Long–time David Bain supporter, Joe Karam, says it seems the Parole Board "made a mistake" in allowing the release of a now double-murderer who was part of Bain's wedding party.
Paul Russell Wilson, who changed his name to Paul Pounamu Tainui, was a groomsman for Mr Bain.
Today in the High Court in Christchurch, he pleaded guilty to raping Merivale woman Nicole Marie Tuxford, 27, in April last year, having already admitted to her murder.
The 55-year-old killed another woman on the West Coast in the same way more than two decades ago.
"He never denied guilt for the first murder," Mr Karam told 1 NEWS.
"The Parole Board judged him fit to be released back into society, but it seems they made a mistake."
Nicole's family were in court crying quietly as Tainui admitted to sexually violating her.
"It’s a dreadful tragedy for the victim and the family," Mr Karam said.
The Crown is seeking imprisonment without parole when Tainui is sentenced next month.
Nicole was training to be a counsellor with the Phoenix Light Foundation, they described her as a "lovely, soft, caring young woman," who "just wanted to help people".