Three patients who killed three men in separate attacks were all being treated by the same mental health partnership, reports said today.
The men were all convicted of separate homicides committed in 2008 in Bristol, North Somerset and Wiltshire while receiving care from Avon and Wiltshire Mental Health Partnership NHS Trust.
The three independent reports each identified "no direct causal factors" between the care and treatment the three men received and the killings.
James Allen was convicted of murdering his neighbour Terry Hall during a row over a discarded washing machine.
Liam Churchley was jailed alongside his mother, brother and cousins for the savage killing of Alan Riddock outside a pub, while James Bible was detained indefinitely for stabbing his friend to death.
All three had been receiving treatment for a variety of problems, including drug and alcohol addiction and psychiatric disorders.
While the reports highlighted aspects of care that could have been better, each report concluded that it would "not be reasonable" to conclude that these had an impact on each incident.
A total of 28 recommendations are made in the separate reports, of which 22 relate to the Avon and Wiltshire Mental Health Partnership NHS Trust.
Dr Arden Tomison, medical director for the trust, said: "On behalf of the Trust I would like to offer again our condolences to the families and friends of all the victims and to those who have been affected.
"The investigation reports acknowledge the considerable efforts made by our staff to support each service user in the years leading up to the incidents.
"Across the Trust our staff deal with individuals whose complex needs, behaviour and reluctance to be helped can make delivering effective care support very difficult.
"The decisions our staff make about the care and support provided to service users are informed by the best clinical understanding of their individual clinical needs.
"I would like to thank all our staff for their dedication and commitment in supporting people under our care and reassure people that the risk of any act of violence being carried out by a person with mental health needs is very small.
"We also note the investigation teams' endorsement of the internal investigations undertaken by the Trust after each incident and their support for the actions identified to improve ongoing patient care which we have already implemented.
"As the independent investigations highlight, aspects of the way we worked in 2008 could have been better - for example in the way we engaged with families, in collaborative working, in risk management, in sharing information and in care planning - and these are handled very differently today.
"But the investigation teams acknowledge that even if different approaches had been followed, it is not reasonable to assume that the outcomes would have been different."
The findings of the three reports were considered in turn at a meeting of the NHS South of England's patient and care standards sub-committee.
The families of all three victims and their respective killers were invited to attend but only the relatives of Mr Hall attended.
Deborah Hall, Mr Hall's partner of 18 years, said afterwards in a statement: "Terry died unnecessarily. Terry does matter and we have waited nearly five years for some answers.
"This whole process had had a big impact upon the family and we feel it is too easy for the victims to be forgotten.
"We hope that this report goes some way in protecting innocent people in future."