Theodore "Ted" Kaczynski, the man known as the "Unabomber," has died, according to a law enforcement official.

Kaczynski had been serving eight life sentences after he pleaded guilty in 1998 for sending bombs that killed three people and wounded 23 others through the mail from 1978 to 1995.

The Harveard-educated former math professor was arrested in 1996 at a small, remote cabin in western Montana.

In 2021, Kaczynski was moved to a federal medical center in North Carolina, according to the Federal Bureau of Prisons. He had been held at Supermax in Florence, Colorado, before he was transferred to FMC Butner on December 14, 2021.

Portrayed by prosecutors as a vengeful loner, Kaczynski published 30,000-word treatise that became known as the Unabomber Manifesto.

In the document, Kaczynski claimed a moral high ground for his deadly campaign, justifying the attacks in the name of preserving humanity and nature from the onslaught of technology and exploitation.

"I believe in nothing," Kaczynski wrote. "I don't even believe in the cult of nature-worshipers or wilderness-worshipers. (I am perfectly ready to litter in parts of the woods that are of no use to me -- I often throw cans in logged-over areas.)"

A sentencing memorandum quoted extensively from Kaczynski's journals, in which he wrote of a deep hatred of people.

This is a developing story and will be updated.