A judge is hearing testimony this week from those affected by the rampage on March 15, 2019, when Tarrant gunned down worshipers at the Al Noor Mosque and Linwood Islamic Center in Christchurch. It was the worst act of violence in New Zealand's modern history.
The 29-year-old Australian, who live-streamed the massacre on Facebook, pleaded guilty earlier this year to 51 counts of murder, 40 counts of attempted murder and one count of committing a terrorist act.
In a recorded statement played to the High Court on Tuesday, Farisha Razak, whose father Ashraf Ali was killed at Al Noor Mosque, said Tarrant was a "monster" who had accomplished nothing except to unite people against him.
"Nobody wants you, buddy. You're rejected by your country, your parents and your friends. You're a loser and don't deserve to see the light of day," she said.
Mirwais Waziri, who survived the attacks, said that as an Afghan living in New Zealand during the war-on-terror era, people had sometimes called him a terrorist — "for fun or a joke."
But today, he said, facing Tarrant, "you are called a terrorist." The remark prompted spontaneous applause from visitors to the court, some of whom had traveled from overseas.
This week's sentencing hearing, where Tarrant is representing himself, is unfolding under tight security and capacity restrictions because of the coronavirus pandemic.
The scenes in the courtroom on Tuesday were sometimes tense, victims' voices cracking with emotion as they faced Tarrant and described how he began shooting during Friday prayers.
Nathan Smith, 46, recounted how "people were dying all around me" at the Al Noor Mosque, where 44 of Tarrant's victims were killed.
"I held a 3-year-old boy in my arms, praying that he was still alive — he was not. You took him away," he told Tarrant.
"You have changed my life forever, and I will never forgive you."
Then followed one of the rare occasions when Tarrant showed emotion. The gunman appeared to smile briefly after Smith suggested that Tarrant should read the Koran "when you get a free minute, which you'll have plenty of."
Tarrant's atrocities shocked New Zealand, a country with little experience of gun massacres or domestic terrorism. In response, Prime Minister Jacinda Ardern tightened gun laws, outlawing most semiautomatic firearms and initiating a government buyback of existing weapons.
Judge Cameron Mander is expected to hand down a sentence by Thursday. In most cases in New Zealand, the penalty for murder is life imprisonment, with a non-parole period of at least 17 years for particularly serious murders.
But Tarrant could become the first person in the country to face a life sentence without parole, said Graeme Edgeler, a Wellington-based lawyer and legal commentator.
"Given the seriousness of the charges, and the number of victims, life without parole is a serious possibility in Tarrant's case," he said in an email.
Earlier on Tuesday, Tarrant, who was wearing gray clothing and was flanked by four police officers, repeatedly covered his mouth with his hands or rested his chin on his knuckles as he listed to harrowing personal impact statements.
Rosemary Omar told the gunman he had effectively given her a life sentence when he attacked Muslim worshipers, including her 24-year-old son Tariq Omar, less than two miles from where the hearing was taking place.
"This monster had no right to take my son from me," she said. "I feel there is a permanent shadow cast over everything now."
Kyron Gosse, the nephew of shooting victim Linda Armstrong, told how he tried frantically to contact his aunt on the day of the attacks, with "call after call going to voice mail."
"I want to share with you what it means to me to be just an ordinary guy caught up in the horror inflicted by this man," Gosse said, recounting how his aunt was "shot in the chest and left to bleed out on the floor as her life slipped away."
"I want you to understand the utter gut-wrenching horror to learn that this event happened on New Zealand soil. I want you to understand my utter rage at learning this man was a guest to New Zealand."
Tarrant, he said, "stole our nation's innocence."