Bringing justice to a homicide case that had gone unsolved for 18 years, a Philadelphia jury yesterday found Brian Hall guilty of third-degree murder in the 1987 slaying of Rosella Atkinson.

The verdict means the jury believed he committed the crime with malice but not the specific intent to kill.

Plagued by what he said were pangs of conscience after nearly two decades, Hall turned himself in, telling detectives "it's time to get right" for strangling the 18-year-old Nicetown woman in a field near Central High School after a night of drinking and possibly some sex.

His confession, in which he said he suspected Atkinson had taken some money from him and he became forceful when she refused to let him search her, is vague on other details.

Nontheless, Hall, 55, pled guilty. In an unusual proceeding, the jury was asked to determine his degree of guilt. At his sentencing, scheduled for Tuesday before Judge Shelley Robins New, Hall faces imprisonment for 10 to 20 years.

"We're glad a verdict was decided, but we're not pleased with the outcome. The crime that took place was not completely revealed," said Sandra Morris, a cousin of the dead girl, who said she hopes Hall will receive the maximum penalty.

Atkinson's partially clothed skeletal remains were found buried under leaves and branches about four months after her disappearance. The remains went unidentified until 1990, when her family went to an exhibition by forensic sculptor Frank Bender and saw what looked like Atkinson's face on one of his pieces.

Had Hall not come forward and confessed to police in September 2005, the circumstances of her death might still be a mystery.

In brief interviews after the verdict, both the defense and prosecution speculated that the jury may have been more lenient in determining Hall's culpability because of his late-in-life cooperation. Had the jury found that Hall committed first-degree murder, defined as a premeditated act with the specific intent to kill, he would be facing a life sentence.

"He came forward, almost played the good Samaritan," said Morris, shaking her head dismissively and angry that her cousin had been portrayed in court as "a slut" by the defense while Hall never took the stand to testify.

Assistant District Attorney MK Feeney said because Hall committed the crime in 1987, he faces the relevant penalty that was in place at that time. Had he committed the same crime today, she said, he would face 20 to 40 years in prison.

Contact staff writer Michael Matza at 215-854-2541