Luigi Mangione has admitted in open court that he stalked and fatally shot UnitedHealthcare CEO Brian Thompson outside a Manhattan hotel. Mangione described manufacturing a firearm with a 3D printer, attaching a silencer, posing as an investor and researching Thompson’s conference before the attack. He linked his actions to years of pain and anger toward the health-insurance system and acknowledged that the killing was illegal. The confession establishes responsibility in the federal case but does not automatically resolve New York’s separate murder prosecution. Watch.