Theodore “Ted” Kaczynski, the Harvard-educated mathematician who ran a 17-year bombing campaign that killed three people and injured 23 others, died Saturday. He was 81.

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.

Kaczynski has been portrayed in and inspired multiple works. These include the 1996 television film Unabomber: The True Story, the 20011 pla P.O. Box Unabomber, and the 2021 film Ted K. He also authored several books.

He had been held in the notorious federal Supermax prison in Florence, Colorado, since May 1998 before being transferred to the prison medical facility.

Kaczynski was sentenced to four life sentences plus 30 years for committing 16 bombings from 1978 and 1995, permanently maiming several of his victims. He later issued a “manifesto” detailing his reasons for committing the crimes, blaming technology for society’s ills. The manifesto, “Industrial Society and Its Future,” was published by the Washington Post and New York Times under threat of more attacks. Ironically, the publication drew the attention of Kaczynski’s brother, who recognized the language and sentence patterns and called in to authorities.

The Unabomber’s homemade bombs led to change in mailing and boarding procedures for airlines, and at one point shut down air travel on the West Coast in July 1995.

Authorities captured him in April 1996. He was arrested at a 10-by-14-foot plywood and tarpaper cabin outside Lincoln, Montana. Inside were journals, a coded diary, explosive ingredients and two completed bombs.

The Associated Press contributed to this story.