Tarrant was arrested along with two other men and a woman. He is understood to have been charged with murder and was due in court today.
Tarrant maximised his impact on social media by flagging up the attack on 8chan half an hour earlier, using internet jokes and the names of online celebrities in his manifesto to promote it.
In naming PewDiePie, a British-based YouTuber with 89.5 million subscribers, and Candace Jones, a US conservative commentator with 1.13 million Twitter followers, he generated publicity from their attempts to dissociate themselves from him.
His “manifesto” claiming “Fortnite trained me to be a killer” was similarly designed to stir reaction from the game’s followers.
It emerged on Friday that three days before the shooting, Tarrant photographed his guns, daubed with far-Right slogans, and posted them on his Twitter account, knowing the images would be dredged up after the attack.