Monday marked the second court appearance in New York for Luigi M. since his arrest at a McDonald's restaurant in Pennsylvania, five days after UnitedHealth Group CEO Brian Thompson was killed outside a hotel in Manhattan.
Luigi Mangione, 26, was shackled and seated in a Manhattan court when he leaned over to a microphone to enter his plea.
His initial appearance in New York state's trial court was preempted by federal prosecutors bringing their own charges over the shooting.
Mangione, 26, was escorted into a 13th-floor courtoom in the New York state criminal courthouse in lower Manhattan with a court officer on each arm, and a procession of a half dozen officers following him.