Ted Kaczynski, known as the 'Unabomber,' died by suicide in federal prison

Theodore "Ted" Kaczynski, the man known as the "Unabomber," died by suicide in custody at a federal prison medical center in North Carolina, four people familiar with the matter told The Associated Press.

The people were not authorized to publicly discuss Kaczynski’s death and spoke to the AP on condition of anonymity.

Kaczynski, 81, was found unresponsive at about 12:25 a.m. Saturday at Federal Medical Center Butner in Butner, North Carolina, the Federal Bureau of Prisons said in a news release. Staff undertook life-saving measures and requested EMS professionals, who transported Kaczynski to a local hospital, where he was pronounced dead.

The Federal Bureau of Investigation was notified of Kaczynski's death, the Federal Bureau of Prisons said. The bureau did not state a cause of death.

Kaczynski had been in custody at FMC Butner since December of 2021, according to the Bureau of Prisons. He was serving a life sentence after sending a series of homemade bombs by mail around the country over the course of 17 years. He pleaded guilty to setting 16 explosions that killed three people and injured 23 others.

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This article originally appeared on USA TODAY: Ted Kaczynski, known as Unabomber, died by suicide in federal prison