The private investigator who worked on the Teina Pora case says the police's decision to re-try Malcolm Rewa over the murder of Susan Burdett has been a "long time coming".
Rewa was tried twice in 1998 for the Auckland woman's murder.
In both trials the jury was unable to reach a verdict over Ms Burdett's murder in 1992.
Teina Pora was convicted of raping and murdering Ms Burdett when he was 17 and was imprisoned between 1994 and 2014, but maintained his innocence.
After more than 20 years in prison, his convictions were quashed by the Privy Council in March 2015 after concerns were raised about the manner in which his confession was obtained by police.
Tim McKinnel, the private investigator and former police detective who spent years campaigning on behalf of Mr Pora, told 1 NEWS questions had to be asked over Ms Burdett's murder once Mr Pora's convictions were quashed.
"It shows us police are now looking at the evidence around Susan's murder objectively and thoroughly perhaps for the first time in a long time," Mr McKinnel said.
"Teina having his convictions quashed and being found innocent was a really important step for Teina of course but we thought it was an important step for Susan and her family but it wasn't the end.
"For us the end is the police exhausting all lines of inquiry, looking at all of the evidence and making a decision about that evidence and the decision today suggests they are doing that."
Police said today that after Teina Pora's conviction for the murder of Ms Burdett was quashed, the decision to not pursue further prosecution of Mr Rewa was reviewed at police request.
Commissioner of Police, Mike Bush, said today that, "I can confirm that the Solicitor-General has agreed to make an application to the High Court to re-try Mr Rewa.
"The family of Ms Burdett have been advised of this development. Mr Rewa has also been advised."