A man from upstate New York has been charged with threatening to assault and murder U.S. Rep. Ilhan Omar, the U.S. Attorney's Office said. Patrick Carlineo, 55, allegedly called Omar's office on March 21 and told a staffer "Do you work for the Muslim Brotherhood? Why are you working for her, she's a (expletive) terrorist. I'll put a bullet in her (expletive) skull," according to the criminal complaint.

A staffer referred the call to Capitol Police, which launched an investigation.

According to CBS Rochester, New York affiliate WROC, Carlineo initially denied to FBI agents that he had threatened to shoot the Minnesota Democrat. He told investigators he had said "if our forefathers were still alive, they'd put a bullet in her head."

Get Breaking News Delivered to Your Inbox

Investigators reminded Carlineo that lying to the FBI is a crime and there was a recording of the phone calls, WROC reports. He said he couldn't remember exactly what he said, and it could be something like that.

Carlineo also told agents that he had a .22 caliber firearm and a shotgun in his home.

Carlineo has made his initial appearance before a judge and is being held pending a detention hearing on April 10, CBS Minnesota reports.

Carlineo faces up to ten years behind bars if convicted.

Omar, who is Somali-American and wears a hijab, is one of the most vocal freshman legislators on Capitol Hill. In March, a West Virginia GOP event featured an anti-Muslim poster of Omar linking her to the Sept. 11 terrorist attacks. The poster featured a picture of planes flying into the World Trade Center with the phrase "never forget, you said" and then under it, a picture of Omar with the words "I am proof you have forgotten."

Omar, who represents Minnesota's 5th Congressional district, tweeted about the poster: "No wonder why I am on the 'Hitlist' of a domestic terrorist and 'Assassinate Ilhan Omar' is written on my local gas stations."