Last month, the Supreme Court quashed Alan Hall's conviction for the murder of Arthur Easton, who was killed in a violent home invasion in 1985. Photo / Greg Bowker
Investigator Tim McKinnel, who worked on Hall's case, said there were Cabinet guidelines in terms of the amount for compensation.
He said if those guidelines were applied to Hall's "pretty tragic circumstances" and the application was accepted by the Justice Minister, the amount could be the largest in New Zealand history.
In the nearly four decades Hall and his family spent trying to clear his name, his mother sold the family home to fund his defence and died fighting to prove her son's innocence.
The case centres on the violent home invasion and killing of 52-year-old Arthur Easton in his Papakura family home.
Easton and his two teenage sons were attacked in October 1985 by a bayonet-wielding home invader.
Easton was stabbed in his liver during the frenzied attack and died of blood loss after emergency services arrived on the scene.
The murder weapon and a woolly hat were all that was left at the scene by the murderer, who was described to be a Māori man, tall and broad in stature.
Hall, who was yet to be diagnosed with autism spectrum disorder, came to police attention two months later because he owned a bayonet and beanie similar to the ones found at the scene, and was walking in the area at the time of the attack.
Extensive police questioning of Hall ensued and investigator Tim McKinnel said the nature of the questioning, and the vulnerability of a man singled out for being different was problematic.
The description of the attacker and key witness statements from a man who was in the area at the time, were concealed by police, and a jury found Hall guilty of the murder in 1986.
After five appeals, Hall's conviction was quashed in June this year.
In the Supreme Court in Wellington, Chief Justice Helen Winkelmann said it was a trial gone wrong, and that there had been a substantial miscarriage of justice and he should be acquitted.
She said the Crown failed to disclose all evidence, which weakened the defence's case, including statements from witnesses about the ethnicity of a person seen, and evidence about which was the assailant's dominant hand.
The evidence from police interrogation should have been excluded, she said, because they went on for too long, without a lawyer, and at times without any recordkeeping.
Winkelmann said to conclude, it was clear that justice had seriously miscarried - either from extreme incompetence, or a deliberate strategy to achieve a conviction.