UnitedHealthcare CEO Brian Thompson was shot and killed on a Manhattan street in December 2024, sparking a nationwide reckoning over healthcare system failures. NBC's Lester Holt investigates the murder, the accused shooter Luigi Mangione's transformation from wealthy tech worker to accused assassin, and why millions view the killing as justified resistance rather than murder. Investigators discovered the murder was targeted through three inscribed bullet casings reading 'Delay, Depose, Deny'—words criticizing how the health insurance industry denies claims—immediately shifting focus from random crime to deliberate execution.