Fifteen years ago, a judge gave a jury a choice: either Roseanne Catt was "evil and manipulative" or the victim of a monstrous conspiracy.

The jury decided she was evil and found Catt guilty of possessing a revolver and of assaulting, stabbing, attempting to poison and planning a hit on her husband, Taree motor mechanic Barry Catt.

Now an acting District Court judge, Tom Davidson, has found evidence that she may have been falsely convicted on unreliable evidence of Barry Catt and his mates, including NSW detectives.

In the report of his inquiry into the case, released yesterday, Judge Davidson found that a former NSW detective, Peter Thomas, may have planted the gun. And he found evidence that Barry Catt, retired Taree motor mechanic Adrian Newell, Mr Thomas and Detective Carl Paget may have framed Ms Catt on the charge that she spiked her husband's drinks.

Judge Davidson found that while there was evidence to support six other convictions, it was reasonably possible that the jury's verdict in those cases was substantially influenced by the unreliable evidence of Mr Thomas, Mr Newell and Detective Paget.

Catt was given a 12-year jail sentence in 1991 and spent the next 10 years buried in the NSW prison system, always maintaining her innocence.

In 2001, the NSW Attorney General, Bob Debus, received fresh evidence that the gun may have been planted and ordered a new appeal.

Yesterday, the NSW Court of Criminal Appeal received Judge Davidson's fresh findings of fact. It has reserved its decision, but its task now is to decide whether or not Catt is guilty. If it decides to quash one or more of eight convictions, the court will either order a retrial or acquit her.

Yesterday, Crown Prosecutor Wayne Roser argued that the appeal court should reject Judge Davidson's finding.

After the hearing, Catt said: "Judge Davidson's judgement has restored my faith in the judicial system. At last I have had an unbiased hearing. Whatever the heartache, I will never lie down. I believe justice will now be done."

The judge found that Mr Thomas used improper methods of investigation, had a "propensity to use his office to damage Ms Catt ... and demonstrated a lack of objectivity which descended into malice and abuse of power".

He accepted the fresh evidence of Queensland barmaid Gina Hart who gave evidence that, in 1999, Mr Thomas had offered her $10,000 to sign a false statement that her employer had burnt down his pub. He also accepted evidence that in another case in 1991, Mr Thomas had attempted to coerce a woman to give false evidence against her husband afterhe charged them both with a bombing in Byron Bay.

He found that a conversation between Mr Thomas and the woman was "capable of supporting a conclusion adverse to Thomas of complicity in a serious offence" and that a case could be made that Mr Thomas had lied about this conversation during the court case.

He found that Mr Thomas had a "propensity to apply pressure ... in a way calculated to produce false evidence" that raised the possibility that a number of Crown witnesses may have been pressured by Mr Thomas to give false evidence.

Judge Davidson found that as a witness, Barry Catt was "verbose, rambling, and at times irrelevant to the point of incomprehensibility, and that he could not accept his evidence unless supported by other independent and credible witnesses".

The Crown had alleged that as part of her campaign to get rid of her husband, Roseanne Catt had placed large doses of drugs, Lithium and Rivotril, prescribed for Barry Catt's bipolar condition, in the drinks and food in his office.

Judge Davidson found that Mr Newell, who worked closely with Mr Thomas, was so opposed to Roseanne Catt and sympathetic to Barry Catt - who had been charged with sexual abuse - that he may have contaminated the drinks.

Detective Paget gave evidence that he found containers of Lithium and Rivotril in a black handbag in Roseanne Catt's bedroom. Judge Davidson found there was a reasonable possibility that Detective Paget was lying and that he and Mr Thomas concocted this evidence.

It was suspicious that the bag did not appear in police photos of articles seized or in the exhibit book at Taree police station.

Taree resident Graham Fellows gave evidence at the inquiry that while he was working at Barry Catt's business several years ago, Barry Catt had told him he had set Roseanne up for a "big fall" and that they "put some tablets in some milk" and that "what we done it was done so well".

Mr Fellows said he did not like Barry Catt, whom he said was present and gave approval for him to be beaten up in 1999. While finding that his ill-will towards Barry Catt could affect his reliability, Judge Davidson found Mr Fellows's evidence was "sufficiently credible" to be taken into account on whether there has been a miscarriage of justice in the attempted poisoning conviction.

In July this year, Judge Davidson sent evidence of hundreds of phone calls between Mr Thomas, Mr Newell and Barry Catt while they were giving evidence at his inquiry to the Police Commissioner, Ken Moroney, for investigation.

On the day of her arrest in August 1989, police allegedly found a pistol in the ensuite of Roseanne Catt's bedroom. Judge Davidson found Mr Thomas had an opportunity to plant the revolver and that fresh evidence supported that he may have done so.

This fresh evidence came from Peter Caesar, who worked alongside Mr Thomas as a private inquiry agent after Mr Thomas left the police force and moved to Queensland in 1991.

He told the inquiry that Mr Thomas had told him Roseanne Catt was the "lowest form of slut" and he had said on a number of occasions that he had "planted the gun". Mr Thomas's former secretary, Leanne Cheers, gave evidence that after she lodged a claim for sexual harassment against him, Mr Thomas said "he would set me up like he did that bitch".

Judge Davidson found that Barry Catt's previous housekeeper, Marie Whalen, was an unreliable witness and that acceptance of her evidence by the jury "is likely to have had serious adverse repercussions to the case presented on behalf of Ms Catt on all contested issues" at the trial.

After Ms Catt's arrest Ms Whalen told Internal Affairs, a Taree solicitor and two Family and Community Services officers independently that she had been taken to a deserted house by Mr Thomas and Detective Paget. After Detective Paget had pulled out a gun she signed a statement against Roseanne Catt.