The four-day sentencing hearing of the terrorist responsible for the Christchurch mosque attacks, the worst mass shooting in New Zealand’s modern history, began Monday morning, according to a local daily.

Brenton Tarrant, 29, an Australian white supremacist who initially planned to attack three mosques, admitted killing 51 Muslims as they were preparing for Friday prayers on March 15, 2019.

He has pleaded guilty to 51 charges of murder, 40 counts of attempted murder and a charge of engaging in a terrorist act, The New Zealand Herald reported.

The incident sent shockwaves around the world, with Prime Minister Jacinda Ardern introducing laws to make it harder for New Zealanders to access firearms.

The sentencing of Tarrant — who arrived in New Zealand in 2017 and lived in Dunedin city — began at Christchurch High Court, attended by survivors and victims’ families.

Christchurch Supreme Court Judge Cameron Mander has been appointed for the hearing.

At the hearing, Crown prosecutor Barnaby Hawes read the 26-page summary of facts while the judge cautioned that its content would be “distressing” but necessary to be stated in open court.

The far-right extremist, who appeared, is expected to face over 60 victims who will read “impact statements” during the four-day process.

He sacked his legal team last month and is representing himself in court.

While live reporting from the courtroom is banned, personal protective equipment was made available to in-person attendees.

In his interview, Tarrant admitted that he was planning to attack other mosques in New Zealand before deciding on Christchurch.

More than 300 people in 15 countries will have access to a livestream of the hearing with simultaneous translation in eight languages.

Tarrant began his terrorist attack at Al Noor Mosque, where he killed 44 and wounded 35, then drove to Linwood Islamic Center, where he killed another seven worshippers and injured five.

He planned to burn down the mosques after the shootings and head to a mosque in Ashburton but was arrested by police several streets away.

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