Mark Anderson, 36, of Mankato, Minnesota, was arrested and charged with impersonating an FBI agent in a foiled bid to free Mangione from the Metropolitan Detention Center, the notorious Brooklyn lockup where he is held while awaiting state and federal murder trials in the killing of UnitedHealthcare CEO Brian Thompson.

A criminal complaint filed against Anderson did not identify the person he attempted to free. A law enforcement official familiar with the matter confirmed it was Mangione. The official was not authorized to speak publicly and did so on condition of anonymity.

Anderson is expected to make an initial appearance Thursday in Brooklyn federal court. Online court records did not contain information on a lawyer who could speak on his behalf. A message seeking comment was left with a spokesperson for Mangione’s legal team.

According to the criminal complaint, Anderson approached the jail intake area around 6:50 p.m. Wednesday and told uniformed jail officers that he was an FBI agent in possession of paperwork “signed by a judge” authorizing the release of a specific person in custody at the jail.

When the officers asked for his federal credentials, Anderson showed them a Minnesota driver’s license, threw numerous documents at them and claimed to have weapons, the criminal complaint said. Officers searched Anderson’s bag and found a barbecue fork and a circular steel blade, the complaint said. In a photo included in the complaint, the blade appeared to be a small pizza cutter wheel.

Anderson had traveled to New York from Mankato, about 67 miles (107 kilometers) southwest of Minneapolis, and was working at a pizzeria after another job opportunity fell through, the law enforcement official said.

The attempt to free Mangione happened during a critical stretch in his legal cases.

Hours before Anderson’s arrest, the Manhattan district attorney’s office sent a letter urging the judge in Mangione’s state case, Gregory Carro, to set a July 1 trial date.

On Friday, Mangione will be in court for a conference in his federal case. The judge in that case, Margaret Garnett, is expected to rule soon whether prosecutors can seek the death penalty and whether they can use certain evidence against him.

Last week, Garnett scheduled jury selection in the federal case for Sept. 8, with the rest of the trial happening in October or January, depending on whether she allows prosecutors to seek the death penalty.

Mangione has pleaded not guilty in both cases. The state charges carry the possibility of life in prison.

A cause célèbre for people upset with the health insurance industry, Mangione has attracted legions of supporters, some of whom have regularly turned up at his court appearances. Some have donned green clothing, the color worn by the Mario Bros. video game character Luigi, as a symbol of solidarity, and some have brought signs and shirts with slogans such as “Free Luigi” and “No Death For Luigi Mangione.”

Thompson, 50, was killed on Dec. 4, 2024, as he walked to a midtown Manhattan hotel for UnitedHealth Group’s annual investor conference. Surveillance video showed a masked gunman shooting him from behind. Police say “delay,” “deny” and “depose” were written on the ammunition, mimicking a phrase used to describe how insurers avoid paying claims.

Mangione, a 27-year-old Ivy League graduate from a wealthy Maryland family, was arrested five days later at a McDonald’s in Altoona, Pennsylvania, about 230 miles (about 370 kilometers) west of Manhattan.

After several days of court proceedings in Pennsylvania, Mangione was whisked to New York and sent to the Metropolitan Detention Center.

The jail is also home to former Venezuelan President Nicolás Maduro and his wife, Cilia Flores, who are facing drug trafficking charges. Its former inmates include hip-hop mogul Sean “Diddy” Combs and cryptocurrency fraudster Sam Bankman-Fried.