Ted Kaczynski, more commonly known as the Unabomber, was found dead in his prison cell last weekend, and his cause of death has been revealed.
Kaczynski, 81, terrorized the US for nearly two decades as he built untraceable bombs and sent them to random targets - killing three people and injuring 23 more, as per the FBI.
His crimes date back to 1978 when a passerby found a package in the car park of the University of Illinois which subsequently exploded on opening and injured a security officer.
For the next 17 years, the Unabomber evaded capture as he secretly mailed explosives across the country, including one pressurized bomb that filled the cabin of an American Airlines plane with smoke, but luckily it failed to go off as intended and the flight made a safe landing.
Having mailed or placed 16 bombs during his reign of terror, the Unabomber was considered to be the most prolific bomber in US history at the time of his arrest.
Following a tip-off from his brother and sister-in-law Linda Patrik, the Unabomber was arrested in 1996 and in 1998 he pleaded guilty to the series of bombings.
He was sentenced to life in prison without the possibility of parole and was held at the federal Supermax prison in Florence, Colorado.
In 2021, Kaczynski's health began to decline and he was moved to a federal prison medical facility in North Carolina, as reported by BBC News.
The Unabomber was found dead in his cell on Saturday, and it has since been confirmed that the domestic terrorist died by suicide, as per NBC News.
As is protocol, the state's chief medical examiner will conduct an autopsy. Kaczynski had been diagnosed with cancer, but its severity remains unclear.
The infamous name was coined by Kaczynski as he sent a manuscript to newspaper offices demanding that he be referred to as the Unabomber - threatening to carry out more attacks if they refused, per ABC News.
His 35,000-word manifesto was made public and it was this that was his undoing, as Patrik recognized his handwriting and turned him in.
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 at 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," she concluded.