Who is the Long Island serial killer?

New details: The search for Shannan Gilbert leads to the discovery of the bodies of four other women on Gilgo Beach.

The Long Island Serial Killer 41:15

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.

So far, police can't connect these latest remains to the original four. In fact, 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: Baby girl wrapped in a blanket

Victim No. 8: Asian man in his 20s

Victim 9 [and maybe 10]: A skull and a bag of human bones

As many as 10 bodies found in the scrub brush on Long Island and none of them belongs to Shannon Gilbert. So where is she?

"Do you think the clue to the serial killer is in Shannan Gilbert's disappearance or is it just a coincidence?" Erin Moriarty asks Suffolk County Police Commissioner Richard Dormer.

"We don't know. She doesn't fit the pattern," he replies. "But it's still part of the investigation and we're certainly open to every possibility."

The search for Shannan began in the last place she was seen: the gated community of Oak beach, just three miles from the dumping ground.

The police started looking at 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.

"When the bodies were found, obviously, he was somebody they wanted to speak with," Newsday crime reporter Andrew Strickler explains. "They searched his house...they searched his car."

Although Brewer refused to go on camera, he did meet with "48 Hours." He admitted soliciting Shannan online, but he said not for sex.

"Do you find that credible?" Moriarty asks Robin Sax, the Gilbert family's attorney. "That Joseph Brewer says that he just wanted companionship and...that he never intended to pay her? He just had her come over to his house?"

"You don't need someone to come [at] 1:00 in the morning to your home...and not expect to have some sort of sex act, and not to pay at the end," sax says. "It's ludicrous."

Especially since Shannan was booked for two hours but stayed an hour longer.

"So presumably she was trying to make more money. She was trying to make more out of her time on Long Island," says Sax.

But Brewer himself admits he refused to pay what she asked for and they got into an argument. And shortly afterwards, she made that panicked call to 911 from inside his house.

Sax is convinced Shannan felt threatened. "The fact is she called 911. She said, 'They're going to kill me.' She was scared for her life...and she's never been seen since."

Brewer insists he never harmed Shannan. He just wanted her to leave. In fact, he brought her driver in to get her out of there. He says the last time he saw her, she was running out of his house towards 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 [and] would stop and then go a little bit. Stop, go a little bit," says Colletti.

It turns out she seemed to be running from the man who was supposed to be protecting her, the second man police wanted to talk to: her driver, Michael Pak.

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

"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.

"If you are the driver and you are responsible for this girl's transportation back home, you would think you'd give it a little more than an hour. At least to wait until the police came to force them to start looking together to be able to find her," says Sax.

Michael Pak is another odd character in this strange story. He's a dog owner — obsessed with his pet Chihuahuas, dressing them up in YouTube videos.

But Michael Pak is also a convicted felon, having served time in federal prison for conspiracy to misuse a passport.

"Michael Pak has his own checkered history," Sax explains. "He was arrested...for bringing in a Chinese lady to the United States."

Pak told "48 Hours" he had nothing to do with Shannan's disappearance and claimed he passed a polygraph "with flying colors." Police wouldn't confirm or deny that.

And then there's the third man, a total wildcard: A neighbor and retired emergency services doctor named Peter Hackett.

"Dr. Hackett is a curious character," Sax says. "He's someone whose involvement, while we can't necessarily understand, is bizarre enough that makes you wonder, what is his connection to the case?"

Just days after Shannan went missing, her sister, Sherre, says their mother got a strange call from a man they had never heard of — Dr. Hackett — who, she says, claimed he found Shannan roaming around Oak Beach the night she disappeared and brought her into his home.

"So he called my mom and he said that he saw Shannan, he held her at his house and following morning, the driver came back to pick her up and that was it," says Sherre Gilbert.

But when the sisters made their trip to Oak Beach to find out more, Dr. Hackett denied that he ever met Shannan.

"And at that point, we were just really upset," Sherre says. "We didn't know what to believe."

In press reports, Hackett denied making any call.

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

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

And 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 any way.

The police tell "48 Hours" that Hackett and the other two men cooperated fully and are not suspects. They also said they are not closing any doors and the investigation remains wide open.

"This case has turned into a case that's tangled with lies where I still believe there are many secrets that are yet to be uncovered at Oak Beach," says Sax.