Four police officers were guilty of the "most serious neglect of duty" over the death of ex-paratrooper Christopher Alder in 1998, a watchdog has ruled.
Mr Alder, a Falklands veteran, died on 1 April 1998
Mr Alder, 37, who was black, died while lying face down and unconscious in a pool of blood in a police custody suite in Hull, as a group of officers stood chatting nearby.
The police watchdog said the officers had been guilty of "unwitting racism".
Humberside Chief Constable Tim Hollis apologised following the Independent Police Complaints Commission's report.
But Humberside Police Federation says the officers "strongly dispute" it.
Mr Alder's sister said those responsible had still not been held to account. She is calling for a public inquiry.
Five officers were cleared of manslaughter and misconduct in 2002 over Mr Alder's death.
Of the five, one was involved to a lesser extent than the other four in the events surrounding the death, the IPCC report said.
Mr Alder, a father-of-two and a Falklands veteran, was injured during a scuffle outside a Hull city centre hotel and taken to Hull Royal Infirmary for treatment.
He was later arrested for an alleged breach of the peace and taken to Queens Gardens police station.
He lay on the floor of the police station, without moving, for 11 minutes with his trousers round his ankles.
CCTV footage showed officers laughing and joking as Mr Alder lay dying. It was more than 10 minutes before officers realised the seriousness of the situation and went to his aid.
An inquest jury later concluded Mr Alder was unlawfully killed and that he died because his ability to breathe was affected by lying face down on the floor. Medical experts who considered the case were unable to reach a conclusion on a single cause of death.
In a 400-page report published on Monday, Independent Police Complaints Commission chairman Nick Hardwick described the behaviour of the officers present at the time as "disgraceful".
The four officers criticised were Pc Matthew Barr, Pc Neil Blakey, Pc Nigel Dawson and Sergeant John Dunn.
A fifth officer, Acting Police Sergeant Mark Ellerington, was also involved but to a lesser extent than the others, the report said.
In 2004 it emerged that all but Pc Blakey had since retired on medical grounds.
Mr Hardwick said: "I believe the failure of the police officers concerned to assist Mr Alder effectively on the night he died were largely due to assumptions they made about him based on negative racial stereotypes.
"I cannot say for certain that Mr Alder would have been treated more appropriately had he been white - but I do believe the fact he was black stacked the odds more heavily against him."
Mr Hardwick said that although there were "serious failings" by the four police officers, they did not assault Mr Alder and that it could not be said "with certainty" they had caused his death.
But their "neglect" undoubtedly did deny him the chance of life, he said.
Humberside Police Federation spokesman John Savage said the officers denied they had neglected their duties or acted in a racist manner, "unwitting or otherwise".
The officers were cleared of manslaughter and misconduct by a crown court in 2002 and cleared of misconduct at an independent disciplinary tribunal in June 2003, he said.
No concerns had been raised about racism in those cases and the men found it "very surprising that the IPCC has sought to do so now", he added.
Chief Constable Tim Hollis, who was not with the force at the time of Mr Alder's death, said: "The time is...right for me publicly to apologise to Christopher Alder's family for our failure to treat Christopher with sufficient compassion and to the desired standard that night.
"The failure of the officers to explain to the IPCC their actions, including noises recorded on the video before and after Christopher's arrival in the custody suite, appears to have contributed to the IPCC view regarding unwitting racism."
Mr Hollis' apology was dismissed as "far from sufficient" by Mr Alder's sister Janet, who called for prosecutions.
"There are people responsible and they have not been held accountable," she said.