A man has been arrested after allegedly posing as a federal agent to break accused killer Luigi Mangione out of his Brooklyn jail holding centre.

Mark Anderson, who allegedly posed as an FBI agent, walked into the intake section of the MDC Brooklyn jail on Wednesday, January 28. It is reported that the 36-year-old tried to help accused UnitedHealthCare CEO killer, Luigi Mangione, out of prison.

The Mirror US reported that Anderson handed over his driver's license when Bureau of Prisons personnel at the Metropolitan Detention Center in Brooklyn for his credentials.

Anderson also showed officials random documents when asked for a court order, including a form detailing how to sue the Department of Justice.

The complaint did not identify the inmate by name, but a person in law enforcement confirmed that it was 27-year-old Mangione, according to multiple sources.

Anderson said he had weapons in his bag when jail staff moved to apprehend him. Staff found a barbecue fork and what appeared to be a pizza cutter inside his backpack.

He was arrested hours after state prosecutors in Manhattan Supreme Court urged a judge to set Mangione's murder trial for July.

Mangione was arrested days after United Healthcare of Brian Thompson was shot dead on December 4, 2024 while walking into a Manhattan hotel for an investors' event by UnitedHealth Group.

Mangione is changed with stalking and fatally shooting Thompson and has pleaded not guilty in both cases. Federal prosecutors are trying to impose the death penalty on Mangione if he is convicted.

Police said they found a gun and a manifesto in Mangione's backpack.

Mangione's attorneys have argued that the chain of custody for the evidence found in his backpack was not appropriately followed. The defense also claims that he was not read his Miranda Rights.