CHRISTCHURCH, New Zealand — The suspected gunman in the New Zealand mosque massacres, Australian Brenton Harrison Tarrant, 28, pleaded not guilty to all charges when he appeared in the Christchurch High Court on Friday.

Previously charged with 50 counts of murder and 39 of attempted murder, Tarrant faced an amended charge of murder Friday following the death of Turkish national Zekeriya Tuyan, 46, on May 2, two additional charges of attempted murder and a charge of engaging in a terrorist act under the Terrorism Suppression Act of 2002, developed in the global fallout after the Sept. 11, 2001, attacks.

He is the first person to be charged under the country’s anti-terrorism legislation.

Tarrant appeared by video link from Auckland’s Paremoremo Prison, New Zealand’s only maximum-security prison, where he is being held in isolation.

Locals in Christchurch, New Zealand laid flowers and notes of support on March 16, in memory of the victims killed in the fatal shooting that left 50 dead. (Adriana Usero/The Washington Post)

Tarrant, in a gray sweatshirt with short cropped hair, was in a small cell flanked by three prison officers in body armor vests — who left as the proceeding began. He appeared to smirk as counsel entered not-guilty pleas on his behalf.

Justice Cameron Mander said mental-health assessments by the prosecutors and defense showed Tarrant to be fit to stand trial. His trial will begin May 4, 2020. Defense attorney Shane Tait indicated they may seek a change of venue for the trial, which is expected to take more than six weeks.

Eighty survivors of the massacre, some injured, and their families attended the hearing.

Omar Nabi, who lost his father in the attacks, expressed growing frustration with the drawn-out legal process and the emotional toll it is taking on his community. “I am really disgusted at this court hearing,” he said.

Mander ordered that no filming or recording take place in the court and that existing images of Tarrant be pixelated. The names of the attempted murder victims are no longer suppressed, except due to age, he said.

Steve Addison contributed to this report.