The man due to go on trial for the 15 March Christchurch mosque attacks has this morning pleaded guilty to all the charges he was facing.

Photo: RNZ / Simon Rogers

At the High Court in Christchurch, Brenton Tarrant admitted 51 counts of murder, 40 of attempted murder and one under the Terrorism Suppression Act.

Until today he had denied all of the charges and was scheduled to stand trial in June. The guilty plea means he has become New Zealand's first convicted terrorist.

The 29-year-old showed no emotion as he appeared via audio visual link in the High Court at around 10am.

No explanation for Tarrant's change of heart was given during today's hearing. He has been remanded in custody until May.

No sentencing date has been set as the courts continue to grapple with widespread disruption from the Covid-19 outbreak.

Photo: Supplied / Pool

On 15 March last year Tarrant walked into Al Noor Mosque, heavily armed, shortly after Jumu'ah - the most significant prayer of the week - began.

In little over six minutes he had killed 42 people.

About 10 minutes later he arrived at the Linwood Islamic Centre and, unable to find the entrance, began shooting from outside.

He killed seven people before he was chased from the mosque's grounds by worshipper Abdul Aziz, who picked up and threw a bank card reader at the gunman, and used one of Tarrant's own firearms as a spear which he threw through the terrorist's car windscreen.

A 50th victim died soon after in Christchurch Hospital, while the 51st victim passed away 48 days after the attacks.

At this morning's hearing only a small number of people were allowed into the courtroom due to the restrictions in place in the Covid-19 nationwide lockdown.

Those entering the courthouse were screened by security and court staff wearing protective masks.

The imams from the two mosques, Gamal Fouda and Abdul Alabi Lateef, acted as the Muslim community's representatives and watched as Tarrant entered his pleas.

Tarrant lived in almost total obscurity in Dunedin for almost two years before Friday, 15 March, 2019.

During that time he was part of an online fraternity of white supremacist, far-right extremists.

He had few connections in the city and was essentially a loner.

His family described how his hateful ideology appeared to form as he travelled the world following his father's death from cancer in 2010.

Tarrant travelled to the Balkans, Turkey and Pakistan, among other locations linked to the Crusades and the Islamic world, before the attack.

The murderer lived in the quiet Dunedin suburb of Andersons Bay and acquired a firearms licence and a Subaru Legacy station wagon soon after relocating to the city in 2017.

The four A-class firearms, bought using that licence, and the vehicle would be used to carry out last year's horrific attacks.

He practised shooting at the Bruce Rifle Club near Milton in South Otago, about 50 kilometres from Dunedin, for about a year in the lead-up to the attacks.

Tarrant identified Dunedin's Al Huda Mosque as the initial target for his attack before turning his attention to the two mosques in Christchurch and the mosque in Ashburton, where he expressed his anger at its utilisation of a former church.

Why the appearance happened at short notice

Police Commissioner Mike Bush said arrangements for Tarrant's appearance in court had to be made at short notice after his lawyers only indicated on Tuesday afternoon that the gunman wanted to be brought before the court.

"Police appreciate this news will come as a surprise to the victims and the public, some of whom may have wished to be present in the courtroom," Bush said.

"The two Imams from the Al Noor and Lynwood Avenue mosques were present in the courtroom as representatives of the victims, as were representatives of the media.

"Suppression orders were put in place to allow Police, Victim Court Advisors and Victim Support to advise as many of the victims as possible prior to the news being made public."

Sentencing would not take place until it was possible for all victims who wanted to attend to be present.

"Due to the Covid-19 epidemic that will not be possible for some time," Bush said.

"Police, Victims Court Advisors and Victim Support will be in touch with individual victims to update them on the sentencing process, including the process for providing Victim Impact Statements and presenting those statements at the sentencing hearing if they wish to do so.

"While the sentencing hearing is still pending, today's guilty pleas are a significant milestone in respect of one of our darkest days.

"I want to acknowledge the victims, their families and the community of Christchurch - the many lives that were changed forever. They have inspired all of us to be a kind and more tolerant community."

Bush also paid homage to the officers, police staff and prosecutors involved in New Zealand's largest ever criminal prosecution.

Police would comment further after sentencing.

Prime Minister Jacinda Ardern said the guilty plea would "provide some relief to the many people whose lives were shattered by what happened on March 15".

"These guilty pleas and conviction bring accountability for what happened and also save the families who lost loved ones, those who were injured, and other witnesses, the ordeal of a trial."

At a media conference this afternoon, Ardern said it will be deeply disappointing for victims they are not able to gather together after hearing the guilty plea.

However, she says it will be a sense of relief for everyone, particularly the Muslim community who will be spared from a trial that could have acted as a platform for the shooter.

Timeline of Christchurch terror attacks:

Around August 2017: Brenton Tarrant relocates to Dunedin and soon after buys a Subaru Legacy station wagon.

October 2017: Joins a South Dunedin gym.

November 2017: Applies for and is granted a Class-A firearms licence.

November 2017-March 2018: Buys four Class-A firearms online.

Early 2018: Tarrant joins the Bruce Rifle Club.

October 2018: Puts his gym membership on hold and travels to Pakistan where he spends time in the north of the country near the border with Afghanistan.

15 March 2019

Morning: Travels from Dunedin to Christchurch in his Subaru Legacy with his firearms and hundreds of rounds of ammunition.

1.28pm: Links to a Facebook livestream and Tarrant's manifesto are posted to an online forum.

1.31pm: Prime Minister's Office receives an email describing an attack that has taken place. Attached is the manifesto. The same email is sent to 29 others including politicians and media organisations.

1.33pm - Tarrant begins his Facebook livestream as he drives to Al Noor Mosque.

1.40pm - He arrives at the mosque where hundreds are congregated for Friday prayer. After parking in a small lane next to the building, he approaches the backdoor and begins firing.

1:46pm Tarrant leaves Al Noor Mosque, firing at people fleeing on the street. He gets back into his station wagon and begins driving east.

1.56pm - He arrives at the Linwood Islamic Centre and fires shots from outside the mosque. Chased away by worshipper Abdul Aziz and flees the mosque.

2.02pm - Two rural community police officers from Lincoln spot the gunman's vehicle on Brougham Street and ram his car off the road. He is arrested without resistance.

16 March 2019: Tarrant appears in Christchurch District Court on one holding charge of murder for a mostly administrative appearance.

4 April 2019: Police lay 50 charges of murder and 39 of attempted murder.

5 April 2019: Tarrant makes his first appearance in the High Court via audio-visual link. No plea is entered.

21 May 2019: Police amend one charge of attempted murder to murder, and lay two additional charges of attempted murder. Tarrant is also charged under the Terrorism Suppression Act, of engaging in a terrorist act.

14 June 2019: Tarrant pleads not guilty to all 92 charges. Trial is tentatively set for May 2020.

15 August 2019: The court hears the trial may be delayed by a month.

12 September 2019: Tarrant's trial is set for early June 2020, so as not to conflict with the Islam's Holy month of Ramadan.

3 October 2019: The gunman abandoned a bid to move the trial out of Christchurch.

10 December 2019: More pre-trial matters are discussed in the High Court, but Tarrant does not appear.

24 February 2020: The case is again called in the High Court but the nature of the discussions are suppressed.

26 March 2020: Tarrant appears in the High Court at Christchurch via audio-visual link and enters guilty pleas to 51 counts of murder, 40 of attempted murder and one of engaging in a terrorist act.