Christchurch mosque shootings
New Zealand officials said they made a mistake by allowing the man accused of killing 51 people at two mosques to send the letter, which was posted on 4chan.
A gunman killed 51 people in March during a mass attack on Christchurch's Muslim community.
The 28-year-old Australian pleaded not guilty to 51 counts of murder in the March 15 shootings at two New Zealand mosques.
A 46-year-old Turkish citizen has died from the wounds he sustained in the shooting at Al Noor Mosque, Prime Minister Jacinda Ardern said.
The judge said 28-year-old Australian Brenton Harrison Tarrant was charged with 50 counts of murder and 39 counts of attempted murder.
After the Christchurch attack, New Zealand faces the question of how to deny the accused shooter a platform to spread hate.
Fraser Anning was censured by the Australian senate for "ugly and divisive" comments made after the Christchurch mosque shootings.