ABC News In-depth Feature

It has been nearly 10 years since police were searching for a missing sex worker, Shannan Gilbert, and made the grisly discovery of 10 other bodies on a stretch of beach on the south shore of Long Island -- a chilling revelation that shook the greater New York area and made national headlines.

To this day, mystery shrouds the cases. The killer (or killers, by some accounts) has not yet been caught and five of the victims have not been identified. The way in which the victims who were identified, most of whom police say were sex workers, were killed is still not clear, but a Suffolk County police spokesperson told ABC News investigators are working under the assumption that a serial killer is to blame in some, if not all, of the killings.

And while police do not believe Gilbert's death is connected to the other murders, questions remain about how she died. A lawyer for her family, in fact, believes that she may also be a victim of the possible serial killer, based on an independent autopsy that could not rule out strangulation.

"Unquestionably, I believe it's a homicide," Gilbert's family lawyer, John Ray, told ABC News.

Suffolk County police recently released new evidence in the investigation of the deaths, which are being treated as one case, and announced the launch of a website dedicated to providing updates and collecting tips, in hopes of coming closer to solving the murders.

Yet even with the newly-released piece of evidence -- a photograph of a belt that was collected at the initial stage of the investigation but was withheld from the public -- many questions remain unanswered.

Here's what is known, and unknown, about the murders.

Bodies are found

On Dec. 11, 2010, authorities were searching in a weedy area off Ocean Parkway, which runs through a remote stretch of beach on a barrier island between Jones Beach and Robert Moses State Park, for Shannan Gilbert, a 24-year-old sex worker from New Jersey who had been missing since May of that year. Police did not find Gilbert during that search but found the remains of a woman later identified as 24-year-old Melissa Barthelemy.

Two days later, during another search in the same area, authorities found the bodies of three more victims: Amber Lynn Costello, 27, Megan Waterman, 22, and Maureen Brainard-Barnes, 25.

Three months after that, in March 2011, the remains of 20-year-old Jessica Taylor were also located near Gilgo Beach. Other parts of Taylors body had been found nearly eight years before in Manorville, New York (about an hour further east).

An aerial view of police cars near where a body was discovered in the area near Gilgo Beach and Ocean Parkway on Long Island, April 15, 2011, in Wantagh, New York.

All the women who were identified worked as prostitutes, police have previously said.

Three more bodies -- an unidentified woman, a 2-year-old girl and an unidentified Asian male believed to be between 17 and 23 -- were found April 4, 2011.

A week later, the last two of the 10 victims were found in neighboring Nassau County, including the toddler's mom.

All of the remains were discovered in the search for Gilbert and in relatively close proximity to each other along Ocean Parkway. Some were found as close as .5 miles of one another.

Gilbert's remains were finally found in December 2011 in nearby Oak Beach, which is also along Ocean Parkway. Police do not believe her death is tied to the others because she "doesn't match the pattern of the Gilgo Beach homicides," but have also said that her death is part of the active investigation into the Gilgo Beach murders, Suffolk County Police Commissioner Geraldine Hart said at the Jan. 16 press conference announcing the newly-released evidence. Gilbert's family lawyer believes that she is a victim of the possible serial killer.

Attorney John Ray has long been fighting to determine exactly what happened to Gilbert and believes police are hiding information regarding her death.

Police have not said exactly how the Gilgo Beach victims died.

The circumstances surrounding Gilbert's death also remain unclear.

The late Suffolk County Police Commissioner Richard Dormer initially suggested that her death was an accidental drowning. However, former Chief Medical Examiner of New York City Dr. Michael Baden who conducted an autopsy for the family in 2016, did not rule on her cause of death, but indicated that she may have died by strangulation, according to reports at the time.

The assertion was made because of the condition of the hyoid bone in her neck, which is commonly found broken in strangulation cases, Baden said, according to those reports.

"There is no evidence whatsoever that Shannan Gilbert died a natural death," Ray said in 2016.

