A long wait for a convicted murderer will be over tonight.

The Privy Council is to release its decision on the appeal of Teina Pora - who spent 20 years in prison for the 1992 murder of Susan Burdett in south Auckland.

Pora's been found guilty of Susan Burdett's murder twice - in 1994 and 2000.

In both cases, the Crown relied on a videotaped interview, in which Pora admitted to Ms Burdett's murder.

But his defence told the Privy Council in November, that he had the mental capacity of a young child when he made the confessions.

The Privy Council could quash the conviction, order a retrial, refer to the Court of Appeal, or dismiss the appeal.

It'll release its decision at 10 tonight.