Anthony James Kazmierczak, 55, pleaded guilty in U.S. District Court to one count of assaulting a United States officer in connection with the Jan. 27 incident, in which prosecutors said he sprayed Omar with apple cider vinegar from a syringe during a public event focused on immigration enforcement policies.

The Justice Department said Kazmierczak acknowledged during a hearing before U.S. District Judge Joan Ericksen that he had planned the assault in advance and acted because he disagreed with Omar’s positions on immigration and federal enforcement actions.

The attack occurred as Omar criticized the U.S. Immigration and Customs Enforcement agency’s operations in Minnesota and discussed fatal shootings involving federal agents in Minneapolis. Authorities said the liquid sprayed on Omar’s clothing and skin was later confirmed through laboratory analysis to contain acetic acid.

Omar was not injured.Security personnel subdued Kazmierczak after he shouted and gestured toward Omar during the event, according to officials. He was later arrested, while the town hall resumed after a temporary disruption.Omar, a Somali-born Muslim lawmaker who arrived in the United States as a refugee child and became a U.S. citizen in 2000, has frequently been the target of political attacks and threats linked to her outspoken criticism of Republican immigration policies and U.S. foreign policy.

President Donald Trump has repeatedly criticized Omar publicly and on social media, including remarks questioning her place in the United States and calling for punitive action against her. Civil rights advocates and political analysts have warned that increasingly hostile rhetoric directed at elected officials has contributed to a broader rise in political intimidation and violence across the country.

The Justice Department did not immediately disclose a sentencing date. Federal assault charges involving attacks on elected officials can carry prison terms and financial penalties depending on the severity of the offense and intent established by prosecutors.

The three-judge panel dismissed Tarrant’s claim that harsh prison conditions and poor mental health had caused him to plead guilty involuntarily in March 2020, concluding there was no evidence he had suffered from a mental impairment that affected his legal judgment.

“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 their decision.

The court said the Australian national, now 35, had attempted to mislead judges about his mental state in what it described as “a weak attempt to advance an appeal,” adding that evidence showed he had made an informed and rational decision when he admitted guilt.

Tarrant carried out the attacks in March 2019, driving to two mosques in Christchurch during Friday prayers and opening fire with semiautomatic weapons, killing 51 people and injuring dozens more in New Zealand’s deadliest modern mass shooting.

His guilty pleas a year later spared victims’ families and survivors from a lengthy public trial, which many feared would give him a platform to spread extremist views.The appeal court noted that Tarrant’s bid to challenge those pleas was filed 505 days after the legal deadline, but it proceeded to hear the matter because of its public significance.

During a five-day hearing in February, Tarrant argued that “irrationality” caused by poor mental health had temporarily led him to abandon his white supremacist ideology and plead guilty.

The judges rejected that argument, saying prison staff, mental health professionals and his former lawyers did not support his claims. They also noted that he had accepted the summary of facts presented by police and the sentencing judge, while the evidence against him was overwhelming.

That evidence included video footage of the attack that Tarrant filmed himself and livestreamed online, clearly showing his face, as well as a manifesto outlining his racist ideology that he published under his real name before the shootings.

The ruling also disclosed that Tarrant sought to abandon the appeal shortly after presenting his case in February, but judges refused, saying the matter was of “significant public interest and should be finally determined.”They said he appeared to conclude the hearing was not going in his favor and then attempted to withdraw the case after proceedings ended.

Tarrant was sentenced in August 2020 to life imprisonment without parole, the first such sentence in New Zealand’s history. He remains in Auckland Prison.The judges allowed him to abandon a separate appeal against that sentence, which had been scheduled to be heard later in 2026.