By Luc Cohen

NEW YORK (Reuters) – Luigi Mangione, the suspect in the Dec. 4 killing of UnitedHealth Group (NYSE:UNH) executive Brian Thompson, faces two separate sets of murder charges in state and federal court in New York.

What Charges Does Mangione Face in Federal Court?

Federal prosecutors in Manhattan on Thursday charged Mangione, 26, with:

• One count of murder through use of a firearm
• One count of using a firearm silencer during a violent crime
• Two counts of interstate stalking for allegedly surveilling Thompson.

These charges were based on a complaint filed by the FBI. Prosecutors may seek a grand jury indictment of Mangione, which could include different charges.

What Could the Consequences of Those Charges Be?

The federal murder charge is eligible for the death penalty, should prosecutors seek it. Otherwise, Mangione could face life in prison if convicted on the murder charge, and a mandatory 30-year sentence if convicted of using a silencer.

The possibility of the death penalty may provide an incentive for Mangione to seek a plea agreement, said Anna Cominsky, a professor at New York Law School. "There is no greater bargaining chip," Cominsky noted.

How Would a Death Penalty Case Work?

Federal prosecutors would need the approval of the U.S. attorney general to pursue the death penalty. A potential trial would proceed in two phases: one to determine Mangione's guilt, and, if found guilty, a second trial for a jury to decide whether to sentence him to death.

Zachary Margulis-Ohnuma, a New York defense lawyer, pointed out that prosecutors more frequently seek the death penalty for crimes with multiple victims or when law enforcement officers are killed. Last year, a federal jury deadlocked on whether to impose the death penalty on Sayfullo Saipov, who was convicted of killing eight people during a 2017 Manhattan attack inspired by the Islamic State. Saipov was instead sentenced to eight consecutive life terms of incarceration.

"It's hard to see a jury voting for death in this case," Margulis-Ohnuma said.

What Are the State Charges and Their Potential Punishments?

On Tuesday, Manhattan District Attorney Alvin Bragg announced an 11-count grand jury indictment of Mangione on charges including first-degree murder and murder as an act of terrorism.

If convicted on all state charges, Mangione could face life in prison without the possibility of parole, as New York's highest court ruled the death penalty unconstitutional in 2004. Despite the ban, federal prosecutors are still permitted to seek executions for federal cases.

How Will the Two Cases Advance?

The state case is expected to proceed to trial before the federal case, according to the Manhattan U.S. Attorney's office. Bragg noted that there is precedent for state and federal prosecutions proceeding as parallel matters.

Mangione's lawyer, Karen Friedman Agnifilo, highlighted a potential conflict, stating that the state case includes a terrorism charge accusing Mangione of seeking to intimidate a population or influence policy, while the federal case centers on his alleged stalking and killing of an individual.

"These are two completely different theories," Friedman Agnifilo remarked in court. "These seem like different cases."