THE VETERAN DETECTIVE WHO LED THE LONG ISLAND SERIAL KILLER INVESTIGATION SPEAKS OUT FOR THE FIRST TIME ON NETWORK TV, WITH NEW INFORMATION INTO THE DEATH OF SHANNAN GILBERT - ON "48 HOURS: LONG ISLAND SERIAL KILLER" SATURDAY, JULY 20, 2013, 10:00 PM, ET/PT

Erin Moriarty uncovers new information into the death of Shannan Gilbert and the veteran detective who ran the Long Island Serial Killer investigation speaks out on network television for the first time on 48 HOURS: "Long Island Serial Killer," to be broadcast Saturday, July 20, 2013 (10:00 PM, ET/PT) on the CBS Television Network.

In this new broadcast, Moriarty reveals new for details of a 911 call Gilbert made before she vanished in Oak Beach, N.Y. Moriarty reveals how Gilbert's call was directed to the New York State Police because Gilbert was panicked and couldn't tell police exactly where she was. It took a month before her call was tied to a missing persons report filed by her family in New Jersey, where she lived, and in that time evidence was lost. Moriarty also talks with a man who has inserted himself into the police investigation.

Gilbert, an online escort, went missing in May 2010. Her skeletal remains were found in a Long Island marsh in December 2011, and her clothes were found a quarter of a mile away. The search for Gilbert led to police finding a serial killer's graveyard.

Before she vanished, Gilbert made a desperate, early morning 911 call from inside a client's home. Former Suffolk County Chief of Detectives Dominick Varrone spoke with 48 HOURS about what authorities believe were her last hours alive.

"She's saying, 'there's someone after me, there's someone after me,'" Varrone says of Gilbert's call. "It's a girl who clearly believes she's in harm's way." Varrone adds that there are two male voices in the background - Shannan's driver, Michael Pak, and the man who hired her, Joseph Brewer. Brewer is heard in the background trying to get her to leave the house, Varrone says. "He either approaches her or touches her," Varrone says. "You hear her scream out."

Still on the phone, Gilbert fled the home and ran to the Oak Beach home of Gus Colletti. She was acting irrationally, but kept saying, "help me, help me." When Pak got there, she took off toward another home. Colletti called 911. When police arrived Gilbert was gone. In the call Gilbert never explains exactly who she was afraid of, and police say neither Pak nor Brewer are suspects in her death.

Moriarty also talks with Dr. C. Peter Hackett, an Oak Beach resident, who called Gilbert's mother two days after she went missing. Gilbert's mother, Mari Gilbert, tells 48 HOURS Hackett told her Shannan was at a halfway house he operated from his home. Hackett initially denied making the call, but later admitted in a letter to 48 HOURS he did call at the request of friends who were searching for Gilbert, and to be "supportive." He has steadfastly denied Mari Gilbert's account of their conversation and insists he never saw Shannan Gilbert or treated her.

Also for the first time ever, 48 HOURS will broadcast a portion of a confrontation between Shannan's mother and Dr. Hackett, videotaped by a friend of Mari Gilbert.

Varrone says Hackett is not a suspect in Gilbert's death. "He's an individual who likes to get involved," Varrone tells Moriarty. "Some call him a storyteller and an exaggerator. We certainly believe he may have called to offer his assistance."

Gilbert's death hasn't been tied to the Long Island Serial Killer, but there are similarities. Like Gilbert, many of the others found dead were escorts.

"The story of these women is the story about part of America, where people have few options and where some people make desperate or risky decisions," says Robert Kolker, author of the new book, "Lost Girls: An Unsolved American Mystery." Kolker tells Moriarty the Internet has made prostitution more accessible and dangerous. "It's easy for a killer to go shopping."

But what happened to Shannan Gilbert? The medical examiner could not determine a cause of death. Police believe she died accidentally when she ran into a Long Island marsh.

48 HOURS: "Long Island Serial Killer" is produced by Clare Friedland and Liza Finley. Greg McLaughlin is the producer-editor. Gary Winter and Marcus Balsam are the editors. Linda Martin is the update producer. Judy Tygard is the senior producer. Susan Zirinsky is the senior executive producer.

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