Prosecutors were forced to drop a manslaughter case against a violent alcoholic after his victim suffered a heavy fall in a hospital ward only hours before his death.

Terrence Russell admitted attacking fellow drunk Keith Cordingley at the shabby Bradford flat they shared, punching and then repeatedly kicking him in the head.

But a Court heard how it was impossible to prove that the assault caused his fatal head injuries rather than the later accident at Bradford Royal Infirmary.

At Bradford Crown Court yesterday, Russell, 40, of Easby Road, admitted a lesser charge of assault occasioning grievous bodily harm on October 5 last year and was jailed for 18 months.

The court heard how Russell attacked Mr Cordingley following an alleged sexual assault on an 11-year-old boy who had stayed in their flat the night before.

Mr Cordingley - who had a previous conviction for a sex offence against a child - staggered bleeding to the nearby Beechfield Hotel where eyewitnesses saw the boy attack him as well while Russell looked on.

Jeremy Richardson, QC, prosecuting, said ambulance staff took Mr Cordingley to Bradford Royal Infirmary where although suffering from head wounds, he was "fully alert and speaking clearly".

Russell and the boy later arrived and sat talking and drinking with Mr Cordingley. But at about midnight, after the 50-year-old had been left alone lying on a treatment table, a nurse heard a loud thump.

When she rushed into the room, Mr Cordingley was laying bare-chested on the floor insisting he was "all right".

The following morning, his condition worsened dramatically and after being transferred to Leeds General Infirmary, he died of a blood clot at about 10.45pm. Both Russell and the boy were initially arrested on suspicion of murder and although charges were dropped against the youngster, Russell was charged with the offence.

As detectives carried out a thorough investigation, medical experts were called to assess Mr Cordingley's fatal injury.

One expert, Professor Michael Bell, said it was most likely it had been caused by the assault, while another, Professor Helen Whitwell said it "may or may not".

Mr Richardson said that the uncertainty meant that Russell could not be tried for murder or manslaughter.

He added: "The Crown has been left in the unsatisfactory position that it has evidence of the defendant's culpability to a civil but not criminal standard.

"It is therefore left with no alternative than to accept the non-homicide plea."

Roger Thomas, QC, for Russell, said: "What clearly must have happened is that unfortunately there must have been an advance from Keith Cordingley to the boy."

He explained that the youngster was the son of Russell's former girlfriend who occasionally ran away from home and stayed at his flat.

Sentencing Russell, the Recorder of Leeds, Judge Norman Jones, QC, told him: "It has not been possible to establish a homicide prosecution against you.

"It may be that you did not cause this man's death but anyone who kicks another man in the head runs the risk of doing that."

And after the case, Detective Superintendent Phil Sedgwick, who led the investigation, said: "It may be that Keith died as a result of the attack or from the fall in the hospital.

"But if he did die from the fall, he would not have been in hospital in the first place if Russell did not attack him."