New York, New York - Luigi Mangione, accused of gunning down an insurance executive in cold blood in a slaying that has divided Americans, pleaded not guilty to murder charges Friday, after he was arraigned in court.

Mangione pleaded not guilty in a Manhattan court to the four-count indictment that is the first case in which the Justice Department is seeking the death penalty since Donald Trump returned to the White House.

Mangione has been charged in both New York state and federal court for slaying UnitedHealthcare CEO Brian Thompson in a case that has stirred debate about political violence and the state of the healthcare system in the US.

In the state case, Mangione has also pleaded not guilty and could face life imprisonment with no parole, if convicted.

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Early on December 4, Mangione allegedly tracked Thompson in New York, walked up behind him, and fired several gunshots from a pistol with a silencer, federal prosecutors said. He had traveled to the city by bus from Atlanta about 10 days before the crime.

Mangione was arrested in Altoona, Pennsylvania, on December 9, following a tip from staff at a McDonald's restaurant after a days-long manhunt.