June 23, 2012 10:48 PM

Was Shannan Gilbert a victim of the Long Island serial killer?

In March 2011, three months after finding the bodies of Melissa, Amber, Megan and Maureen, police start finding more bodies and more body parts along a once pristine beach playground; Six new sets of human remains in all.

Police believe the latest victims were linked to the sex trade, but only one has even been identified:

Victim No. 5: Jessica Taylor, an escort missing since 2003; dismembered

Victim No. 6: Jane Doe; dismembered.

Victim No. 7: A baby girl; possibly Jane Doe's

Victim No. 8: An Asian man dressed in women's clothes

Victims 9 and 10: A female skull and a bag of female

bones

Ten bodies... and none of them Shannan Gilbert. At this point, she had been missing for 10 months.

Her mother, Mari, and sister Sherre desperately tying to hold onto hope.

"I just did not want to believe that she wasn't ever gonna come home," said Mari.

"I knew that it was a possibility but I really just wanted to keep hope," said Sherre.

Photos: Crime scene and victims

The search for Shannan led police back to the last place she was seen:

The gated community of Oak Beach, just three miles from the dumping ground and to three men -- the man who hired her, the man who drove her and a doctor who put himself in the middle of the investigation.

Their stories are bizarre and confusing, starting with Joseph Brewer's - the john.

Although Brewer refused to go on camera, he did meet with "48 Hours."

He admitted soliciting Shannan online, but he said not for sex.

"So why did he pick, you know, a sex worker if he didn't want sex?" asked John Ray, the Gilbert family attorney.

Brewer claims he doesn't know what set Shannan off or why she made that call to 911. He says her fears were imagined. Attorney John Ray says they were real.

"When she made that call, do you believe she thought she was, her life was in danger?" Moriarty asked.

"No question she thought her life was in danger," replied Ray.

Brewer says he never harmed Shannan. He says he just wanted her out of his house and even brought the driver in to get her to leave. He can reportedly be heard on the 911 tape saying he was going upstairs. He says the last time he saw Shannan, she was running out of his house toward his neighbor's.

That neighbor, Gus Colletti is the one who tried to help Shannan and noticed that black SUV following her.

"I could see a car coming down the road very slowly with -- would stop and then go a little bit. Stop, go a little bit," said Colletti.

In that car was Michael Pak, Shannan's driver - the second man police wanted to talk to.

"I ran up to his car and I said to him, 'Where do you think you're going?'" said Colletti.

Pak told Colletti he was looking for Shannan.

"I said, 'Well, I called the police... they are on their way to bring her back," Colletti said. "He said, 'You shouldn't have done that.' I said, 'Well, I did.'"

Pak, who also wouldn't go on camera, told "48 Hours" he drove around looking for Shannan for about an hour. He couldn't find her, he says. So he left.

The more you learn about Michael Pak, the stranger he becomes.

On one hand, he's obsessed with his pet Chihuahuas, dressing them up in YouTube videos. On the other hand, he's driving Shannan Gilbert to meet her johns.

And clearly, he was inside Brewer's house when she made that call to 911.

"She says things like, 'Stop it. Stop it.' And you can hear the driver's voice saying, 'Fine, fine, fine,' words to that effect," said Ray.

In a text message, Pak admits to being inside the house during the call. Although he texts that Shannan was in "a paranoid state" he believes it was calculated -- "she was actually coherent and just acting crazy because she didn't want to pay me my cut."

He also says he "never touched her" and maintains that he had nothing to do with Shannan's disappearance.

And then there's the third man, a total wildcard: A neighbor and retired emergency services doctor who inserted himself in the middle of the mystery: Peter Hackett.

"Dr. Hackett came into this case almost immediately after the disappearance of Shannan. How? Well Dr. Hackett telephoned Mari Gilbert," Ray explained.

At the time, Mari says she didn't even know her daughter was missing.

"I received a call from a man who said his name was Peter Hackett and told me that Shannan was at his house, that he ran a halfway house for people who wanted to get off the street and that Shannan was there," she said.

Mari says Hackett then told her that Shannan left his house with Michael Pak and he never saw her again. But when Shannan's sisters made their trip to Oak Beach, Dr. Hackett told a different story.

"He denied calling my mother," she told Moriarty.

"Had he seen Shannan?"

"He said he never saw Shannan before."

"What did you think?"

"I thought that he was a liar and I still think he's a liar," Sherre said.

"You didn't think your mom could be mistaken?"

"I was there when my mother received the phone call, so there's no way."

Hackett denied making that call in press reports as well. Police learned otherwise.

"Do you believe that he called her mom? Moriarty asked former Commissioner Dormer.

"Yeah. Our information is that he did," he replied.

In fact, in a letter to "48 Hours" dated June 28 2011, Dr. Hackett admits he made not one phone call - but two to Shannan's family.

Hackett writes: "These calls were over a year ago now and exact content is difficult to remember, but, at no time... did I suggest I had ever met her or render medical care of any sort to her."

Read Dr. Hackett's letters to "48 Hours"

Hackett says he got the telephone numbers from Shannan's friend who was searching for her in Oak Beach and says he called just to see if he could "help in anyway."

"Those facts that Hackett admits the he called twice, when he first denied it, are not rationally explainable unless he has a bad motive," Ray told Moriarty. "You cannot find a reasonable reason for that to have occurred, for the denial to have occurred."

The police tell "48 Hours" that Hackett cooperated fully and is not a suspect. But Ray thinks Hackett should have been looked at more closely...He also thinks the same about Michael Pak and Joe Brewer.

"I don't know who killed her. I mean I can't say that any one of those three men actually did it. But you can say that at this stage all three of those people have put themselves in this inner circle of suspicion. How could you avoid that?" said Ray.

As with Hackett, the police said Pak and Brewer are not suspects. They also said they are not closing any doors and the investigation remains open.

Meanwhile, Shannan's family continues to wait for answers that never seem to come.


© 2012 CBS Interactive Inc. All Rights Reserved.
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