The Solicitor-General has launched an investigation into the role of all the Crown lawyers ever involved in the case of Alan Hall.
Mr Hall was found guilty of murdering Arthur Easton during a violent home invasion 35 years ago, but the Supreme Court yesterday quashed his conviction.
The Supreme Court found police had unfairly obtained statements from Mr Hall, and failed to disclose evidence such as witnesses' descriptions of the killer as Māori, which Mr Hall is not.
Investigator Tim McKinnel worked on the case, discovering evidence that lead to yesterday's conviction being quashed.
He says evidence has been known for 30 years and there are many questions that must be answered.