Witness C, the man whose evidence helped convict double-murderer David Tamihere, has told a court he was "disgusted" at how his cellmate boasted of the killings.
The identity of Witness C is suppressed, but he was a key witness in the 1990 trial of Tamihere, who was found guilty of killing Swedish tourists Urban Hoglin and Heidi Paakkonen and dumping their bodies at sea.
However, Witness C is now accused of perjury and attempting to pervert the course of justice for his testimony that Tamihere offered him a jailhouse confession.
He said Tamihere told him in prison that he killed the Swedes, but Tamihere has always professed his innocence.
Witness C told the High Court at Auckland today that he met Tamihere in prison during the 1980s.
"We basically lived in the same block together 24-7," he said.
"We started working out together and developed an association. We did other sporting activities together."
Witness C said he never mentioned the murders of the Swedes, but Tamihere began talking about it when he referred to a "big map he had on his wall in the cell, of the whole Coromandel area".
"'The silly buggers were looking in the wrong place', or something to that effect," Witness C claimed Tamihere said.
"He told me he came across the Swedish couple in a Coromandel picnic area."
Witness C said Tamihere told him he took Hoglin "away under the pretence of showing him the Coromandel Peninsula area".
"I think he said at some stage [that] he knocked the guy off. He said at some stage he'd disposed of the body at sea, which I learned later on was not true."
The secret witness also said Tamihere confessed that he'd sexually molested Hoglin and tied him to a tree, before also assaulting Paakkonen.
"All sorts of sexual debauchery you could think of, over a three-day period I think he said.
"I was disgusted. How he could be boasting of such things?"
Tamihere also mentioned that he was nearly caught by a group of trampers, Witness C said.
"He said he almost got caught - sprung, I think was the word he used - some campers had come across the clearing.
"Him and Heidi were sitting on a log. Heidi was terrified but didn't say anything."
Conjecture about Witness C's testimony arose in 1995 when Witness C swore an affidavit stating that he lied and gave false evidence during the High Court trial.
However, he retracted it the following year.
But the case was further debated publicly when Witness C handwrote Tamihere a letter in June 2007 stating the "trial evidence was all false and fabricated by the police anyway".
In his opening address, Witness C's lawyer Adam Simperingham, said the case was "about prison survival".
"[Witness C] stands by what he said when he gave evidence in Mr Tamihere's trial," he told the jury.
In 1995, the year of the affidavit, Witness C claims he and his family were threatened, intimidated and assaulted by prisoners, who described him as a "nark".
The fear of retribution led to Witness C phoning Tamihere's brother, John Tamihere, to eventually write the affidavit and retract his trial evidence, Simperingham said.
"I was assaulted, I was forced to make a phone call to Mr John Tamihere and say that the evidence was a whole lot of rubbish," Witness C told the court.
"It was a difficult situation to be in, it was a dangerous situation to be in.
"I was too busy trying to stay alive - I didn't worry about the contents of the statement," he said.
"There was only one thing on my mind at that particular time, that was keeping myself and my family safe."
Witness C said he was threatened with prison weapons and suffered bruising and a concussion from the assaults. He said he didn't tell John Tamihere about the prison attacks.
Simperingham said his client asked for money from police for his testimony, but it wasn't anywhere near the $100,000 that has been discussed over the years.
"It was rather $500 to help cover the cost of phone calls; [he] didn't receive any money," Simperingham said.
He said Witness C also asked the officer in charge of Operation Stockholm, Detective Inspector John Hughes, to attend his parole hearing, but Witness C's release was denied and he remained behind bars.
"The affidavit was not true, he swore the affidavit for the sole purpose of getting the thugs in prison off his back and threats to his family," Simperingham said.
"What he told the jury in 1990 was essentially what Mr Tamihere had said to him."
Witness C said a July 1996 interview with the late Sir Paul Holmes discussing his testimony was full of falsehoods and part of the story he was forming under "threats and duress".
He also said he wrote but didn't post the 2007 letter to Tamihere, adding he was threatened by the same prisoners as in the mid-1990s.
"'He's a nark and should be killed, what the hell are you doing helping the enemy?'" Witness C said other prisoners thought of him.
Witness C was reluctant to mention in court the names of the prisoners he said were threatening him, out of fear of further retribution.
'Even the highest courts in New Zealand have found him guilty'
Under cross-examination from prosecutor Murray Gibson, Witness C was told to "man up" and confirm his testimony was fabricated.
"Everything I said at that trial was told to me by [Tamihere]," Witness C rebutted.
"[Tamihere] maintains his innocence and has always maintained his evidence," Gibson said.
"A lot of them do," Witness C quipped. "But even the highest courts in New Zealand have found him guilty."
"Guilty on your fabricated evidence, Witness C - nonsense," Gibson replied.
Gibson said the "theme" of Witness C's affidavit was that he was "trying to rectify a wrong".
"The reality is, Witness C, that you lie so glibly and effortlessly, isn't it?" the lawyer said.
Witness C replied: "In certain respects I feel sorry for you guys. You got dropped in the deep end on this by another prisoner [Arthur Taylor]."
Tamihere served 20 years for the murders and was eventually released in 2010.
Hoglin's remains were discovered by pig hunters in 1991 in bush near Whangamata, about 70km from where the murders were alleged to have taken place.
Paakkonen's remains have never been found.
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 admitted stealing the Swedes' car but denied having met them.