On Monday, Brenton Tarrant, the Australian citizen who carried out the attack, appeared in court for the start of sentencing proceedings that are expected to last at least four days. That swift action won praise from experts and the Muslim community, as the country reeled from the massacre. Hagen Hopkins/Getty Images AsiaPac/Getty Images Prime Minister Jacinda Ardern hugs a mosque-goer at the Kilbirnie Mosque on Main Wellington, New Zealand.