TED KACZYNSKI, MORE commonly known by the alias ‘the Unabomber’, has died today in a US federal prison at the age of 81, American media has reported.

A spokesman for the Federal Bureau of Prisons told the New York Times that Kaczynski was found unresponsive in his cell in North Carolina early this morning.

The cause of death was not immediately known.

Kaczynski pleaded guilty to killing three people and injuring 23 more during a mass bombing spree between 1978 and 1995.

He was sentenced to life without parole in 1996 after evading capture for almost 20 years.

In 1995, Kaczynski sent a letter to the New York Times and Washington Post promising to “desist from terrorism” if they published his manifesto condemning modern technology.

After the “Unabomber Manifesto” as it became known, was published, Kaczynski’s brother recognised the writing style and informed the FBI, which eventually led to his arrest.

Kaczynski was accepted into Harvard University at the age of 16, before starting a career in mathematics and then choosing to live a hermit-like life in isolation in a cabin in Montana where he lived from 1971 until his arrest.