Theodore Kaczynski plotted killings years before the first Unabomber attack and fantasized about victims from his desire for revenge, prosecutors said Tuesday.
Kaczynski was driven not by his hatred of technology, but by his hatred of people, they said.
In a 34-page sentencing memorandum that quoted extensively from Kaczynski's writings, the government told a U.S. district judge that the former mathematics professor was a mentally alert, even brilliant, calculating killer who simply wanted to find victims. His court-appointed attorneys have described him as mentally ill.
He was writing about killing when he was a graduate student in Michigan in 1966, prosecutors said. He later taught at the University of California and then moved to Montana in the early '70s.
"I act merely from my desire for revenge," Kaczynski wrote in April 1971. "I believe in nothing."
The vivid portrait included a document described by prosecutors as a handwritten autobiography that showed Kaczynski angry from an early age.
In exchange for the guilty plea, the agreement calls for Kaczynski to be imprisoned for life.
While the sentence already has been decided, the memo was prepared so that the public may have a full accounting of his crimes, said a spokeswoman for the Unabom Task Force.
Kaczynski, 55, pleaded guilty to 13 counts that included the bombing deaths of three people.