Ted Kaczynski, also known as the Unabomber, has died at the age of 81.  

Branded the ‘Unabomber’ by the FBI, Mr Kaczynski was found unresponsive in his cell early on Saturday morning.  

A Bureau of Poisons spokesperson said he died at the federal prison medical centre in Butner, North Carolina. 

Before his transfer to the prison medical facility, he had been held in the federal Supermax prison in Florence, Colorado, since May 1998, when he was sentenced to four life sentences plus 30 years. 

The Harvard-educated mathematician waged a 17-year bombing campaign which killed 3 people and maimed many others. 

Mr Kaczynski largely targeted academics, scientists and computer store owners and attempted blow up a commercial airline, prompting the FBI to dub him the Unabomber (‘University and Airlines Bomber’). 

CAAG2N May 01, 2003; Sacramento, CA, USA; The 10' x 13' wooden cabin that Ted Kaczynski, the convicted Unabomber, lived in in Montana has been transfered to private ownership today, Thursday, May 1, 2003. The structure was supposed to be dismantled and removed from a storage facility at Mather Regional Pa

His actions changed the way Americans mailed packages and boarded airplanes.

His published 35,000-word manifesto claimed modern society and technology was leading to a sense of powerlessness and alienation. 

The Unabomber was discovered after his brother recognised the tone of the manifesto and tipped off the FBI.  

He was discovered and arrested in a cabin in Montana that was filled with journals, a coded diary, explosive ingredients and two completed bombs. 

2PFEJK8 Suspected Unabomber Theodore Kaczynski looks around as U.S. Marshals prepare to take him down steps at the federal courthouse to a waiting vehicle Friday, June 21, 1996 in Helena, Mont. A federal judge Friday ordered Kaczynski moved to California to face charges that he is the Unabomber. (AP Photo/Elaine Thompson)

Mr Kaczynski admitted to committing 16 bombings from 1978 and 1995, permanently maiming several of his victims. 

Psychologists reported Mr Kaczynski was motivated by "his belief that he is being maligned and harassed by family members and modern society".

While before his capture many had sympathies for the Unabomber, Mr Kaczynski himself said he did not begin the bombing campaign for humane reasons.  

“I certainly don’t claim to be an altruist or to be acting for the ‘good’ (whatever that is) of the human race,” he wrote on April 6th, 1971. “I act merely from a desire for revenge.”