The Unabomber, Ted Kaczynski, a convicted terrorist, was discovered dead in his cell early on Saturday, according to a Federal Bureau of Prisons official. He was 81.

Due to ill health, Kaczynski was transferred from a maximum security institution in Colorado to a medical facility in North Carolina in December 2021.

Before he was known as the Unabomber, in 1995, he requested that newspapers publish a lengthy book he had written, claiming that if they didn’t, the killings would continue. Later that year, on the advice of the FBI director and the U.S. attorney general, the 35,000-word manifesto was published by the New York Times and the Washington Post.

Kaczynski might not have been apprehended if it weren’t for his brother and sister-in-law’s concerns. One of the first people to recognize Kaczynski as the Unabomber after reading the Unabomber’s writing was his sister-in-law Linda Patrik.

Patrik discussed her initial suspicions that Kaczynski was behind the explosions in an interview with “20/20 on ID Presents: Homicide” in 2016.

“I’d thought about the families that were bombed. There was one in which the package arrived to the man’s home and his little 2-year-old daughter was there. She was almost in the room when he opened the package. Luckily she left, and his wife left. And then he died,” Patrik said. “And there were others. And so I spent those days thinking about those people.”

Patrik claimed that she recognized concepts from letters her husband David Kaczynski had received from his brother in the text that contained similar-sounding thoughts. After the family finally made the decision to inform the FBI, Kaczynski was eventually taken into custody in his Montana cabin on April 3, 1995 by a 9-man SWAT team.

“When she said, ‘Well, I think maybe your brother’s the Unabomber,’ I thought, ‘Well, this is not anything to worry about. Ted’s never been violent. I’ve never seen him violent,'” David Kaczynski said in the interview. “I couldn’t imagine that he would do what the Unabomber had done.”