A hospital trust has apologised to the families of two patients who were attacked and killed by another patient after his anti-psychotic drugs were stopped.
Ken Godward, 76, and Roger Lamb, 79, died after they were beaten with a walking stick by 70-year-old Harry Bosomworth in St James's University Hospital, in Leeds, in February 2015.
Mr Lamb is reported to have been trying to help Mr Godward when he was fatally injured.
An investigation report leaked to the Health Service Journal (HSJ) details how Mr Bosomworth, who had been treated for paranoid schizophrenia since 1980, was admitted to the hospital suffering from oesophageal cancer.
It explained how a decision was taken to stop the anti-psychotic drug Olanzapine, despite warnings from the patient's family, by clinicians who were more focused on his complex physical needs than his mental health.
The report said that during the night of February 27 and 28, Mr Bosomworth was given a sedative "with the assistance of security staff as HB was kicking and punching staff when they were caring for his needs".
Later that morning, the report said, "staff discovered HB had assaulted fellow patients RL and KG with his walking stick".
Mr Godward suffered facial injuries and Mr Lamb was found lying on the floor with a fractured neck and leg and both pensioners died later.
Despite concluding that "it has been difficult to identify a single root cause for this incident", the report found there had been a number of contributing factors, including not listening properly to Mr Bosomworth's family and a "lack of assertive, structured, co-ordinated and integrated mental and physical healthcare".
It said: "The decision to stop his Olanzapine was taken from a narrow physical health perspective and without any reference to the impact of stopping the Olanzapine on HB's overall mental health and long-standing schizophrenia."
The report said: "We would suggest that if they had spoken to the family in more detail, they would have obtained a more accurate and comprehensive picture of HB's mental health needs."
It concluded: "The low level of basic knowledge of acute medical staff of the needs of people with comorbid mental health issues in acute hospital settings has been recognised as a national issue and was a contributory factor in this case."
Mr Bosomworth died of his cancer in July 2015, the report said.
Mr Godward's stepson Andrew Dixon told the HSJ: "We feel as though we have been taken for a ride."
Mr Dixon said: "We want something put in place that is going to protect people like Ken."
The report said the ward where the attack happened is a medical ward specialising in diabetes care but "often has a high percentage of older people with a wide range of medical conditions that also present a range of challenging behaviours".
An appendix to the report details more than 40 incidents of violent and aggressive behaviour on the ward between April 2014 and March 2015 including nurses being punched, a patient throwing a table across the room and another slamming a medicine cabinet lid on a staff member's fingers.
Dr Nick Scriven, president of the Society for Acute Medicine, said: "This is a shocking case that has gone unreported since 2015 and it forces us all to look at how and where we treat some of our most vulnerable patients."
He said: "We need a total rethink on how and where we can meet these people's physical and mental needs and trusts must be open and honest in the future around this area and investigate and report this type of incident openly."
Dr Yvette Oade, Chief Medical Officer at Leeds Teaching Hospitals NHS Trust, said: "I would like to reiterate my sincere apologies to all the families involved in this tragic incident. We understand that this has been an extremely difficult and upsetting time for everyone involved and we are sorry that we let these patients down."
Dr Oade said the trust had worked with Leeds and York Partnership Trust to make a "significant number of improvements to how we care for patients with challenging behaviours and mental health needs".