The government has published its response to the inquiry into the death of David "Rocky" Bennett at a secure mental health unit in Norfolk in 1998.
David Bennett spent the last years of his life at the Norvic Clinic
The inquiry said there was "institutional racism" in NHS mental health services.
The government has now pledged to address the inequalities black and ethic minorities have faced in the provision of mental health care.
For 18 years David Bennett, Rocky to family and friends, was in and out of hospitals with mental health problems.
During the last years of his life he was at the Norvic Clinic in Norwich.
On the night he died, according to a draft copy of the report seen by the BBC at the time, Mr Bennett had been racially abused by another patient after a heated argument.
He was ordered to another ward while nothing happened to the man who abused him.
The subsequent independent inquiry into his death heard that Mr Bennett felt he was being unfairly punished.
Mr Bennett then attacked and seriously injured a nurse.
Between four and five nursing staff restrained him face down, sitting on his legs and across his upper torso for almost 25 minutes.
His family was informed of his death by the police the following morning.
His sister Joanna Bennett says she was told by the Norvic Clinic that her brother had developed breathing problems in the night and that he had been sent to the A&E department where he had subsequently died.
She told BBC Radio 4's Today programme at the time: "When I rang the A&E department the staff nurse said to me 'did you realise that there's been a violent incident'?
"That was the first time I realised that Rocky had not just died from a breathing problem that, in fact, he had been restrained by nurses.
Dr Bennett says her brother was treated as a "lesser being" on the night he died.
The BBC has obtained a copy of the draft report of the eventual inquiry into Mr Bennett's death.
It confirms his sister's assertion that there was no record of any action taken as a result of either the assault, or racial abuse, against her brother.
It is scathing of Mr Bennett's treatment as a black man with more than 18 years in the mental health service.
The report says that at times Mr Bennett was treated "as if he was a nuisance who had to be contained."
Nursing staff at the Norvic clinic were criticised for not having someone at Mr Bennett's head as he was being restrained.
The report goes on: "If that had been done we consider that signs of distress would have been detected earlier than they were and that there was a real possibility that this death might never have occurred.
"There is no evidence of deliberate misbehaviour by any of the nurses involved."
The report says "the issue of race was not taken into account" when the decision to move Mr Bennett to another ward was taken.
It continues: "We form the strong impression that on that evening David Bennett was not treated by nurses as if he was capable of being talked to like a rational human being but was treated as if he was a lesser being, to use Dr Bennett's phrase."
Following the publication of the full report, Norfolk Mental Health Care NHS Trust apologised to Mr Bennett's family and friends, adding that it had "not forgotten that this was a tragedy that happened to a real person".