A top lawyer is predicting an investigation into Crown Law's role in a substantial miscarriage of justice could take months and look at the actions of 10 or more lawyers.
The police have also launched an internal review after the Supreme Court on Wednesday quashed Alan Hall's 1985 murder conviction.
Chief Justice Helen Winkelmann said there was either extreme incompetence, or a deliberate and wrongful strategy to achieve the conviction.
Criminal Bar Association vice president Adam Simperingham said depending on the outcome, serious charges and jail time were possible if convictions eventuated.
Meanwhile a former journalist who made an investigative podcast about the Alan Hall case said he believed there is a credible suspect for the murder.
'A lot of very compelling evidence points to a particular person or people'
Former Newshub journalist and solicitor Mike Wesley-Smith has spoken to many of the key figures involved in the case - including police and lawyers in the prosecution team - and made a podcast about his investigation.
The case is decades old now, but despite that Wesley-Smith believes there was a lot of evidence that pointed to an alternative suspect.
"Which gives me some real hope for any new attempts the police may make to reopen the case.
"Sometimes you have these miscarriage of justice cases where there is no viable alternative suspects, and that leaves a sense of unfinished business.
"But here I do think there is a lot of very compelling evidence that points to a particular person or people."
He said he could not imagine how the past 36 years had been for the Easton family - let alone the past couple of days.
Arthur Easton was killed in the violent home invasion in Auckland.
Wesley-Smith said the statement the family released yesterday was incredibly significant.
"Its clarity and its assertiveness was really striking," Wesley-Smith said.
Stuff reports the Easton family are "shaken and appalled" about the way the conviction was obtained.
"Our family had placed our trust in the criminal justice system, and it has failed both families.
"Our hearts go out to Alan, his late mother and family."
Wesley-Smith said when he first came across the case and heard witness statements had been changed he was floored.
"It was the obviousness of the unfairness of the trial... it was just so obvious I sometimes [had to]... stand back and ask myself 'am I missing anything here? What would possibly explain or have rationalized this approach by the prosecution?'
"And an end, unfortunately, the worst explanation turned out to be the true one."
He commended the Crown's decision not to oppose Hall's latest appeal in 2021, and the relative speed at which the judgement came this week.
He also said he was surprised and pleased by the speed in which the police and the Solicitor General announced their investigations.
QC's investigation could take six months, cover many lawyers and police
The Solicitor-General has asked Nicolette Levy QC to investigate the Crown's role in the miscarriage of justice - and to look into any Crown lawyers involved in the case, from the trial until now.
The Solicitor General's office told RNZ the terms of reference would be released in "a few weeks".
But Criminal Bar Association vice president Adam Simperingham said he estimated it could take about six months for Levy to do her work.
He said she would have access to all of the police files and be able to interview the police officers, the Crown prosecution team - and write up a report.
This could then by used as a basis for referrals for any prosecutions.
Simperingham said there could be about a dozen people that Levy would have to take a close look at in the first instance.
For a case like this there could be five or more detectives involved in the original murder investigation.
There would be many more uniformed constables - although they may not be the subject of Levy's scrutiny.
Then at least two, maybe four lawyers in the prosecution team.
He said each appeal could pull in new prosecution lawyers to work the case, and depending on personnel it could double the number who would need to be scrutinised
There were four appeals.
"There would be just a tonne of work involved," Simperingham said.
"And they should probably want to get it all peer reviewed and... you're dealing with people's lives and careers and reputations.
"I'd say six months, but she might be quicker than that - I'm not too sure."
He said there was no statute of limitations in New Zealand, and age was not a barrier to prosecution of a person was of sound mind.
He said the police and prosecutors work closely together on murder cases, but the prosecutors call the shots - what charges to lay, what witnesses to call. An investigation should reveal what police and prosecutors knew - and when.
He said notwithstanding the investigation needing to be completed and assuming there was a case to answer a likely charge could be of perverting the course of justice, which carried a seven year jail term.
Perverting the course of justice is "doing things in court or outside of court that was done with an intention to alter the outcome of a court proceeding".
"It's considered very, very serious by the courts, it's pretty much the presumption that you'd go to prison for committing the crime of perverting the course of justice.
"The victim of the crime is the justice system itself, so it's dealt with very, very sternly and seriously by the court."
Simperingham said the case had raised fear among his peers about whether there were more examples of cases with similar problems to Hall's which were yet to come to light.
He said if it turned out the case had legs, there was potential the it could all ultimately lead to a Royal Commission of Inquiry looking at other prosecutions.
Simperingham said in his opinion the culture of prosecution had changed in the past few decades, with less of a 'win at all costs' approach.