The man who sprayed vinegar at the Democratic US House member Ilhan Omar during a Minneapolis town hall was sentenced Thursday to 14 months in prison after reaching a deal with prosecutors.

The sentencing of 56-year-old Anthony Kazmierczak came nearly eight months after the 27 January assault. At the time, Minneapolis was facing an immigration crackdown that led to angry protests, arrests and the killing of two US citizens by federal officers.

Kazmierczak was also sentenced to three years of supervised release, which includes no contact with Omar. US marshals escorted him from the courtroom after he was sentenced.

“This wasn’t a spur-of-the-moment act,” the US district judge Joan N Ericksen said before handing down the sentence, noting that Kazmierczak had secured tickets for the town hall weeks in advance.

“An attack on a public figure is not a political statement. It is misguided, selfish and inconsistent with any concept of a free or democratic society,” Ericksen added. She also said spraying anything at an elected official “is a terrifying thing. And you knew that when you did it.”

Kazmierczak, who has been diagnosed with Parkinson’s disease, shook visibly at times as he sat at the defense table. He spoke quietly and haltingly, occasionally wiping away tears as he stood before Ericksen.

He spoke about being a good neighbor – and how his troubles with insurance companies as well as prison had exacerbated his ailments. His attorney, John Fossum, argued that Kazmierczak had not been taking his mental health medications before the attack, lowering his inhibitions and contributing to what happened.

“I’ve spent enough time in jail thinking,” Kazmierczak said, his voice barely audible. “I really apologize to her for having put her through that,” he said, referring to Omar.

In an earlier hearing, Kazmierczak was unable to explain his actions, saying only “it’s fuzzy” when Ericksen asked what he remembered.

“I’m sorry if I scared you,” he wrote to Omar after the attack.

During the town hall, witnesses saw Kazmierczak jump up from the audience, spraying liquid from a syringe at Omar and saying she was “splitting Minnesota apart”. Omar’s security officers tackled Kazmierczak and turned him over to police, who arrested him.

Omar was not injured and continued with the town hall after the arrest.

Authorities later determined he had sprayed her with a mixture of water and apple cider vinegar. He pleaded guilty to assaulting a US officer.

The government sentencing memorandum, submitted to the court by prosecutors, said he had texted at least three people indicating he planned to do something at the meeting involving Omar “but would not answer their questions about his intent”.

He also sent messages to a neighbor to arrange for dog care and asking for bail bond company contact information.

The sentencing memo said Kazmierczak had long struggled with alcohol abuse and had “a history of mental and emotional health concerns” and a string of health issues tied to his 2022 Parkinson’s disease diagnosis.

Omar, a refugee from Somalia, has long been a target of Donald Trump’s anti-immigrant rhetoric across his two presidencies. In 2019, after Omar’s election to Congress, Trump said she should “go back” to her country of birth. He has described her as “garbage” and said she should be investigated.

In social media posts, Kazmierczak had criticized Joe Biden – who was president between Trump’s two Oval Office terms – and referred to Democrats as “angry and liars”. He wrote that Trump wants the US to be “stronger and more prosperous”.

His attack came as the Minneapolis area was on edge due to the crackdown, with protesters often facing off against convoys of immigration officers and conservatives criticizing protesters.