WASHINGTON (AP) — Theodore “Ted” Kaczynski, the Harvard-educated mathematician who retreated to a dingy shack in the Montana wilderness and ran a 17-year bombing campaign that killed three people and injured 23 others, died Saturday. He was 81.

Branded the “Unabomber” by the FBI, Kaczynski died at the federal prison medical center in Butner, North Carolina, Kristie Breshears, a spokesperson for the federal Bureau of Prisons, told The Associated Press. He was found unresponsive in his cell early Saturday morning and was pronounced dead around 8 a.m., she said. A cause of death was not immediately known.

Ted Kaczynski’s most notable work, his manifesto titled Industrial Society and Its Future, can be read in full here: https://unabombermanifesto.com/