Witness C was fed his evidence in the David Tamihere double murder trial by a senior police officer, a court has heard.
The man, known only as "Witness C", is accused of perjury and attempting to pervert the course of justice after he testified that Tamihere told him in prison that he'd killed Swedish tourists Urban Hoglin and Heidi Paakkonen and dumped their bodies at sea.
The alleged false testimony came at Tamihere's murder trial some 27 years ago, but Witness C's name and identifying details have been suppressed since.
Tamihere's brother, former Labour Cabinet Minister John Tamihere, was the first witness called to the stand and said it was the first time he's seen Witness C since his sibling's trial.
Five years after Tamihere was convicted of the murders, Witness C swore an affidavit "effectively confirming that he lied and gave false evidence in a High Court murder trial".
John Tamihere, a former broadcaster, said he had helped prepare Witness C's affidavit in 1995 following three phone calls from the jailhouse informant.
"I was somewhat skeptical about the conversation, I was wondering whether there was going to be a bit on the end of it for some inducements," he said.
"The evidence was in effect given to him by a senior police officer, and then went on to talk about the type of inducements that were offered to him," John Tamihere told the court about the affidavit.
John Tamihere added that the legal document accused Detective John Hughes of promising incentives, including a sum of up to $100,000, if he gave false evidence against his brother.
"The people involved in this case were the same people involved in the Arthur Allan Thomas case," John Tamihere said.
He said Witness C's motivation for signing the affidavit was to "bring justice to a case where his evidence had led to a conviction".
"He wanted to alert everybody to the fabrication of evidence."
Having sat through the murder trial, John Tamihere said Witness C's testimony had a "significant impact" on the jury, adding that it allowed the jurors to "link the evidence together".
However, in 1996, Witness C retracted his affidavit.
Witness C has pleaded not guilty to eight counts of perjury and one of attempting to pervert the course of justice.
The case was laid as a private prosecution by Witness C's long-time fellow prison inmate and serial litigator Arthur Taylor, and will be led by lawyer Murray Gibson.
Witness C was one of three jailhouse informants who gave evidence for the Crown during Tamihere's trial.
Tamihere was convicted of the murders and eventually released from prison in 2010 after serving 20 years, but he has always professed his innocence.
Hoglin's remains were later discovered by pig hunters in 1991 in the Wentworth Valley near Whangamata on the East Coast, about 70km from where the murders were alleged to have taken place.
Witness C had claimed Tamihere had also stolen Hoglin's watch and given it to his son, however, the watch was found on the Swede's body.
Paakkonen's remains have never been found.