The massacre has shocked the world not only because of its scale - the shooter continued his rampage for more than 30 minutes at two mosque before he was arrested - but also for the brazenness in which it was live-streamed on Facebook.
Dozens commented, cheering him on, while others watched horrified as social media giants struggled to prevent the 17-minute video from being downloaded and re-shared over and over again.
He also published a 74-page manifesto ahead of the attacks, sharing it on Twitter and sending to dozens within New Zealand, including Ardern's office and media outlets.
While Tarrant is held in detention ahead of his next court appearance on April 5, he will be denied access to media, including radio, television and newspapers. He is under 24-hour surveillance and will not be allowed visitors.
Ardern declined to say whether his trial will happen behind closed doors, but she emphasised to reporters that New Zealand will deny him the ability to lift his profile through the attacks. In his only court appearance so far, Tarrant's face was blurred out in photographs and the video feeds showing him escorted into the courtroom, which the judge says will protect his right to a fair trial.
Ardern's case for not naming terrorists or focusing on them isn't exactly new.
Some researchers argue that terrorism wouldn't exist without the publicity media grant them by reporting on their actions and ideologies.
On the flip side of this argument, however, some terrorism analysts have maintained that examining and discussing motives as well as individuals' path to radicalisation is crucial to understand how to prevent future attacks.
Democracies in particular, they argue, should have an inherent interest in understanding why some in their midst feel the need to resort to violent means to pursue ideological goals.
Besides that, there just aren't a lot of options to stop people from focusing on suspects, as history shows.
When Germany's left-wing terrorists began kidnapping people across the country in the 1970s, the government introduced a news embargo. In other countries, terrorism suspects were charged in secret trials to avoid publicity and to prevent national-security-relevant details from becoming public. In both cases, however, foreign media outlets - not bound by the same rules - broke embargoes and questioned the government-imposed secrecy.
Ardern was widely applauded for her initiative, including by the husband of late British MP Jo Cox, who was murdered by a right-wing extremist in 2016.
"When Jo was killed I vowed the same," Brendan Cox wrote on Twitter. "I have often genuinely forgotten the person's name and my kids have never heard it. Notoriety is such an important driver for terrorists and we should all get better at denying them it."
Facebook said it removed more than 1.5 million versions of the attacker's live video feed of his mosque attack in Christchurch. Other platforms such as YouTube and Twitter similarly struggled to contain the spread of the gruesome footage. At the same time, users worldwide read through the attacker's manifesto, in which he laid out his worldview in a Q&A format.
