David Bain shares a smile after learning of the not guilty verdict. Photo / Getty Images
The police need to review their "serious mishandling" of the David Bain case over the past 15 years, Green Party police spokesman Keith Locke says.
Mr Bain was found guilty of murdering his parents and three siblings in June 1994.
His convictions were later quashed by the Privy Council and
on Friday, a jury found the 37-year-old not guilty of all charges at the High Court in Christchurch.
Mr Locke said the police had a case of "tunnel vision" in their investigation of the murders.
"Successive police officers were unable to admit that they were on the wrong track, as ever more evidence of David Bain's innocence came to light," he said.
"They should now question why they recommended a second trial, which forced David Bain to relive the horror of the 1994 murders, as well as being hugely expensive."
Meanwhile, the Dunedin coroner has said he might take another look at the family's deaths, given Mr Bain's acquittal.
Chief coroner Neil MacLean said the implication of the verdict was that Robin Bain killed his family, then committed suicide, Radio New Zealand reported.
As a result, existing death certificates might be incorrect.
Dunedin coroner David Crerar said he was already considering whether to hold inquests into all five deaths.
Judge MacLean and lawyers say a coroner's inquest would not necessarily reach the same conclusions as the trial jury.
- NZPA
