Mark Anderson, accused of posing as FBI agent in effort to free Luigi Mangione from jail, pleads not guilty

The Minnesota man who authorities say posed as an FBI agent in a ruse to spring alleged CEO killer Luigi Mangione from a Brooklyn federal jail pleaded not guilty Tuesday to impersonating a federal employee.

Mark Anderson, 36, was arrested after he showed up at the Metropolitan Detention Center in Brooklyn on Jan. 28, claiming to be a special agent, armed with a pizza cutter and a barbecue fork and demanding the release of Mangione, who has been charged with murder in UnitedHealthcare CEO Brian Thompson's killing.

Anderson, who has a history of mental health issues, arrived at the jail's intake center and told U.S. Bureau of Prisons employees that he had paperwork "signed by a judge" authorizing Mangione’s release, according to the criminal complaint unsealed last month.

He showed jail officials his Minnesota driver’s license, told them he had weapons in his bag and threw a bunch of legal papers at them.

Earlier that day, Anderson had filed a civil suit against the FBI in federal court in Brooklyn, claiming "mental and internal unlawful inducement by Iran and the Satanic Church."

Anderson worked at Louie and Ernie's Pizza in the Bronx before his arrest, but had lost his job after he had threatened the owner with a fake gun, according to court records. The pizzeria owner, Cosimo Tiso, said that the pizza cutter found on Anderson was not from his restaurant.

During a previous court appearance, he appeared annoyed and spoke to his lawyer, Michael Weil, about the "Wall Street cartel."

At this arraignment on Tuesday, Anderson, in tan jail scrubs and leg shackles, was more subdued and entered his plea through his attorney.

Assistant U.S. Attorney Brandon Davis asked the judge to remand Anderson back into jail custody after the hearing, citing his recent criminal history, a history of substance abuse and the weapons he was carrying during the alleged jail break.

Weil said that he would reserve the right to file an application for bail at a future date.

Anderson’s next court appearance will be on Feb. 20 in front of U.S. District Judge Eric N. Vitaliano.