WELLINGTON, New Zealand — The white supremacist who shot and killed 51 Muslims at two mosques in Christchurch, New Zealand, lost an attempt to abandon his guilty pleas in a Court of Appeal ruling Thursday.

The panel of three judges dismissed Brenton Tarrant’s claim that harsh prison conditions prompted his involuntarily admission to the terrorism, murder and attempted murder charges he faced. The Australian man, who is now 35, murdered 51 worshippers and injured dozens more in March 2019 when he drove to two Christchurch mosques and opened fire with semiautomatic weapons during Friday prayers.

Tarrant’s guilty pleas in March 2020 brought relief to bereaved families and survivors of the attack, who dreaded the prospect of a lengthy trial and feared he would use it to air his hateful views. The failure of his appeal bid — which the court noted was made 505 days after the legal deadline for it to be filed — means such a trial has again been averted.

At the court’s five-day hearing in February, the attacker argued his admissions of guilt were provoked by “irrationality” induced by poor mental health, which led him to desert his racist views for a time. The judges concluded, however, that his claims of mental illness were inconsistent and weren’t supported by prison staff, mental health professionals or lawyers who had earlier represented him.

“He was not suffering from a mental impairment or any other form of mental incapacity which rendered him unable to voluntarily change his pleas to guilty,” the judges wrote in Thursday’s ruling. “He endeavoured to mislead us about his state of mind in a weak attempt to advance an appeal in circumstances where all other evidence demonstrated that he made an informed and totally rational decision to plead guilty.”

The court’s ruling also revealed that Tarrant sought to abandon his appeal shortly after making his case at the hearing in February. The judges rejected that bid too, writing that the case was “of significant public interest and should be finally determined.”

They suggested that Tarrant “began to form the opinion that the hearing was not proceeding in his favour, and as a result decided to file a notice of abandonment after the hearing concluded.” New Zealand law doesn’t require judges to allow an appellant to quit an appeal bid once it’s underway.

Tarrant, who has since fired the lawyers acting for him in February, remains in Auckland Prison, where he was sentenced in August 2020 to spend life in prison without the chance of parole. The judges allowed him to abandon his appeal that sentence, which was scheduled to be heard later in 2026.

The Australian-born man moved to New Zealand in 2017 with a plan to commit a mass shooting. He amassed a cache of weapons and made a reconnaissance trip to the sites of his planned crimes before the attack.

The appeal court judges wrote that Tarrant had accepted the summary of facts presented to him by the police and the sentencing judge and noted that the case against him was “overwhelming.” Evidence included footage of the attack that the shooter filmed himself and livestreamed on the internet, in which he showed his own face, and a document outlining his racist views that he published online before the attacks under his real name.