Theodore Kaczynski, who confessed to waging an 18-year campaign of terror as the "Unabomber" in return for life in prison, will be formally sentenced May 4, officials said Friday.

The sentencing, the result of a plea bargain that ended his trial abruptly on Jan. 22, had been scheduled for May 15 but was advanced after probation officers completed their evaluation report early.Kaczynski, a former university math professor whose series of package and letter bombs killed three people and injured 29 between 1978 and 1995, has been held at Sacramento County Jail since he reluctantly agreed to plead guilty to escape a possible death sentence.