CCTV footage of a former paratrooper choking to death while handcuffed and in police custody is to be shown in a BBC documentary.
The footage is described as 'very disturbing'
Christopher Alder, 37, of Hull, died at Queen's Gardens police station in Hull in April 1998.
The father-of-two had been arrested in hospital, where he was being treated for a banged head following a scuffle outside a hotel.
Humberside Police had refused to release the footage.
The video will be shown as Mr Alder's sister Janet, of Burnley, Lancashire, calls for Home Secretary David Blunkett to order a public inquiry into her brother's death.
She supports the programme-makers broadcasting the footage.
"It is an extreme measure, it has not been an easy decision to make but we feel that ordinary people need to know what's gone on," said Ms Alder.
The BBC obtained the video from a source other than the police for the Death on Camera programme, part of the Rough Justice series.
Executive producer Simon Ford said: "We'll be showing an 11-minute film of Christopher dying in the police station.
"The family have been asking for years to have it made public.
"The documentary will feature the real images alongside the reconstruction, which will make it very clear what is happening.
"It's a big deal to be showing pictures of a man dying, especially when the authorities are saying it cannot possibly be released.
"We considered the situation and found it was in the public interest to show the film when we had the footage in our possession.
"The public deserve to be able to make their own minds up about this."
An inquest concluded Mr Alder was unlawfully killed.
He was injured during a fight outside a Hull hotel and went to Hull Royal Infirmary for treatment.
He was arrested after he became aggressive in the hospital.
DEATHS IN CUSTODY 2002-03
104 people died in police custody
16% ethnic minorities
Highest number of deaths in Metropolitan Police area
Mr Alder choked to death on his own blood and vomit as he lay on the floor of the police station, without moving, for 11 minutes.
Sgt John Dunn, 40, and Pcs Neil Blakey, 42, Mark Ellerington, 37, Nigel Dawson, 41, and Matthew Barr, 38, of Humberside Police, were cleared of manslaughter and misconduct after a judge directed a jury to find them all not guilty.
An independent hearing cleared all of them of neglect of duty allegations.
Humberside Police's Deputy Chief Constable Steve Love said: "All of the officers deeply regret the death of Christopher Alder.
"All have faced a criminal trial and a discipline hearing and all have been acquitted of any wrong doing.
"As far as Christopher Alder's family is concerned, Humberside Police acknowledges that there is an absolute need to have face-to-face contact with the family with a view to listening to what has happened to them over the past six years. That is why we have assisted the BBC.
"The BBC has chosen to show the CCTV footage, which was not provided by Humberside Police. We firmly believe that a film which portrays someone dying is not for public viewing.
Mr Love said since the death of Christopher Alder, Humberside Police has introduced "changes which better safeguard the needs of those in custody".
These changes include further training for officers and support staff and "significant improvements" in the provision of custody arrangements."
A spokesman for the Home Office said it was satisfied the case had been investigated thoroughly by the appropriate authorities.
"All deaths in custody are regrettable, but the death of Christopher Alder is particularly tragic because although it followed an assault on him prior to him being detained, the cause of death could not be established."
Death on camera will be shown on BBC One at 2100 BST (2235 BST in Scotland) on Wednesday.