Ted Kaczynski, better known as the Unabomber, has been found dead in his jail cell by prison officers, US media says, citing prison officials, APA reports citing BBC.
Kaczynski, 81, was discovered early on Saturday at a federal prison medical facility in North Carolina.
He was sentenced to life without parole in 1996 after evading capture for almost two decades.
He pleaded guilty to killing three people and injuring 23 more during his spree between 1978 and 1995.
Prison guards at the North Carolina facility discovered Kaczynski's body this at around 08:00 local time, US media reported.
Before suffering from declining health which prompted his transfer to the facility in December 2021, he had been held at the federal Supermax prison in Florence, Colorado, since May 1998.
Kaczynski was a man who fascinated America for decades and his violent campaign, which left a number of his victims permanently maimed. He later became the focus of numerous TV documentaries.