Kaczynski was found unresponsive in his cell at the Federal Medical Center in Butner, N.C., early Saturday morning, according to the Bureau of Prisons. He was 81 years old and suffering from late-stage cancer at the time of his death,The Associated Pressreports.

Kaczynski killed three people and injured at least 23 more during a bombing spree that lasted from 1975 until 1995. AfterThe Washington Postpublished Kaczynski’s notorious “Manifesto” that year, Kaczynski’s brother David Kaczynski and his sister-in-law Linda Patrick recognized phrases from the note and later turned him into authorities. Kaczynski was arrested on April 3, 1996, after police surrounded his small cabin in the wilds of Lincoln, Mont.

Bureau of Prisons/Getty Images

Mugshot of Ted Kaczynski, identidentified as the domestic terrorist known as the Unabomber, April 1996

He faced several charges stemming from his fatal bombings, and in exchange for a life sentence without the possibility of parole, he pleaded guilty to each of them in 1998, thus avoiding the death penalty. Kaczynski previously attempted to hang himself with a pair of underwear while awaiting that trial,Politicoreports.

Ted Kaczynski.Michael Macor/The San Francisco Chronicle via Getty Images

Theodore ‘Ted’ Kaczynski (in orange) is guided to his arraignment by federal marshals, Helena, Montana, April 4, 1996

Michael Macor/The San Francisco Chronicle via Getty Images

Kaczynski was incarcerated at the Supermax prison in Florence, Colo. – known as the “Alcatraz of the Rockies” – for more than 20 years. In December 2021, he was moved to a prison medical facility in North Carolina due to health issues, PEOPLE confirmed through the Bureau of Prisons.

Theodore “Ted” Kaczynski is revealed as the “Unabomber” suspect during a press conference in Lincoln, Montana on April 4, 1996

His deadly bombing campaign appeared to focus on seemingly random targets, before a few similarities emerged as the FBI’s investigation continued: many were scholars and businesspeople, several had a direct tie to modern technology such as computers and airplanes, and some regions were hit more than others.

The FBI’s nearly decades-long investigation was the longest and most expensive manhunt in the nation’s history, according to the AP, ending only after his family recognized his writings.

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Kaczynski abruptly left his professorship at UC Berkeley after his second year of teaching, briefly moved back home to Illinois and lived with his parents, before moving to a cabin he built in Montana that lacked both electricity and running water.

There, Kaczynski built his bombs and mailed them to his victims with the goal of dismantling modern society, its technological advances, and its impact on the environment. At the cabin, investigators discovered bomb parts, roughly 40,000 incriminating journal pages, and a live bomb that agents reported was ready to be mailed.

source: people.com