New York law enforcement officials began searching a 15-mile swath of Long Island's most popular beachfront Friday as the investigation widened into the grisly discovery of the remains of four women, as authorities concluded that a missing New Jersey woman was not one of the victims.

Suffolk County, N.Y., investigators also were continuing to work with authorities in Atlantic City, N.J., to see if there is any connection to the 2006 murders of four prostitutes, a case that remains unsolved.

The Suffolk County Medical Examiner's Office released a statement late Thursday indicating that none of the bodies found on Gilgo Beach are that of Shannan Gilbert, 24, of Jersey City, N.J., who was reported missing in May.

A nearly 15-mile stretch of Ocean Parkway on Long Island has been closed until 3 p.m., authorities said.

Police were conducting a "training exercise" on Saturday when they came across the first body. A police canine unit chose the area in response to Gilbert's missing-person report. Three more badly decomposing female bodies were discovered on Monday.

Gilbert was reportedly last seen alive on May 1. The woman worked as a prostitute and had arranged through the Craigslist classified ads website to meet a client on Fire Island -- about a mile from Gilgo Beach, a police source told FoxNews.com.

Gilbert's mother, Mari Gilbert, found little solace in the news.

"I'm confused. Where is she?" Mari Gilbert told the New York Post from her home in Ellenville, N.Y. "I still miss her and I want her home, and she's still not here."

Police and FBI agents investigating the case raided a home on Long Island Thursday where Gilbert was last seen, sources tell FoxNews.com.

An official with the Suffolk County Police Department said a white sport utility vehicle was taken from an Oak Beach, N.Y., residence but declined to identify the owner.

The official -- who spoke on condition of anonymity due to an ongoing investigation -- also said authorities returned Thursday to the secluded quart-mile section of Ocean Parkway looking for more possible victims.

Authorities said they are hunting for a possible serial killer who may have dumped the women in area. The women's remains were found in different stages of decomposition, according to a police source, leading authorities to believe that they were dumped over the course of a year -- possibly even two years.

The women have not yet been identified.

Authorities have not released the name of the Oak Beach homeowner, but local news reports say Gilbert was last seen at the home of 46-year-old Joseph Brewer, a local businessman.

When FoxNews.com called a phone number registered to a Brewer family member, a man answered the phone and said "we have no information." He directed FoxNews.com to call the police with any questions.

The New York Post reports that Brewer invited Gilbert to his home for a party on May 1 after corresponding with her through Craigslist.com. The 24-year-old woman reportedly ran frantically from Brewer's home later that night, and banged on the door of neighbor Gustav Colletti, asking for help. Gilbert's mother also reportedly told the newspaper that her daughter called 911, saying, "He's trying to kill me! Help me!"

Coletti told the Post he always doubted Brewer was involved in the killings.

"What guy would murder four people and dump them right outside the door here? That would be a pretty stupid thing to do," Coletti told the newspaper. "I guess we'll see what happens."

Meanwhile, the mother of a Maine woman who worked as a Craigslist escort and went missing from a hotel on Long Island said police informed her that her daughter may be one of the victims.

Twenty-two-year-old Megan Waterman, of Scarborough, Maine, was last seen in June after arranging to meet a john in Suffolk County, the Post reports.

Waterman's mother, Lorraine Ela, told The Associated Press that a Scarborough detective told her he was "leaning toward one of the four victims being Megan, but he's not 100 percent guaranteed."

Waterman's mother supplied investigators with a DNA sample on Wednesday, but told the Post she had not heard anything since that time. Sources told the newspaper Waterman will likely be eliminated as well because the remains appear to date back further than last summer.

"You can imagine, this is a difficult case," Suffolk Police Commissioner Richard Dormer said. "I don't want anyone to think we have 'Jack the Ripper' running around Suffolk County with a knife dripping with blood."

Click here to read more on this story from MyFoxNY.com

Click here to read more on this story from the New York Post.

FoxNews.com's Cristina Corbin and the Associated Press contributed to this report.