Maurice Kay QC, appearing for Wayne Darvell, 30, who was convicted with his brother Paul, 31, of the murder in June 1985 of a Swansea woman told the court: 'The police investigation succumbed to the temptation to put forward false evidence to strengthen a weak case.'
South Wales Police had produced 'thoroughly dishonest evidence, constructed upon fraudulently created documents', Mr Kay told Lord Taylor, Mr Justice Swinton Thomas and Mr Justice Judge.
The Darvells were arrested the day after Sandra Phillips, 38, the manageress of a sex shop, was raped and battered to death and were convicted largely on the basis of Wayne Darvell's confession to police implicating his brother. Paul Darvell was sentenced to 20 years, his brother to 15 years.
Mr Kay said the confession was unreliable because Darvell was suggestible and of limited intelligence. Scientific tests had established that interview notes which detectives had sworn as contemporaneous had been made at a later date; the originals had disappeared.
A 153-page statement by a Det Con Jones, said to have been based on the interviews, was written beforehand and was the 'blueprint' for the notes; the statement itself had been 'doctored' and was the result of a process of 'refinement and redrafting.'
Further tests showed that a pocketbook of a Det Con Collins, which he said had been used on the day after the murder, had not in fact been issued until the following August.
Det Chief Supt Don Carsley, then head of South Wales CID had also, alleged Mr Kay, ordered fingerprint officers to stop work on a palmprint in blood found at the murder scene, which they were about to submit for enhancement tests, possibly leading to another suspect. The defence at the trial had only been told that tests had been insufficient for positive identification and not that eight experts had agreed it could not have come from either the defendants or the victim.
He said those in charge were doing their 'utmost to ensure there was no further line of inquiry which would produce evidence inconsistent with their prized confession'. This took on a 'sinister nature' when it became known that, contrary to normal procedure, the photographs and negatives of the palmprint were destroyed before the trial.
Mr Kay also alleged that a Det Con Green planted an earring - similar to that possibly worn by the murder victim - which he said he had discovered in the police car used to take Wayne Darvell to the police station.
The case was referred to the court after an inquiry by Devon and Cornwall police. The Crown Prosecution Service has indicated that the alleged irregularities discovered by the inquiry mean that it will not contest the appeal. The hearing continues today.