Luigi Mangione admitted in federal court that he stalked and shot UnitedHealthcare CEO Brian Thompson, a grim confirmation for Thompson's family and a legal gamble that may keep Mangione from dying in prison.

• He described tracking Thompson to an investor conference in New York by emailing the company while pretending to be a big investor, then using a 3D-printed gun with a silencer.
• Pleading guilty to the two federal stalking charges takes the death penalty off the table and avoids a public trial.
• His lawyers immediately moved to throw out the separate New York murder case under the state's double jeopardy law, which is stronger than the federal version.
• If that works and the federal sentence lands around 40 years, he could walk free in his 60s, since federal inmates typically serve 85% of a term.
• Even after the confession, a slice of the public still treats him as a hero and calls the killing an act of protest against corporate power.

Outlook: A New York ruling on double jeopardy is due before the September 8 state trial date, with federal sentencing set for December 18.