The jurors who tried the case of Andrew Adams said their verdict was affected by the 'prejudice and bias' they say was voiced by some of their colleagues. It will be the first time jury members have given evidence on their thoughts about a trial.

Adams, now 36, has served 15 years for murdering a science teacher, Jack Royal, on Tyneside in 1990. Two jurors will testify that they heard other jury members make damaging claims about Adams that had not been given in evidence.

The claims included unsupported statements from unknown sources that the police considered him a 'bad lad' and that he had some connection with the drugs trade. Adams's lawyers will argue that the alleged bias may have been crucial because his co-defendant John Hands - against whom the prosecution case was essentially identical - was acquitted by the same jury.

The strict laws on contempt of court have defeated all previous attempts to make elements of a jury's decision-making part of a criminal appeal. However, it is understood that in this case the alleged bias was not expressed during the jurors' formal deliberations, and can therefore be taken into account.

At the appeal, Adams's junior barrister at his trial, Andrew Menary, now a leading criminal law QC, will give evidence about the way that he and his then leading counsel, John Fordham QC, who has since died, conducted the defence. Fordham and Menary accepted the brief only a week before the trial began, after Adams's previous barristers, James Chadwin QC and Patrick Cosgrove, withdrew because of a conflict of interest. The Observer reported that Adams appeared to be the victim of a miscarriage of justice in 1995, two years before he fought and lost his first appeal. Earlier this year, after his case was reopened by the Criminal Case Review Commission, it was the subject of an investigation in the Observer Magazine

In 1987, three years before his death, Royal had stabbed a man to death after an argument outside a chip shop in his neighbourhood of Sunniside. His victim, David Thompson, was Royal's son's business partner. Royal stood trial twice for murder, claiming that he killed in self-defence. The first jury failed to reach a verdict and the second found him not guilty. From that day on, however, he was said to have lived in fear.

In the evening of 19 March 1990, someone rang his doorbell. When he answered it, he was shot in the face and neck with a shotgun and died almost instantly. Walter Hepple, the first man tried for the murder, seemed to have a motive: the man Royal killed was his sister's boyfriend and the father of their two children. Hepple was acquitted in June 1991, partly because of doubts about the reliability of eyewitness identifications.

Adams, an engineer who worked at his father's aircraft servicing business, was questioned by police and seemed to have a solid alibi. He was convicted on the evidence of Kevin Thompson, a childhood friend of Adams, who was involved in a robbery and later claimed that Adams had killed Royal. There was no forensic evidence against Adams.