Police have not been forthcoming with information which could help exonerate a man who was convicted over a notorious killing, his lawyer says.

Teina Pora has spent 20 years in prison on a life sentence for the rape and murder of Susan Burdett in her Papatoetoe home in 1992.

The case stirred controversy when DNA testing linked serial rapist Malcolm Rewa to semen in Ms Burdett's body.

The Court of Appeal ordered a retrial, and Pora was convicted for a second time in 2000.


Questions have continued to be raised since then, including allegations that witnesses were paid.

A report on TV3's current affairs show 3rd Degree last night suggested a misguided tip-off from Pora's family led to his arrest. The report said Pora was not a party to Ms Burdett's rape or murder, and he was not there at a time.

Pora is seeking a Royal Prerogative of Mercy from the Governor-General, who can order a new trial.

Assistant Police Commissioner in charge of investigations, Malcolm Burgess, said he would not discuss the merits of the case while that process was pending.

But in a statement, he said the evidence against Pora had been heard by two juries - at the original trial in 1994 and at the 2000 retrial.

"Both juries were satisfied that the evidence established, beyond reasonable doubt, that Mr Pora was guilty. He was convicted on both occasions."

Mr Burgess said police would continue to cooperate fully with any lawful requests made for information in relation to the case.

He said a large amount of information had been provided to Pora and his advisers since 2010, in addition to the original disclosure of Crown evidence at the trials.

Pora's lawyer Jonathan Krebs disputed that this morning, saying he had spent many months requesting information but was met with refusals.

"Eventually we had to obtain an injunction from the High Court directing that certain material and certain ongoing materials [be] provided to us," he told Radio New Zealand.

Mr Krebs had received information last night suggesting police had not been complying with the injunction.

"That causes me real concern and I'm going to have to look at what steps I can take to force the hand, because at the end of the day there's a man who's been in custody for 20 years.

"He's still only in his mid to late 30s, and it's simply a gross miscarriage of justice."

The information Mr Krebs is seeking includes fresh DNA evidence. Police were continuing to analyse scene exhibits as they looked for DNA traces.

"We want to see those because we want to exonerate our client, and we can do so via the DNA samples."

Mr Krebs said Pora was convicted by two juries who did not see all the information. Hard and fast evidence would exonerate his client, he said.

The application for a Royal Prerogative of Mercy was filed 18 months ago.