Two million dollars would be a slap in the face for Teina Pora considering the time he spent in jail and the young years he has lost, a law and social sciences professor says.

"I'd start at $6 million and look up," Professor Chris Gallavin, of Massey University's College of Humanities and Social Sciences, told the Herald.

It has been reported that the figure, announced later today, may be around $2 million.

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"An amount of about $2 million would be out of kilter with compensation in Canada and other countries. But let's see what they [the Government] say," Professor Gallavin, formerly dean of law at Canterbury University, said.

Mr Pora was arrested when he was 16 and spent more than 21 years in jail. He is now 40 years old. He has missed out on the chance to add to his family - he has a daughter born months before he was charged with the rape and murder of Susan Burdett - and the likelihood of marriage as well as lost income.

It is understood a trust, with Mr Pora as the beneficiary, will receive the payment.

Mr Pora has told the Herald he wants to travel, to visit a bishop he met in prison who now lives near Chicago and who he credits with changing his outlook on life, and to have fun after so long in prison. His priorities were his daughter Channelle and grandson Benson.

A payment of $2 million would surpass the dollar amount of $950,000 paid to Arthur Thomas in 1980 for his wrongful conviction for the murders of Jeanette and Harvey Crewe but fall short of the figure when inflation is taken in to account.

Mr Thomas' payment is equivalent to $4.63 million today, according to the Reserve Bank's inflation calculator.

Mr Thomas spent nine years in jail having been twice found guilty of the murders. He was pardoned in 1979.

Mr Pora was twice convicted of the 1992 rape and murder of Ms Burdett. The Privy Council last year quashed his convictions and ordered that he should not be retried.

Malcolm Rewa was convicted of sex attacks on 25 women including the rape of Ms Burdett. But two juries couldn't agree whether he murdered her. After the second hung jury, the Solicitor-General stayed a third prosecution. Rewa will be eligible for parole in 2018.

Justice Hansen was appointed in June 2015 to conduct an inquiry into Mr Pora's claim for compensation.

"Mr Hansen's distinguished legal career makes him well placed to consider the claim objectively," said Justice Minister Amy Adams on the announcement of the appointment.

Other recent payments for wrongful convictions include:

David Dougherty: $800,000 paid in 1997 after new DNA evidence ruled him out as the offender for a 1993 abduction and the rape of an 11-year-old girl. He served 3 years in prison. Nicholas Reekie was later convicted of the crime.