A Gilbert resident pleaded guilty Friday to threatening a former assistant US attorney.

James Giannakos admitted he warned she could be harmed if anything happened to a right wing Proud Boys leader.

Giannakos is being held in the Lexington County Detention Center.

He admitted he left a threatening message and apologized in federal court, The State newspaper reported.

Giannakos faces up to 5 years in federal prison and a $250,000 fine.

US Judge Terry Wooten has not yet imposed sentence.

Giannakos must cooperate with federal prosecutors on other criminal cases he may know about including the attack on the US Capitol Jan. 6.

The former prosecutor had identified Enrique Tarrio, the alleged Proud Boys leader, as a former Florida authorities’ informant.

“Miss (name of former prosecutor withheld), my name’s James. I just wanted you to know that if anything happens to Mr. Enrique Tarrio, the same thing will happen to you and your family,” Giannakos said in a message, according to a criminal charging document filed in federal court.

“I cannot believe you released the CI (confidential informant) information, if that’s even true. If anything happens to him, I promise you and your associates will pay for it. You will be held responsible.”

Giannakos was upset that Tarrio was identified as a confidential informant which could put the Proud Boys leader in danger, Giannakos’ attorney Allen Burnside told the court.

The Proud Boys are “an extremist right-wing group,” court records say.

Assistant US Attorney Jim May said the phone Giannakos used was traced to his home in Gilbert.

A search of his home found:

• Guns, pepper spray, a Washington subway map, a 24-inch police baton and military combat gear including a tactical vest, knee pads and eye protection.

• A Capitol police shield, police body camera and an officer’s helmet.

This led investigators to suspect he was involved in the Jan. 6 Capitol attack.

Giannakos’ public defender said his client had encountered the Proud Boys through online chat rooms and had seen Tarrio speak although he does not know the Proud Boys leader personally.