Luigi Mangione pleaded not guilty to a federal murder charge in the killing of UnitedHealthcare CEO Brian Thompson.

The prosecutors have officially stated their intention to pursue the death penalty in this case, while the judge cautioned Justice Department officials against making any public remarks that could compromise the defendant’s right to a fair trial.

Mangione, 26, stood between his lawyers and leaned toward a tabletop microphone as he entered the plea in Manhattan federal court.

This marks the first instance of the Justice Department seeking capital punishment since President Donald Trump’s return to the White House on January 20, when he pledged to resume federal executions, which had been paused by the previous administration.

According to Mangione’s attorneys, Bondi’s public statement—accompanied by posts on her Instagram account and a television appearance—was merely a “political stunt” that breached long-standing Justice Department guidelines, tainted the grand jury proceedings, and violated Mangione’s constitutional right to due process.

After Mangione lawyer Karen Friedman Agnifilo raised the issue again on Friday, Garnett instructed federal prosecutors to convey to Bondi and other Justice Department officials that court rules prohibit any pretrial publicity that could interfere with a defendant’s right to a fair trial.

Mangione’s federal indictment includes a charge of murder through use of a firearm, which carries the possibility of the death penalty. The indictment also charges him with stalking and a gun offence.

Surveillance video showed a masked gunman shooting Thompson from behind as the executive arrived for UnitedHealthcare’s annual investor conference. Police say the words “delay,” “deny” and “depose” were scrawled on the ammunition, mimicking a phrase commonly used to describe how insurers avoid paying claims.

The killing and ensuing five-day search leading to Mangione’s arrest rattled the business community while galvanising health insurance critics who rallied around Mangione as a stand-in for frustrations over coverage denials and hefty bills.

Mangione was arrested December 9 in Altoona, Pennsylvania, about 370 kilometres west of New York City and whisked to Manhattan by plane and helicopter.

Police said Mangione had a 9mm handgun that matched the one used in the shooting and other items including a notebook in which they say he expressed hostility toward the health insurance industry and wealthy executives.

Among the entries, prosecutors said, was one from last August that said “the target is insurance” because “it checks every box” and one from October that describes an intent to “wack” an insurance CEO. UnitedHealthcare, the largest US health insurer, has said Mangione was never a client.