An autistic man wrongfully convicted of rape and jailed for more than two years is still angry despite being awarded more than $350,000 compensation today, his mother says.

Sickness beneficiary Aaron Farmer was found guilty of the rape of a 22-year-old woman in Christchurch after she picked him out from a photo montage in 2005.

His conviction was overturned in 2007 after fresh testing was carried out on DNA found on the victim.

A police detective who told Mr Farmer his DNA had been found on the victim and his clothes matched the description of the offender - when both claims were untrue - was criticised by the courts.

The man still works for the police - though not in his former role as a detective.

Associate Justice Minister Nathan Guy today formally apologised to Mr Farmer and announced he would get $351,575 to compensate him for the trauma and loss he suffered because of his wrongful conviction.

Mr Farmer told One News he would use the money to buy a house and a new motorbike.

Mr Farmer's mother Beverley Farmer told Radio New Zealand that would help the family get their lives back on track.

"The money is important to Aaron because it will give him a chance to get a life together. The apology is important to me because there are still people out there that believe otherwise because they are ignorant and do not understand what happened."

But Ms Farmer said her son was still angry about what happened.

He no longer trusted the police or the legal system, she said.

"I believe the police that were concerned were looking for an answer and they chose Aaron.

"I believe they set out to set him up right from the start - that is what I believe.

She said the conviction of her son tore the family apart.

"It destroyed our lives, it took away all my siblings. It destroyed everything."

Mr Farmer agreed, saying some family members "turned their backs" on him.

He told One News he had full sympathy for the woman he was mistakenly convicted of raping and hoped the perpetrator would be found.

However, police had no new leads on the case, One News said.

Mr Farmer said he still had "a few questions that need to be answered" by the police.

In a statement earlier today, Mr Guy said the Crown accepted a review by Robert Fisher QC showing Mr Farmer was innocent beyond reasonable doubt.

He had taken the treatment Mr Farmer received from police into consideration when deciding on the final compensation figure.

"The payment compensates Mr Farmer for the non-pecuniary losses he suffered as a result of the wrongful conviction and imprisonment. These losses include his loss of liberty, loss of reputation, loss or interruption with family or personal relationships, and mental and emotional harm.

"While the Crown's apology and offer of compensation can never completely make up for the trauma and loss Mr Farmer has suffered, I hope it can go some way in helping him and his family put this very difficult experience behind them."

Mr Guy defended New Zealand's court system as fair and effective "on the whole".

"However, the system is not infallible. When mistakes like this happen, the Government must do its best to put things right. This compensation payment to Mr Farmer shows the Government's commitment to acknowledging and addressing mistakes when they do occur."

Mr Farmer was not eligible under for compensation under Cabinet guidelines because, when quashing his conviction, the Court of Appeal originally ordered a retrial.

However, Government granted him compensation under an "extraordinary circumstances" provision, after a review proved his innocence.

His case was the first in which compensation has been paid under the provision.

The same provision is being sought by the legal team for David Bain - as he is also ineligible for compensation under Cabinet guidelines.

Since 1998, when the Cabinet guidelines were established, there have been four successful applications for compensation for wrongful conviction and imprisonment.

Police: Criticism justified

Police Assistant Commissioner Malcolm Burgess today admitted police made mistakes during the investigation.

"I think we can be justifiably criticised for the interview that was conducted. We have acknowledged there were some inadequacies in the prosecution phase of the inquiry ... in the manner in which the case was put to court."

He said it was not police practice to lie to people being interviewed during an investigation.

The evidence available to police at the time was that Mr Farmer was the likely suspect, Mr Burgess said.

The officer who conducted the interview with Mr Farmer was "moved sideways" within the force.

"I guess if your career aspirations are to be in the investigation field, that career aspiration dried up when he was moved out of the CIB. So to that extent he was (punished)."

Police were yet to decide if they would make an apology to Mr Farmer, Mr Burgess said.

"That is not something we have formally dealt with yet."