An inquest into New Zealand's 2019 mosque killings opened Tuesday, with relatives of the 51 people who died in the massacre hoping to discover if any lives could have been saved.

White supremacist Brenton Tarrant shot and killed 51 Muslim worshippers at two Christchurch mosques on March 15, 2019, in New Zealand's deadliest modern-day mass shooting.

Deputy chief coroner Brigitte Windley opened the inquiry in Christchurch, saying it would "look at what we may learn from this atrocity and speak for those who have lost their lives in an effort to protect the living".

Maha Galal, spokesperson for the "15 March Whanau Trust" representing some of the victims' relatives, said there was an "urgent need for answers".

"Our paramount concern is to comprehend the truth," Galal said in a statement before the inquiry began.

Family and friends packed the courtroom for the emotionally charged opening session, which included a moving video tribute to each of the 51 victims. 

Detective Senior Sergeant Craig Farrant then gave an outline of the attacks, saying 49 people were murdered in the space of 19 minutes -- with two more later dying of their injuries in hospital. 

The detective described the homicide investigation launched in the wake of the attacks as "the largest" ever undertaken by New Zealand police, "with the size and scope of the offending being unprecedented in our history".

Observers were shown a harrowing video depicting Tarrant's movements around Christchurch on the day of the attack, including footage he had filmed using a GoPro camera.

Tarrant's first attack on the Al Noor mosque would ultimately result in 44 people dying.

He then drove about 10 minutes to the nearby Linwood Islamic Centre, where he would kill seven more worshippers. 

The inquest will examine the response times of police and emergency services, the medical response at each of the mosques, whether Tarrant was helped in planning the attack, and whether any lives could have been saved. 

"This pursuit of truth is crucial for healing and closure," said Galal. 

The families of the victims "are united in their pursuit of understanding, seeking clarity on whether their loved ones could have survived", Galal added.

- 'Base hatred' -

The killings carried out by Tarrant, an Australian former gym instructor from the rural New South Wales town of Grafton, horrified New Zealand and sparked global revulsion.

After admitting to 51 charges of murder, 40 of attempted murder and one of terrorism, he was sentenced in August 2020 to life imprisonment without parole.

In his sentencing, Judge Cameron Mander said Tarrant's "warped" ideology and "base hatred" led him to murder defenceless men, women and children.

Tarrant had livestreamed the killings on social media and published a manifesto online before carrying out the attacks.

Then-prime minister Jacinda Ardern quickly moved to tighten gun laws in the aftermath and put pressure on social media giants to curb online extremism.

Galal said the victims' families hoped the inquest would provide some closure and highlight ways such an attack could be prevented in future.

"We believe that there is much we can learn from what happened on March 15, 2019, so that we are all prepared, as a community, if such a tragedy happens again which we pray will not happen."

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