From the article:
Why can we not name the killer?
In New Zealand's court system, the accused and victims can ask to have their name suppressed, which means it becomes illegal to publish it in newspapers, online or anywhere else.
The purpose is to protect people not yet proven guilty - but also to have a fairer trial by ensuring the jury is not prejudiced by media coverage.
Images can also be withheld. When the main suspect in the Christchurch mosque attacks, Brenton Tarrant, appeared in court, the judge ordered the media to blur pictures of his face