A university professor whose expertise is anaesthesia has cast doubt on the conviction of a man hanged for the double murder of police in the 1950s.
Alfred Moore was sentenced to death after Det Insp Duncan Fraser was shot dead and PC Arthur Jagger fatally wounded near Huddersfield in July 1951.
Professor Philip Hopkins of the University of Leeds said a victim's post-operative statement was flawed.
The Criminal Cases Review Commission (CCRC) said it will not refer the case.
Prof Hopkins' new evidence was passed to the CCRC, but in a statement it said: "We have been unable to identify new evidence that is capable of raising a real possibility that the Court of Appeal would quash the conviction."
In June MP Barry Sheerman said he would raise the matter with Justice secretary Ken Clarke.
And Steven Lawson, a former detective, said in 2009 he believed Moore was wrongly hanged.
The case revolves around events after 10 police officers surrounded Moore's farmhouse in Kirkheaton near Huddersfield.
The police arrived on a Saturday night on suspicion Moore may have been involved in a burglary.
Officers lay in wait around the farm when, in the early hours of Sunday, shots rang out and two officers were found to have been hit.
Det Insp Fraser, 45, died in the attack and PC Jagger, 42, was seriously injured and taken to Huddersfield Royal Infirmary.
Moore was arrested at his farmhouse later and a dying PC Jagger picked him out as the gunman from a nine-man identity parade.
Now Prof Hopkins has told BBC Yorkshire and Lincolnshire's Inside Out programme that PC Jagger would have been in no fit state to give accurate of reliable evidence.
He said: "If I had been his doctor and advising the police and the magistrates, I would have said don't even contemplate using this evidence in court."
In his hospital bed, PC Jagger identified Moore as the murderer and made a written statement just over 12 hours after being shot.
Prof Hopkins found the dying police officer had been given ether-based anaesthetics, two doses of morphine, and was bleeding to death from internal injuries which surgeons had failed to spot during an earlier operation.
He said: "This combination really does raise into serious doubt the ability for PC Jagger to make an accurate and reliable statement or to give an accurate or reliable opinion on the identification of an individual presented to him."
He said PC Jagger was in "a potentially acute state of confusion" and could have been very persuadable by information presented to him by others.
"I think it's very distressing," said Prof Hopkins. "I hope there is a thorough review of the evidence through appropriate process."
Inside Out is to be broadcast at 1930 GMT on Monday, 12 December on BBC One in Yorkshire and Lincolnshire.