A secret jailhouse witness, guilty of perjury at one of New Zealand's most infamous murder trials, says his evidence against David Tamihere had "no impact" on the jury.
Roberto Conchie Harris, previously known only as Witness C, is appealing the "manifestly excessive" prison sentence imposed by Justice Christian Whata.
Tamihere, who has always professed his innocence, was sentenced to life imprisonment in December 1990 for the murders of Swedish tourists Urban Hoglin, 23, and Heidi Paakkonen, 21.
His convictions came on the back of circumstantial evidence and the confessional testimonies of three jailhouse informants - known as Witness A, Witness B and Witness C.
Nearly three decades later and after Tamihere was granted parole in 2010, a rare private prosecution against Witness C was brought by "jailhouse lawyer" Arthur Taylor.
Well-known lawyer Murray Gibson, who prosecuted Harris on Taylor's behalf, said the false evidence was "powerful" for Tamihere's jury.
Following a trial in the High Court at Auckland last year, Harris was found guilty on eight perjury charges.
Justice Whata then sentenced him to eight years and seven months' imprisonment and said Harris' lies were a "brazen assault on the foundation of our criminal justice system".
However, in submissions filed with the Court of Appeal yesterday by Harris' lawyer Adam Simperingham and obtained by the Herald, the informant argues his false evidence made no difference to Tamihere's case.
"Although the jury deliberations leading to David Tamihere's convictions will never be known, it is unlikely that [Harris'] evidence played any material role in finding him guilty," the Gisborne-based lawyer said.
The Court of Appeal when dismissing Tamihere's appeal of his convictions in 1992 also said: "We would be surprised if the jury had given much credence to any of the detail in the stories Tamihere was said to have told these witnesses."
Simperingham also said Harris' testimony had "no impact" if the jury had used it to corroborate the identification evidence of trampers John Cassidy and Mel Knauf.
Cassidy and Knauf gave written statements to police in May 1989 about seeing a woman similar in appearance to Paakkonen and a man, whom police claimed was Tamihere.
"The guy was in his early 30s, part Maori, about 5 ft 11 inches, strong build, outdoor type, black hair, clean shaven although he may have had a moustache," Cassidy said.
Cassidy also later identified the mystery man as Tamihere, controversially from just one photo police showed him.
Harris said Tamihere, who also has other violence convictions, including the 1972 manslaughter of Mary Barchamm, confessed to him while they were in a prison cell.
The prison informant was serving time for killing Northland couple Carole Anne Pye and Trevor Martin Crossley when Tamihere was arrested for the Swedes' murders.
Tamihere, Witness C claimed, attacked and sexually assaulted the Swedes before dumping their bodies at sea.
In 1991, Hoglin's remains were discovered by pig hunters in bush near Whangamata, about 70km from where the murders were said to have taken place, while Paakkonen's remains have never been found.
Simperingham added in his submissions that it was also Harris who came forward to detectives, despite allegations of police inducements and bribes.
"Despite the fact [Harris] maintained his innocence throughout his trial, if not for his earlier actions to come forward and recant his evidence, the trial would never have occurred," the lawyer said.
On August 25, 1995, Harris swore an affidavit stating he lied on the stand and said there were "big offerings" if he was interested in becoming a secret witness for the police.
One of the inducements was said to be a cash bribe of $100,000.
In July 1996, Harris stood by his affidavit when interviewed by the late Sir Paul Holmes and said: "They definitely have an innocent man inside".
But just a few weeks later, Harris retracted his affidavit and produced two statements to police claiming his confession came under threats from fellow prisoners.
At last year's trial, Harris was found not guilty of obstructing the course of justice, which pertained to the affidavit.
Simperingham said Harris' motivation to lie remains unclear, but speculated it may have been to get a favourable parole hearing.
The late Detective Inspector John Hughes, the officer in charge of the Swedes' murder investigation, went to one of Harris' parole hearings in support of him but parole was denied.
Hughes was known by those in the criminal world as "the gardener" due to accusations he tampered with or placed evidence.
After Harris was convicted of perjury, Taylor, the Herald and other media organisations argued for the prison snitch to be publicly outed.
When Simperingham abandoned the appeal of the perjury convictions, Harris was revealed in April to be a double murderer, sex offender and fraudster.
Just days after Harris was revealed Witness B was also identified as Stephen Kapa.
Witness A is now the only prison informant of the three snitches not publicly identified.
His exact location and wellbeing is unknown despite speculation the informant may now be overseas, possibly in Fiji, or dead.