Political pressure is mounting for the Government to re-examine the murder and rape conviction of Teina Pora.
The Labour Party, New Zealand First, the Greens, the Maori Party and ACT say it looks like there has been a miscarriage of justice.
Teina Pora was convicted in 1994 of the rape and murder of Auckland woman Susan Burdett.
ACT leader and a former Minister of Police John Banks said on Tuesday he has seen information which proves that Pora should be released from jail.
New Zealand First's Winston Peters says he too has serious concerns about how police handled the investigation.
In a rare move, the Police Association is calling for an inquiry, saying there is sufficient disquiet among senior detectives to warrant one.
However, Justice Minister Judith Collins said on Tuesday that would be inappropriate, as Pora has not yet exhausted all his legal options.
Ms Collins says Pora's legal team plans to appeal to the Privy Council, and it is extremely important that she does not interfere with court processes just to score political points.
However, Labour's justice spokesperson Andrew Little says the case is very serious and goes beyond the mandate of the Privy Council or the Independent Police Conduct Authority.
He says a properly formulated and conducted inquiry is needed to establish the facts and restore the public's confidence.
Police Minister Anne Tolley says she has no concerns about the way police handled the case.