A white supremacist who killed 51 people at two New Zealand mosques has appeared in court to try and withdraw his guilty plea. Australian Brenton Tarrant is serving a life sentence with no parole after admitting to murdering the 51 people and attempting to murder another 40 in the March 2019 attack on worshippers during Friday prayers in Christchurch. He initially denied the charges, but changed his plea a year after the attack. The 35-year-old, who also admitted one count of terrorism, has now launched an appeal, filed out of time, arguing he was incapable of making rational decisions at the time because of 'torturous and inhumane' conditions in prison. He also wants to appeal against his sentence. The hearing at New Zealand's Court of Appeal in Wellington is scheduled to run all week, with Tarrant expected to give evidence via video link. The massacre at Al Noor mosque and Linwood Islamic Centre - parts of which were live-streamed - led to stricter gun laws in New Zealand. Victims and family members will be able to watch the hearing via a delayed broadcast. Among those planning to attend is Aya al-Umari, who lost her older brother Hussein in the attack on Al Noor mosque. 'I very distinctly remember that I left court after the sentencing thinking "Right, the trauma chapter is now closed, time to heal, time to focus on your own mental well-being," but then it pops up again and again,' al-Umari told the BBC. She said she was preparing for a tough week, seeing the man who murdered her brother on screen, but emphasized he means absolutely nothing to her at this stage. Tarrant was born in New South Wales, Australia, but moved to New Zealand in 2017 - the prosecutorial date when he started planning his attacks against the Muslim community. He was active on fringe online forums and before the attack, he had posted a 74-page manifesto online. Within a month of the shootings, the country's parliament had voted overwhelmingly to ban military-style semi-automatic weapons. At the time of the sentencing in August 2020, then Prime Minister of New Zealand Jacinda Ardern stated that life imprisonment without parole meant Tarrant would have 'no notoriety, no platform... and we have no cause to think about him, to see him or to hear from him again.' If the three appeal court judges decide he can withdraw his guilty plea, the case could potentially go to trial on all charges.