The Royal Commission of Inquiry into the attack on Christchurch mosques is inviting the public to make submissions.
The inquiry is tasked with investigating what was known about the shooter before the day of the attacks on15 March, which led to the deaths of 51 people.
It's also investigating whether anything could have been done to prevent the shootings, and if anything should be done to prevent such attacks in the future.
Its chair, Sir William Young, said the public could play a role in helping the inquiry to consider what was known - if anything - about the attacker.
He said submissions were open to anyone with relevant information.
"The public can play an important role in helping the Royal Commission with its inquiries and we welcome submissions from individuals, groups and organisations that can assist us in our work," Sir William said.
"The submission process is open to anyone with information relevant to our inquiry.
"We want to hear from Muslim communities, organisations and individuals about their experiences that relate to [the scope of the inquiry].
"In addition to the written submissions process, a range of other engagement methods will be used by the Royal Commission to connect with New Zealand's Muslim communities, including the affected families, on their terms.
"We know there may be communities in New Zealand who, perhaps due to their whakapapa, ethnicity, religion, interests or activities, have experiences they could share which may be helpful to our inquiry."
The public can submit from Monday until the end of July.