Ted Kaczynski - the domestic terrorist more commonly known as the Unabomber - has been found dead.
BBC News reports that Kaczynski was found dead in his prison cell on Saturday. He was 81.
Kaczynski was being held at a federal prison medical facility in North Carolina after being sentenced to life in prison without parole back in 1996.
The sentencing came after Kaczynski - who had evaded police capture for almost two decades - pleaded guilty to killing three people and injuring 23 more via a series of mail bombings between 1978 and 1995.
At the time of his arrest, he was considered to be the most prolific bomber in US history - having placed or mailed a total of 16 bombs, per authorities.
Per ABC News, Kaczynski sent a manuscript to newspaper offices demanding he be referred to as the Unabomber - threatening to carry out more attacks if they refused.
His 35,000-word manifesto was later published in outlets such as the New York Times and Washington Post under the guidance of the U.S. Attorney General and the FBI director at the time.
Kaczynski was eventually caught following suspicions of his brother and sister-in-law, Linda Patrik.
Patrik said she was able to first identify Kaczynski thanks to his handwriting in the manifesto.
If it wasn't for these initial suspicions, he may never have been caught.
In a 2016 interview with 20/20, Patrik opened up about how the bombings impacted her, saying: "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 two-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.
"And there were others. And so I spent those days thinking about those people."
BBC News adds that Kaczynski had been suffering from declining health since December 2021.
Prior to being moved to the NC prison medical facility, Kaczynski had been held at the federal Supermax prison in Florence, Colorado.
Our thoughts go out to the victims of his crimes at this time.