Luigi Mangione Will Face Federal Charges in Connection with Brian Thompson's Death: Source

Luigi Mangione is now expected to face federal charges in connection with the killing UnitedHealthcare CEO Brian Thompson in addition to state charges in New York and Pennsylvania, a Justice Department source confirms.

Federal prosecutors at the Southern District of New York are expected to unveil new charges against Mangione on Thursday, Dec. 19, the source says. The source didn’t specify what charges he will face.

The news comes after Mangione waived his right to an extradition hearing in Pennsylvania on Thursday morning and was transferred to the custody of the New York City Police Department, who will take him back to Manhattan to face first-degree murder charges filed by the Manhattan District Attorney.

Mangione will also have to return to court in Pennsylvania to face state weapons and forgery charges on Feb. 24, the judge ruled on Thursday.

Mangione’s lawyer, Karen Friedman Agnifilo, did not immediately return PEOPLE’s requests for comment.

In a statement to ABC News, Agnifilo said: “The federal government’s reported decision to pile on top of an already overcharged first-degree murder and state terror case is highly unusual and raises serious constitutional and statutory double jeopardy concerns.”

Mangione was met outside the courthouse by throngs of supporters bearing “Free Luigi” signs, as well as signs deriding the healthcare industry.

On Tuesday, Dec. 17, a New York grand jury voted to indict Mangione on first- and second-degree murder charges alleging he committed an act of terrorism. He also faces charges for possessing weapons and forged instruments.

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The Ivy League-educated scion of a prominent Maryland family is the prime suspect in the killing of Thompson, who was gunned down on Dec. 4 in Midtown Manhattan by a masked assailant who then fled the scene on a bicycle, evading authorities.

Five days later, Mangione was arrested at an Altoona, Pa., McDonald’s after a customer recognized the suspected killer from images put out by New York police. He had been held in Pennsylvania prison since then.

Police believe Mangione harbored an animus towards corporate America, particularly the healthcare industry.

The words “deny” and “depose” were found on shell casings at the scene, while “delay” was found on a bullet, per Bragg’s office — similar to a phrase used to describe the health insurance industry’s practices for scuttling claims. Police also say they found a manifesto in his possession, in which he criticized the health insurance industry and described them as “parasites” who “had it coming.”