The Labour Party is calling for an independent review commission to be set up, as further information comes to light suggesting a possible miscarriage of justice in the Teina Pora case.
Pora has spent 20 years in jail for the murder and rape of Susan Burdett in 1992, a crime he claims he did not commit.
The serial rapist Macolm Rewa was accused of the killing, but not convicted.
Labour's justice spokesperson Andrew Little says information revealed in a TV3 investigation shows police officers had doubts about Pora's responsibility for the crime.
He says in such cases further investigations need to be carried out by an impartial body.
Mr Little says this country needs a standing commission independent of the police, judiciary or Ministry of Justice to look at instances of miscarriage of justice, along the lines of the United Kingdom's criminal cases review commision.
He says work looking into setting up a such a body by the previous Labour-led government needs to be continued to ensure public confidence in the justice system.