The secret jailhouse informant, whose identity remains hidden, was one of three prisoners to give evidence at Tamihere's trial for the murders of Swedish tourists Urban Hoglin and Heidi Paakkonen.
However, in a rare and "truly exceptional" case, Witness C was found guilty by a jury in August of eight counts of perjury for fabricating Tamihere's confession.
Despite Witness C's perjury convictions, Tamihere's murder convictions will stand unless he is granted a Crown pardon.
He has already exhausted the judicial appeals process when he was denied leave to appeal to the Privy Council in 1994.
Tamihere, who has other violence convictions, including manslaughter, admitted to stealing the Swedes' car but has always denied having met them, or confessing to their murders.
He was released from prison in 2010 after being sentenced to life imprisonment.
When sentencing Witness C, Justice Whata described the perjury as a "brazen assault on the foundation of our criminal justice system".
The judge also revoked the informant's name suppression which has been ongoing since 1990.
But an interim suppression order was made after Witness C's lawyer Adam Simperingham indicated an appeal to the Court of Appeal against the perjury convictions.