John Thomas Cobey, who raped a Silver Spring neighbor and then slit her throat last spring while on parole for rape and robbery, has been sentenced to two consecutive life sentences.

Montgomery County Circuit Court Judge John J. Mitchell, noting that Cobey had been free on parole less than a year at the time of his arrest, imposed maximum sentences Tuesday for first-degree murder and first-degree rape in the death of Debra Julia Donaldson.

Cobey, 25, pleaded guilty to those charges shortly after his arrest, and furnished details of the incident in a tape-recorded interview with a psychiatrist last month. He permitted his attorney, Thomas B. Cooke, to play the 45-minute tape in court before he was sentenced. Cooke unsuccessfully urged Judge Mitchell to impose concurrent penalties.

On the tape, Cobey, who lived in the Snowden Ridge town house development in Silver Spring, said he encountered Donaldson, a next-door neighbor, about midnight on April 15. He said he and a group of friends had gone out for beer after watching, for the second straight night, a videotape of the movie "Chain Saw Massacre" at the home of another neighbor. Cobey said he had locked himself out of his house and had gone to the rear of the residence to toss rocks at a bedroom window to wake his mother.

While at the rear of the house, Cobey said he saw a light in the complex's laundry room. Donaldson, 29, a divorced mother of three who was engaged to be married, had put her children to bed and was doing the family wash, according to court records.

Cobey said he was standing outside the laundry room door when Donaldson opened it. Startled, she attempted to shut the door, but Cobey said he forced his way into the room.

Donaldson, who worked as a supermarket clerk, was forced to take off her clothes and was then raped, Cobey said on the tape. Toward the end of the assault, Cobey said Donaldson began to scream loudly. At that point, he said he choked her into unconsciousness, then slit her throat with a knife to prevent her from identifying him later.

Donaldson's body was found face down near a basket of her family's laundry, according to police reports on the case.

Cobey, who was arrested the next day, was convicted in 1976 for entering another woman's home and attempting to rape her in her bedroom, according to court records. In that case, Judge John McAuliffe sentenced Cobey to two concurrent 10-year sentences.