Accused Center City Rapist Troy Graves returned to Philadelphia last night, reportedly to plead guilty to the murder of Wharton School student Shannon Schieber in exchange for not getting the death penalty.

Yesterday, the Daily News reported that prosecutors here had offered to spare Graves' life if he revealed details about Schieber's murder that might help the city fight a civil suit filed by Schieber's parents.

That enraged Sylvester Schieber, who said yesterday his attorneys were considering taking further legal action against the city as a result of the story.

Sylvester Schieber said he was concerned that prosecutors in Philadelphia used the death penalty to force Graves to say what they want him to say.

"They're using this as leverage against us, and it's as crude and crass as anything they could do," he said.

Although the Schiebers have made it clear they do not want Graves executed, they said they also don't want authorities to use the death penalty as a bargaining tool to beat them in their suit.

Cathie Abookire, spokeswoman for District Attorney Lynne Abraham, did not return a call for comment yesterday about the case, including when Graves would enter a plea.

Dan Hopkins, spokesman for Colorado Gov. Bill Owens, said yesterday that Graves' return to Philadelphia did not require official extradition papers because he was just going to be here temporarily, which indicates he is going to plead guilty rather than face a trial. Afterward, he would return to Colorado.

Last Friday, Graves, 30, pleaded guilty to a rape spree in Fort Collins, Colo., and was sentenced to life imprisonment under a deal that allows him to serve his sentence in a Colorado prison.

That guilty plea was contingent on Philadelphia prosecutors' not seeking the death penalty against him. Abraham insisted last Friday that she had not agreed to such a deal but would not comment on whether she would agree to forego the death penalty in exchange for a guilty plea.

On Tuesday, Philadelphia prosecutors, defense attorneys, detectives and others met with Graves for hours at the Larimer County Detention Center in Colorado, where he provided details of Schieber's slaying, said Barbara Zollars, head of the Fort Collins branch of the Colorado public defender's office.

On arrival here last night in the company of homicide detectives, Graves was escorted to police headquarters at 8th and Race streets where he was officially charged with five sexual assaults and Schieber's rape-murder.

Shannon Schieber, 23, was killed May 7, 1998. Her parents sued the city after learning that police had been called to her apartment that night after a neighbor heard her screaming but that they had not broken into her apartment.

Whether Schieber was alive when cops knocked on her door is a key issue in the lawsuit.

Evidence does show that Graves was likely still inside when police arrived at her door. Before leaving that night, one cop shined his light on her second-floor apartment's balcony and noted that the sliding-glass door was closed. The next afternoon, when Sean Schieber found his sister dead in her apartment, the sliding-glass door was open.