With tears dampening his cheeks, Center City rapist Troy Graves apologized yesterday to his Philadelphia victims and the family of slain student Shannon Schieber. Graves trembled as he was given his second consecutive life sentence.

"I wish I could offer more than an apology," Graves said, his voice cracking.

Graves, 30, begged for forgiveness - even pledging to open his soul to FBI profilers - after a draining hearing in which prosecutors detailed his methodical crime spree through Center City: how he sexually assaulted six women, throttling two of them, leaving one unconscious and Schieber dead after she fought him in a fierce struggle.

Yet even as Graves was apologizing to Schieber's parents, prosecutors released a confession from him with a statement that could prove damaging to the family's high-profile lawsuit against police over her murder.

That pending federal lawsuit contends that police who went to Schieber's apartment on the night of the attack missed a chance to save her life by not knocking down the door. The suit says Schieber was likely alive and in a struggle with her killer at the minute police were at the door. The officer knocked on the door, cried "police," but left after hearing no response.

But Graves, in his confession, said he never heard any knocks or cries from police officers.

Graves said he had killed Schieber and left before the officers arrived - making their conduct at the door moot.

In response, Sylvester J. Schieber, Shannon Schieber's father, said the family viewed that part of Graves' statement with "tremendous skepticism."

Before a packed courtroom, Graves pleaded guilty to the murder and rape of Schieber, and to the rape or attempted sexual assault of five other women. Those attacks, between 1997 and 1999, exposed the bungling of the Philadelphia police sex-crimes unit and remained unsolved until Graves' arrest last month in Colorado.

Common Pleas Court Judge Benjamin Lerner sentenced Graves to life in prison without parole plus 60 to 120 years. Those sentences are to follow the life sentence Graves received May 17 for seven attacks on women that began last year in Fort Collins, Colo. He will serve the sentence there and yesterday asked to be returned as soon as possible.

With the Philadelphia plea agreement that Graves signed on May 21 and formally entered yesterday, the Air Force airman avoided the death penalty and provided prosecutors with detailed accounts of the Philadelphia attacks.

Graves never turned to look at Vicki and Sylvester Schieber, Shannon Schieber's parents, in the first row, or at the rape victim who wept in the rear of the courtroom.

Instead, Graves, muscular and military-fit, stood rigidly and looked straight ahead, taking two deep breaths as tears began to run down his face.

"I want to give my deepest apologies to the Schieber family for their loss and to thank them once again for how they've been throughout this," Graves said.

Citing their devout Catholic faith, the Schiebers had repeatedly said they did not want Graves to be executed for the murder of their 23-year-old daughter, a Wharton School graduate student who was raped and slain in her second-floor apartment at 251 S. 23d Street on May 7, 1998.

Graves asked the Schiebers to judge him and his sincerity by what he does with the years in prison that lie ahead. He said he planned to speak with criminal profilers "to help future investigations and maybe myself."

His attorney, Assistant Defender Daniel Stevenson, said Graves had agreed to a request from FBI profilers to meet in August.

Stevenson said Graves told him that he wanted to get caught and that he did not understand why he attacked women.

"It's a mystery to him," Stevenson said after the hearing. "He had this constant battle with himself."

During the hearing, Stevenson turned to the Schieber family and made an unusual statement of thanks for their public opposition to the death penalty for Graves.

"I just want to publicly acknowledge the generosity of the Schiebers' spirit... against a rising tide of blood lust in this city. They have said, 'No more killing,' " Stevenson said.

But during a hard-edged news conference yesterday, District Attorney Lynne M. Abraham said that although justice was served with Graves' plea, she still believes that execution would be the most appropriate penalty for him.

"I'm satisfied with the outcome because it puts an end to the suspense of who the Center City rapist is," Abraham said. "Troy Graves - if I have anything to do with it - will never walk as a free man on this earth again. The only way he will leave prison is feet first."

During the hearing, Graves' second victim sat tensely in the back of the courtroom. The victim, who was unconscious during the July 1997 attack and awoke to find herself naked and bruised, only recently learned from authorities that Graves had acknowledged he had raped her.

Police had initially classified her case as a burglary and not as a sexual assault.

When Assistant District Attorney Arlene Fisk read aloud Graves' description of his attack on her, the petite 30-year-old broke into muffled sobs and leaned on her boyfriend, who was sitting next to her.

"It was what I was hoping, what I was expecting," the victim said after the hearing. "I'm glad it's over."

The Schiebers and their son, Sean, who discovered his sister's lifeless and nude body on her bed, blanched in the courtroom as Fisk recounted Shannon Schieber's desperate struggle against her attacker.

"It was awful. She was the love of my life and she was everything to me," Vicki Schieber said after the hearing.

For the first time yesterday, prosecutors released Graves' version of how he killed Shannon Schieber.

Graves told detectives he raped Schieber after climbing through the sliding-glass door on her balcony and surprising her in her bathroom.

After the rape, Graves said, Schieber began to struggle against him, scratching his face and biting his left ring finger until he bled.

Graves said he put his arms around her neck in an attempt to subdue her. But at one point, she fell off the bed as he was holding her around the neck.

"I countered by jumping back on the bed, onto my knees, which didn't allow her feet to touch the floor," Graves told detectives. "OK, it was at that point that I thought I might have broken her neck."

He said he heard someone knock on the door two separate times - pounding from a worried neighbor who had heard a struggle - but did not hear a third knock from police.

In the transcript provided by prosecutors, homicide detectives elicited statements from Graves saying that not only did he not hear the police knock, but he saw no evidence of police as he fled the apartment through the balcony door.

In response to questioning from detectives, Graves also said he closed the balcony door after he left - a key piece of evidence for the lawsuit.

Though the door was closed when police arrived on the night of the murder, Sean Schieber said he found the balcony door open when he discovered the murder. The Schiebers have argued that the fact that the door was closed at night but open the next day suggested that Graves was still inside the apartment when police arrived.

At the news conference yesterday, Abraham presented a new explanation - that Sean Schieber opened the door himself because he was sick at the sight of his sister's body.

"That's just absolutely preposterous," Sean Schieber said angrily last night, adding that he noticed the open door from outside, before he entered the apartment, and that he never went near that door.

A friend of Sean Schieber's who was with him at the time they discovered Shannon Schieber's body has said in deposition that before entering the apartment, she also noticed that the door was open.

Stevenson, a member of the Defenders Association death-penalty unit, yesterday described Graves' demeanor and said it baffled both him and veteran homicide detectives.

"He's a complex, complicated young man," Stevenson said. "He's an aberration. You meet this engaging and friendly young man, and it doesn't compute with the awful things he did."

Graves' arrest followed years of missteps and embarrassments by the Philadelphia police, including lengthy delays in testing DNA evidence to see whether the initial rapes were linked.

Because investigators failed to detect the pattern in Graves' attacks, citizens were unaware that a serial rapist was targeting women in Center City.