NEW YORK -- Luigi Mangione, whose coldblooded killing of an insurance executive on a Manhattan sidewalk rattled the nation and struck fear in corporate America, pleaded guilty Friday to federal charges for the death of UnitedHealthcare leader Brian Thompson.

"On the morning of Dec. 4, 2024, I shot Mr. Thompson in Manhattan," Mangione solemnly told the judge during a court hearing.

Mangione, wearing tan jail garb, told the judge that after enduring severe pain, and witnessing others with similar experiences, he learned of the company's investor conference. He said he printed part of a gun using a 3-D printer and planned the killing.

U.S. District Judge Margaret Garnett said the maximum sentence was life in prison. She scheduled his sentencing for December.

Thompson's family sat in the front row of the courtroom during Friday's hearing.

The plea resolves one criminal case against Mangione but could upend or delay a separate state murder case that is scheduled to go to trial in early September.

Though the state and federal charges aren't the same, his legal team is likely to contend that he can't be tried for the same offense twice. Mangione himself previewed this argument, yelling after the scheduling of his state trial, "Double jeopardy by any common sense definition!"