A friend of Arawa Bain was stopped from testifying that David Bain had intimidated his family with a gun, because the judge was not told of when the alleged conversation had taken place.
Kirsten Koch, who went to a Bayfield High School with Arawa Bain, was a Crown witness in the three-month trial that acquitted Mr Bain of the murder of his five family members.
However, the jury did not hear her entire statement.
Helen Cull, QC, who was on Mr Bain's defence team, objected to the final three sentences of her evidence, which stated: "Arawa had said that the accused had a gun. Arawa told me that he had the gun to shoot rabbits at Taieri. But she also said that it made the family feel scared."
In his written decision of September 2008, Justice Graham Panckhurst said he found it hard to place the three disputed lines in a "meaningful context". Ms Koch and Arawa Bain had drifted apart after school but the friendship had been rekindled in 1994, he said. Ms Koch last saw Arawa at the Bains' Every St home about two months before the family were killed.
"However, it is not apparent from the witness statement when the conversation concerning David's gun occurred," said Justice Panckhurst.
Given this, he said, the conversation was unfairly prejudicial to Mr Bain and the jury could not hear the final part of Ms Koch's evidence.
Ms Koch told the TVNZ Sunday programme that the conversation with Arawa Bain happened in the Every St home a few months before the family were found dead.
"She [Arawa] said the family was scared because David was intimidating them with the gun," said Ms Koch.
Sunday also interviewed two former friends of Mr Bain, Mark Buckley and Gareth Taylor, who told police that Mr Bain planned what a court later referred to as a rape of a female jogger while at Bayfield High.
Bain supporter Joe Karam has dismissed the evidence of both men as nothing more than "fantasy".
The men claimed Mr Bain had a sexual interest in the young woman and had told Mr Buckley in 1990 that he could use his paper round to "get away" with the proposed crime.
Justice Panckhurst said the evidence of Mr Buckley was "quite striking" when viewed in the context of Mr Bain's defence that he was on his paper run when his family were killed.
The Court of Appeal later ordered the evidence was too prejudicial to his defence. In its judgment, the Appeal Court said the words "rape" and "alibi" were not attributed to David Bain by the witnesses; the court had used both words for ease of reference.
Mr Buckley told Sunday that he believed his evidence of a paper round alibi was relevant to the murder trial.
"The jury had the right to hear that because a big part of his defence was: 'I couldn't be at home doing that, because I was on my paper run'."