The events preceding the LynnMall stabbings will be investigated by three agencies in a coordinated formal review.
The way Ahamed Aathill Mohamed Samsudeen was managed in custody and in the seven weeks leading up to the attack will be examined by the Independent Police Conduct Authority (IPCA), Office of the Inspectorate at the Department of Corrections, and Inspector-General of Intelligence and Security.
They will ask if the police, Department of Corrections and New Zealand Security Intelligence Service (NZSIS) did enough to assess the risk that Samsudeen posed - and if they did enough to respond to that risk.
The review will look at how the agencies worked collectively and separately, but it will not look at what happened before Samsudeen's most recent time in custody, nor any immigration-related decisions.
Meanwhile, the police and the IPCA are already undertaking a separate review into the decision to shoot Samsudeen.
The coordinated review is due for completion next March, when a public report will be made available.
In a written statement, the Department of Corrections National Commissioner, Rachel Leota welcomed the investigation.
"We, as have others, have been asking ourselves what more we could have done to prevent this tragic attack from occurring, and we are committed to working with the review team to ensure any material that is requested is made available to assist them.
"On behalf of Corrections, I would again like to acknowledge the victims of the attack. Our thoughts are with them as they continue to recover."
The police declined to comment, but earlier this week they released statements from five victims of the attack.
An eighth victim has also been identified - a man who tried to stop the terrorist attacking a woman - and was tackled in the process.
Six people were directly stabbed in the attack in Countdown on 3 September, another one person injured.
Samsudeen, a 32-year-old refugee originally from Sri Lanka, was shot dead by undercover police within 90 seconds of launching the attack.
He had been under 24/7 surveillance since his release from prison seven weeks earlier, because he was deemed a terrorist threat.