Gilbert disappeared after making a 911 call to authorities at the home of a new sex client and screamed, "they are trying to kill me," according to Ray, who says he was briefed on the call by police sources and Baden.

Police have said that Gilbert began "acting irrational" during her encounter with the new sex client, who contacted a driver to have Gilbert leave his home.

Gilbert refused repeated attempts to leave the location with her driver and instead fled on foot, knocking on several doors in the community before disappearing, according to police.

Ray told ABC News police have refused to release the tape, citing an active criminal investigation into Gilbert's death.

Yet he also said the notion that there is a criminal investigation into Gilbert's death goes against what authorities had originally said: she died due to an accident.

Serial killer in our midst?

There is little to nothing known about whoever may have committed the murders.

There have also been discrepancies over how many suspects may be involved. In December 2011, Dormer, who died in April 2019, and then-Suffolk County District Attorney Thomas Spota engaged in a heated debate over the number at a legislative session, according to Newsday.

Dormer continued to say he believed there was only one killer involved, while Spota, who was convicted late last year in a police-beating cover-up, "openly criticized him," Newsday reported, and stood by his theory that at least three were involved.

Adding to the confusion was Dormer's attempt to assure the public in 2011. "I don't want people to think that we have a Jack the Ripper running around Suffolk County with blood dripping from a knife," Dormer said a the time. "This is an anomaly."

In the Jan. 16 press conference, Hart skirted around the issue, saying "It's important as a team we keep our mind open to all avenues and don't marry ourselves to one theory of the investigation. We go where the facts lead us. We do not speculate."

But in presenting the new piece of evidence, she did refer to only one suspect" who handled it.

Brad Garrett, an ABC News contributor and former FBI agent who has worked on dozens of cold cases and has been following this case for years, said that based on details of the killings, he believes whoever committed these crimes has a connection to Gilgo Beach.

"He knew that Gilgo Beach was there. He knew it was remote. Did he grow up there? Does he live there?" Garrett said.

Garrett also believes there is a single killer and that person is a male because of calls reportedly made to at least one of the victim's families by the suspect.

Pictures of women, whose bodies were identified among 10 bodies found near Gilgo Beach since December 2010, are seen in this Suffolk County Police handout image released to Reuters on September 20, 2011.

The killer is said to have used Barthelemy's cellphone to call her sister and make derogatory statements about Barthelemy, according to reports at the time. The person who made the call had a male voice.

Yet even with the characteristics Garrett laid out, he said "it doesn't really help you get any closer to him."

Other law enforcement officials familiar with the case have in the past speculated that the possible serial killer may have been an ex-cop or other law enforcement officer, according to a 2011 ABC News story.

The officials said it was a possibility because the suspect may have understood investigators' procedures and known how to hinder authorities' efforts.

New evidence

The new evidence, presented by Suffolk police in January, was a photo of a black leather belt embossed with the letters "WH" or "HM," depending on how it's held.

The belt had been collected at an initial stage of the investigation, though Hart would not say exactly where it was found.

Hart said at the press conference she believed the suspect in the murders "handled" the belt, but would not elaborate.

The locations where eight of 10 bodies were found near Gilgo Beach since December 2010 are seen in this Suffolk County Police handout image released to Reuters, Sept. 20, 2011.

When asked why she was releasing the image now after having had it for all these years, Hart appeared to dodged the question, speaking about technology and saying "Now is the time to release this information," without providing details.

A new website has also been created, gilgonews.com, to give the public an outlet to easily leave tips.

"There has been a tremendous amount of effort put into solving this case and I can tell you that everyone involved is motivated by one goal: to deliver justice to these victims and to give them some sense of peace and some sense of closure," she said at the press conference, which was held at Suffolk Police Headquarters in Yaphank, New York.

In the time since the new evidence was presented, authorities have not released any new information on the case.

Read more:

What we know and don't about Long Islands suspected serial killer case - ABC News