The girlfriend of a man dubbed the "preppie killer" pleaded guilty Thursday to selling cocaine in a deal that sends her to a drug rehabilitation center.

Shawn Kovell, 41, admitted in state Supreme Court that she and Robert Chambers sold narcotics to an undercover detective last August.

Justice Charles Solomon told Kovell that if she completes the program, he will let her withdraw the guilty plea and plead to a lesser charge so she can receive a sentence of probation.

Kovell had been jailed until Thursday. Nothing in the plea agreement requires Kovell to testify against her boyfriend, according to her lawyer.

Kovell and Chambers were arrested at the Manhattan apartment they shared on Oct. 22 on charges of possessing and selling cocaine. Her lawyer, Frank Rothman, said at the time she was a drug addict and it was her first arrest.

Chambers, who is jailed without bail, has pleaded not guilty to the drug charges. His lawyer has said he plans to present a psychiatric defense to fight charges that could send him to prison for life.

Chambers, 41, became tabloid fodder in 1986 after the death of Jennifer Levin, an 18-year-old graduate of the exclusive Baldwin School, during a tryst in Central Park. The slaying was splashed across the headlines as the story of a handsome, privileged, prep school youth gone bad.

Chambers pleaded guilty in 1988 to manslaughter and was released from prison in 2003 after serving the maximum 15 years because of discipline problems behind bars, including dealing drugs.

A year after his release from prison, police arrested him for misdemeanor heroin possession and unlicensed driving. He pleaded guilty and was sentenced to 100 days in jail and fined $200.