Australian man Brenton Tarrant will be charged and prosecuted in New Zealand over the twin Christchurch mosque terror attacks that have killed 50.
"He will certainly face the justice system of New Zealand for the terrorist attack that he has committed here," Prime Minister Jacinda Ardern told reporters.
She also signalled that if convicted, he would serve his sentence in New Zealand.
"That is an area in which I am seeking advice," she said.
"What I can say is that in the cases where we have seen deportation, it is generally at the conclusion of sentence being served."
Tarrant, 28, who was living in Dunedin but is from Grafton, NSW, has been charged with one count of murder.
He remains the only person charged directly over last Friday's shooting massacres.
He will face further charges before he next appears in court on April 5.
He did not apply for bail when he was before the court on Saturday. Ms Ardern said he was being held in a specialist security facility.
Ms Ardern also confirmed she had been emailed the so-called manifesto just minutes before the attack at 1.42pm on Friday.
"I was one of more than 30 recipients of the manifesto that was mailed out in nine minutes before the attack took place," she said.
"It did not include a location, it did not include specific details. I am advised that within two minutes of its receipt at my office it was conveyed directly to Parliamentary security. "
She said it did not provide details that could have been acted upon immediately.
"Unfortunately, there were no such details in that email."
The NZ cabinet will meet on Monday, where the Christchurch situation will be discussed.
"Gun policy is one of them, but yes, the issue around watch lists and how we can surely give assurances to the public that our agencies have the tools they need, all of that will be on the table tomorrow."
Tarrant was not on any watchlist in Australia or New Zealand.