Garret Miller's mugshot after being arrested in Texas on January 20, 2021.
CNN  — 

A Texas man charged in the January 6, 2021, attack on the US Capitol pleaded guilty Monday to threatening Rep. Alexandria Ocasio-Cortez on Twitter shortly after the riot.

On January 6, in the hours after the Capitol had been cleared of rioters, Ocasio-Cortez, a New York Democrat, posted a Tweet saying, “Impeach.” Garret Miller replied: “Assassinate AOC.”

Miller also pleaded guilty to assaulting, resisting or impeding officers, and admitted to intentionally forcing his hands on an officer while they tried to remove him from the Capitol that day.

During the hearing, federal Judge Carl Nichols read a statement of factual evidence – to which Miller agreed – that stated Miller acted with “serious intent” at the time he posted the tweet and meant for it to be a “threat.”

Miller knew Ocasio-Cortez was in Washington when he posted the tweet, causing additional concern for the congresswoman’s safety, according to the statement.

Prosecutors previously said that in the days following the attack on the Capitol, Miller had also became obsessed with identifying the police officer who fatally shot a Trump supporter during the attack and allegedly said he “deserves to die” and won’t “survive long” because it’s “huntin[g] season.”

According to court filings, Miller identified and circulated pictures of a police officer that he believed to be responsible for the shooting. “He’s a prize to be taken,” Miller allegedly said of the officer.

Investigators said that when they searched Miller’s home in Texas, they found two ropes, several firearms, ammunition, body armor and a crossbow.

Miller’s sentencing is scheduled for February 22.

CNN’s Marshall Cohen, Katelyn Polantz, Hannah Rabinowitz and Jack Forrest contributed to this report.