David Bain told a school friend that he could rape a woman and use his paper round as a false alibi, according to secret evidence that was suppressed during his murder trial.
The court suppression has now been lifted.
The jury in the 12-week trial never heard the witness statements of the former Bayfield High School students, as the Court of Appeal ruled that the Crown evidence was too prejudicial against Mr Bain.
Now that Mr Bain has been found not guilty of murder, the Herald can reveal the evidence of Mark Buckley and Gareth Taylor, who say Mr Bain planned a rape of a female jogger while at high school.
In its judgment, the Court of Appeal said that while the words "rape" and "alibi" were not attributed to David Bain by the witnesses, both those words were used by the court for ease of reference because they seemed to capture the essence of what was proposed (at least on the challenged evidence).
The pair told police Mr Bain had a sexual interest in the young woman and told Mr Buckley in 1990 that he could use his paper round to "get away" with the proposed crime.
"Mr Buckley's evidence is that the appellant proposed to free up time for this offending by arriving at the usual times at houses where he would normally see the residents (thus suggesting a normal delivery round) but delivering papers at other houses much earlier than usual," said the Court of Appeal judgment.
Mr Bain did not tell Mr Taylor of the paper-round alibi. But Mr Taylor told his wife, Greer, years later - but before the murders - of the rape conversation with Mr Bain, as she was studying music with him.
Prosecutors wanted the jury to hear Mr Buckley's evidence, as the paper-round alibi tied in with the Crown case, particularly Mr Bain's behaviour of the morning of June 20, 1994.
He said he could not have murdered his family because he was delivering newspapers in his Dunedin neighbourhood.
The Crown case was that Mr Bain planned the murders to make it seem that his father, Robin, killed his mother, Margaret, and his siblings Arawa, Laniet and Stephen, then committed suicide.
Two witnesses gave evidence at the trial to say that Mr Bain delivered the papers 10 minutes early that morning.
Another witness, Kathleen Mitchell, said Mr Bain took unusual measures to ensure that she noticed him on the paper round, in particular opening the gate to her property.
"He had never done this before and there was no need for him to do this," Mrs Mitchell told police.
"The circumstances that morning were Alibi plan kept from jury
unusual and since that day I have often thought about it."
The retrial judge, Justice Graham Panckhurst, originally ruled that the jury could hear the evidence of Mr Buckley, but not Mr Taylor.
Defence lawyer Helen Cull, QC, appealed against the decision to let the jury hear Mr Buckley's evidence. The Crown appealed against the ruling that the evidence of Mr and Mrs Taylor was inadmissible.
The Court of Appeal found that the false-alibi evidence had value, but witness statements that Mr Bain had planned a rape were too prejudicial.
"If the jury learns that [Mr Bain], while at school, was apparently planning the rape of a female jogger, there is a risk that the jury will place more weight on the proposed offending than the proposed use of the alibi," said the Court of Appeal decision.
As well, evidence of a preconceived plan to use the paper round as an alibi was not a key part of the Crown case.
The evidence was ruled inadmissible, and was suppressed until the trial ended yesterday.
Mr and Mrs Taylor were interviewed by police before Mr Bain's first trial.
Mr Buckley did not come forward until after the Privy Council quashed Mr Bain's convictions in 2007 and ordered a retrial.