might have been predicted.

"The risks posed by Mr G were not effectively managed. Clinical teams and agencies involved in his care did not work together consistently over the years to share information and jointly manage his risks."

But it also stresses that it had no evidence that the murder of Hoskin, which took place in 2006, was preventable.

Philip Confue, chief executive of Cornwall Partnership NHS Foundation Trust, said it accepted the report and findings: "We are sorry opportunities to provide better care and treatment were not taken. A number of improvements have been put in place and today, services are totally different from those available in 2006."

A second report published by NHS South of England focused on the treatment given to Michael Pedder (pdf), who kicked and punched his stepfather, Brian Marsh, to death in Swindon, Wiltshire, in May 2007. Pedder, identified in the report as Mr B, was convicted of manslaughter on the grounds of diminished responsibility.

The report reveals that the community mental health team (CMHT) had not recognised that Pedder, who had obsessive compulsive disorder, could be a danger to those around him, especially his family.

It says: "Mr B had been assessed by the CMHT as being able to manage his OCD symptoms adequately as a consequence of which the CMHT manager and care co-ordinator were in the process of discharging him from the service.

"It is noteworthy that the consultant psychiatrist responsible for Mr B's treatment reported that he was unaware of these plans and would have been concerned about such a decision."

The report notes "an overriding inadequacy by the [CMHT] to appreciate the complexity of Mr B's care and treatment needs".

Marsh's killing was one of four carried out by people known to mental health workers in Swindon within five months.

Laura McMurtrie, chief executive of Avon and Wiltshire Mental Health Partnership NHS Trust, said: "I would like to offer my sincere apologies for the unsatisfactory care highlighted in these reports and our failure to respond to opportunities to provide more effective support. Services have changed significantly since these incidents."