A Prince George's County Circuit Court judge convicted a 20-year-old Langley Park man Tuesday of raping and assaulting a 77-year-old woman, then immediately sentenced him to life imprisonment.

Judge Perry G. Bowen Jr. said yesterday that he did not order the usual presentence investigation for Isaiah Fesaster because it would not have affected his decision about the punishment.

Feaster, of 8129 14th Ave., allegedly entered the Kanawha Street apartment of the elderly woman last March 23 while she was sleeping, made several long distance calls on her telephone without waking her, then cut her with a kitchen knife and raped her, according to Assistant State's Attorney Robert Matty.

Feaster, a maintenance worker at the apartment complex, apparently entered the apartment through an unlocked kitchen window at about 1 a.m. Matty said.

He then made long-distance phone calls to woman in Bronx, N.Y., Matty said, and talked to her for two hours and 15 minutes.

Police eventually traced Feaster through the victim's monthly phone bill, Matty said.

Feaster admitted making the calls, and told police he had touched the woman in bed, but denied that he had raped her, Matty said.

The woman, who is virtually blind, was initially taken to Washington Adventist Hospital, then was treated for two days at the Prince George's General Hospital's sexual assault unit, Matty said.

Matty said the woman did not suffer permanent injury