The Royal Commission into the Attack on the Christchurch Mosques says it has interviewed the shooter as part of its efforts to provide the public with answers about the tragic shooting.
In March this year, the offender pleaded guilty to 51 charges of murder, 40 charges of attempted murder and a charge of engaging in a terrorist act and was convicted on every count.
Due to the guilty plea, there will be no trial - which has left friends and relatives of those affected with questions.
Royal Commission chair, the Honourable Justice Sir William Young, said much of the material for the investigation has come from police and other agencies but the interview with the offender would "help with some areas of uncertainty".
The government directed the commission to investigate the offender's activities in the lead up to the mosque attacks.
"In addition, the Terms of Reference and the Inquiries Act 2013 require the Royal Commission to observe the principles of natural justice in respect of any person who may be the subject of adverse comment in the Royal Commission's report. That includes the individual," Justice Young said.
Commissioner Jacqui Caine said the interview was done as part of the commission's promise to the public that it would leave no stone unturned.
"This was a carefully considered decision driven by the need to observe natural justice and the ultimate goal of providing answers to the New Zealand public through an authoritative final report."
The interview with the individual was done in private at Auckland Prison, Paremoremo. The content of the interview is strictly confidential at this point, the commission said.
A sentencing date is yet to be set as the courts work through disruptions from the Covid-19 lockdown.