FIVE police officers accused of the manslaughter of a former soldier were acquitted after a judge said conflicting medical evidence meant a jury could not be sure how he died.

Mr Justice Roderick Evans ordered the jury at Teesside Crown Court to clear the defendants of killing Christopher Alder, whose sister Janet lives in Manchester Road, Burnley, at Queen's Gardens police station in Hull on April 1, 1998.

The jury were told by the prosecution that the officers stood around chatting as Mr Alder lay on the floor after being arrested for an alleged breach of the peace.

He had been arrested after becoming aggressive and abusive at Hull Royal Infirmary, where he was taken after being assaulted outside a city centre hotel.

But more than three months into the trial, the jury was instructed to acquit officers Neil Blakey, 42, John Dunn, 40, Matthew Barr, 38, Nigel Dawson, 39, and Mark Ellerington, 36, of the manslaughter of Mr Alder.

Mr Justice Roderick Evans also instructed the jury to acquit all the officers of a charge of misconduct in a public office.

He told the jury there was conflicting medical evidence about why Mr Alder became unconscious, and about what killed him.

During a judgment which lasted almost an hour the judge told the jury -- for the first time -- that an inquest into Mr Alder's death had resulted in a verdict of unlawful killing.

The defendants had unsuccessfully tried to challenge that inquest verdict but the judge told them a criminal trial and an inquest were different.

During a four-year battle the family has had to endure a seven week inquest, a High Court challenge and a criminal trial at Teesside Crown Court.

At one point the family held a vigil outside the Home Office in London, to mark what would have been Mr Alder's 32nd birthday and to raise the profile of its campaign.

Humberside Police Federation chairman Stuart Downes said he was delighted with the outcome, and had already applied to senior officers in the force to reinstate the five men, who have been suspended since Mr Alder died more than four years ago.