(NEW YORK) -- Ted Kaczynski, the convicted terrorist known as the Unabomber, was found dead in his prison cell Saturday morning, according to a Federal Bureau of Prisons spokesperson. He was 81.
Kaczynski was previously in a maximum security facility in Colorado but was moved to a medical facility in North Carolina in December 2021 due to poor health.
Kaczynski, who went nearly 20 years without being captured until his arrest in 1996, was considered America's most prolific bomber.
Between 1978 and 1995, Kaczynski placed or mailed 16 bombs that killed three people and injured 23 others, according to authorities.
In 1995, before he was identified as the Unabomber, he demanded newspapers to publish a long manuscript he had written, saying the killings would continue otherwise. Both the New York Times and Washington Post published the 35,000-word manifesto later that year at the recommendation of the U.S. Attorney General and the director of the FBI.
If it hadn't been for the suspicions of his brother and sister-in-law, Kaczynski might never have been caught. Kaczynski's sister-in-law, Linda Patrik, was one of the first to identify Kaczynski as the Unabomber after reading the Unabomber's writing.
In an interview with "20/20 on ID Presents: Homicide" in 2016, Patrik recalled the first time she suspected Kaczynski was responsible for the serial bombings.
"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 said she recognized familiar-sounding ideas in the manuscript from letters her husband David Kaczynski had received from his brother. The family eventually decided to contact the FBI, and on April 3, 1995, a 9-man SWAT team apprehended Kaczynski in his cabin in Montana.
"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."
Ted Kaczynski went on trial in Sacramento, California, where the key issue was not his guilt but his sanity and whether he would be spared the death penalty. He pleaded guilty to murder in exchange for life in prison without parole in 1998.
This is a developing story. Please check back for updates.
Copyright © 2023, ABC Audio. All rights reserved.