By Jill Smolowe
May 09, 2011 12:00 PM

For a week after New York City prostitute Melissa Barthelemy disappeared from her Bronx apartment in July 2009, police seemed intent on talking her anxious family out of filing a missing person’s report. “They said, ‘She’s 24; she’s where she wants to be; she’s not missing,’ ” recalls her mother, Lynn. Authorities stepped up their investigation more than a week later when Melissa’s teenage sister began to receive a series of seven creepy phone calls from an unknown man, all of them placed from the missing woman’s own cellphone. During his final call, says Lynn, “He said, ‘I killed Melissa.'”

Ten months passed, then Shannan Gilbert, a prostitute from nearby New Jersey, went missing after fleeing the Long Island home of a customer she met on Craigslist; by the time police arrived, Shannan was nowhere in sight. Seven months later, while combing highway brush for Shannan, 24, near the upscale town where she’d last been spotted, investigators stumbled across the bodies of four young women; Shannan’s was not among them, but Melissa Barthelemy’s was. And they were all prostitutes who had advertised on Craigslist and had been missing for months or even years.

Galvanized by the chilling prospect that a serial killer-or killers-might be stalking Long Island, investigators beefed up their search teams. In recent weeks they have unearthed the remains of six more bodies along the same brambly five-mile stretch of desolate beachside highway. “You have a serial killer,” Vernon Geberth, author of the textbook Practical Homicide Investigation, says flatly. “Prostitutes are probably the most common victims of serial killers.”

And, relatives fear, among the easiest to write off as unworthy of either police attention or public sympathy. Yes, Shannan was a call girl, says her aunt Lori Grove, “but does that mean she wasn’t worth looking for all those months?” Grove adds that despite Shannan’s “tumultuous childhood,” involving stays in several foster homes, she was so gifted a student that she graduated from high school at 16. Shannan also loved to cook. “She’d say, ‘I got it, Mom; go watch TV,'” says her mother, Mari Gilbert, 46, who works at the Walmart in Middletown, N.Y. Shortly before disappearing, Shannan moved into an apartment of her own in Jersey City, N.J. “She was taking some online courses,” says Sherre, 23, one of Shannan’s three younger sisters. “You felt like maybe she was getting it together.”

The Barthelemy family similarly believes Melissa had only turned to prostitution as a temporary stopgap. After high school, she earned a cosmetology license and moved to New York. Though she told her parents that she was working as a nightclub dancer, she leveled with her sister Amanda, 17, about her involvement in prostitution. “She said she was doing it because the money was good, and she was trying to save because she wanted to open her own salon,” says her mom, Lynn, who runs a diner in Cheektowaga, N.Y. Had she known the truth, Lynn adds, “I would have made her pack up and come home.”

As investigators continue to comb nearby waters and land for both Shannan and more remains, they discount media reports that the killer had such a savvy knowledge of how to avoid detection that he might himself be in law enforcement. But, says Lt. Kevin Smith of the Nassau County Police, “There is no suspect as far as we know.” Families of the deceased, meanwhile, have found each other on Facebook. “There’s comfort in knowing that someone else knows what you’re going through,” says Kim Overstreet, whose sister Amber Lynn Costello, 27, was among the four women discovered in December. “Someone knows your pain.” Certainly, Elmer Barthelemy, Melissa’s grandfather, understands. Shortly after Melissa’s disappearance, his wife died-a death Elmer, 64, attributes to grief. “I just want to let other girls who are out there like Melissa was know that no matter what they are doing, they’ve still got a family,” he says. “Please get out of the business and go home.”