The spotlight is now turning on the police and lawyers who helped put Hall behind bars.
Police this afternoon released the terms of reference (TOR) for its two internal investigations into the case.
One is a full review of the original police investigation. The other is a more targeted probe to investigate whether officers were responsible for a decision not to include crucial witness statements about the ethnicity of the attacker in court.
The TOR notes that even under trial processes at the time, witnesses' original police statements should have been disclosed to the defence and that it appears a deliberate decision was made to omit the original descriptions of the attacker.
The notes also say that while practices around disclosure were "significantly" different in the 1980s, further material was also not disclosed including statements from the sons of the slain man and an ambulance driver.
Police said the reviews were being done so they could fully understand what happened before determining the next steps.
The first phase of the broader review will be done by the end of September.
The Independent Police Conduct Authority and Solicitor-General are also investigating the case.
Two weeks ago the Solicitor-General released its terms of reference for its probe into the actions of Crown lawyers involved in the case.
RNZ has also asked to see the IPCA's terms of reference for its investigation but the IPCA said it does not normally prepare any.
It said its jurisdiction covers police policy, practice and procedure including the actions of individual officers.
- RNZ
