A jailhouse informant who claimed David Tamihere confessed to murdering two Swedish backpackers is being sued for perjury.
The private prosecution is being brought by self-styled jailhouse "lawyer" Arthur Taylor, who claims that the informant made direct admissions to him that he had lied at Tamihere's trial.
Charging documents lodged with the court set out nine assertions the witness is alleged to have made on oath or in a sworn affidavit knowing they were untrue.
The attempted prosecution - it requires a judge's approval to proceed - is supported by Mike Kalaugher, a private researcher and author of the first book about the Marlborough Sounds murders, The Marlborough Mystery, for which Scott Watson was convicted.
Mr Kalaugher has researched the use of jailhouse informants in New Zealand and told the Weekend Herald they pop up in the cases that remain troublesome for the public, such as Teina Pora and Arthur Thomas.