5 Things to Know About the Long Island Serial Killer — and Clues Revealed by the Victims

It’s been close to six years since police discovered more than 10 bodies around New York’s Gilgo Beach area on Long Island — a grisly case that began when Shannan Gilbert, a 24-year-old escort, disappeared in May 2010 after meeting a client through Craigslist.

To this day, the cases of Shannan and the other victims (almost all women) remain unsolved, and the mysteries surrounding their deaths endure.

Here are five things you need to know about why.

1. Shannan told a 911 Dispatcher, ‘They’re Trying to Kill Me!’

On the night of her disappearance, Shannan frantically called 911 after she ran out of the home of her client and vanished without a trace somewhere in the gated community of Oak Beach.

Shannan’s family, who are adamant that she was a victim of foul play, have long maintained that the 23-minute tape of her emergency call could shed light on what really happened that fateful May 2010 night.

But law enforcement, who insist Shannan likely died of natural causes in the marshy swampland around the beach, has refused to release it.

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The battle over the tape is now playing out in a New York courtroom. “We will be able to actually identify not only the people that were there but to hear the actual words,” Mari Gilbert told PEOPLE before, in a tragic turn, she was fatally stabbed in July.

“I think we will get them eventually.”

2. The First Four Victims Found Were Wrapped in Burlap

In December 2010, an officer and his dog out searching for Shannan on Gilgo Beach stumbled upon the body of a woman wrapped in burlap. Over the next several days, the officer discovered the remains of three other young women dumped in the marsh near Oak Beach.

The bodies, each wrapped in burlap, were found within about 500 feet of each other. Authorities believe each woman interacted with her killer via online ads and cell phones.

Maureen Brainard-Barnes, 25, disappeared first — in July 2007, from New York City — after checking out from a Super 8 motel. “I was the last person to see her alive,” her friend Sara Karnes tells PEOPLE.

Melissa Barthelemy vanished next, in 2009. Barthelemy’s mother, Lynn, tells PEOPLE that she had no idea her 24-year-old daughter worked as an escort. “When she first went to New York City, she said she was working at a hair salon and then she said it got slow so she was bartending at some nightclub, but she was still working at the hair salon. That is about all I knew.”

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Then, on June 5, 2010, Megan Waterman disappeared from a Holiday Inn Express she was sharing with her boyfriend Akeem Cruz in Hauppauge, New York, after she placed an ad on Craigslist. A video camera showed the 22-year-old Maine escort leaving the hotel around 1:30 a.m.

The last of the first four girls to disappear was 27-year-old Amber Lynn Costello on September 2, 2010. The twice-divorced Costello had negotiated a $1,500 date with her alleged killer before she walked out of her Long Island home. “She talked to the guy a couple of times, and she made a bad judgment call and it bit her in the a– in the end,” Costello’s sister, Kim Overstreet, tells PEOPLE. “It was somebody she didn’t know.”

3. It’s Not Clear How Many Victims There Are

In March 2011, two months after police identified the first set of four remains, the remains of six more bodies were unearthed along the beach.

“I believe that crime scene search was probably one of the largest crime scene searches we’ve ever had in the history of the police department,” Suffolk County Police Chief Stuart Cameron tells PEOPLE.

Four of the remains found were women, one was a female toddler and one was an Asian male wearing women’s clothing. Two sets of the remains were later linked to the dismembered torsos of two women discovered in Manorville, about 40 miles away. One of them was identified as 20-year-old prostitute Jessica Taylor whose torso was found in Manorville in 2003. The rest of the remains have never been identified.

Since then, police have looked at five more bodies discovered around the Gilgo Beach area, raising questions about whether their deaths are related. One of the bodies belonged to 31-year-old Natasha Jugo, whose body washed up on Gilgo Beach in 2013.

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“We can’t say beyond a shadow of a doubt all these murders are connected,” says serial-killer profiler and expert John Kelly. “But serial killers can change their [methods]. A sadistic killer would be about convenience.”

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4. The FBI Is Also Investigating the Case

In December 2015, Suffolk County Police Commissioner Tim Sini announced that the FBI would join the hunt for the killer or killers — and by February 2016, he launched a Gilgo Beach task force, assigning two full-time detectives to focus only on the case and work alongside the FBI.

“We are doing everything in our power now to get this case solved,” Sini tells PEOPLE. “Wherever the evidence leads is where we are going to go. We are trying to take a really fresh look. I am very cautiously optimist. I do think this is a solvable case.”

But some victim’s family members wonder if it is just too little too late.

“The FBI should have been involved from the beginning,” Overstreet says.

5. The Long Island Serial Killer, Whoever They Are, Is Still At Large

Police have made no arrests in the Gilgo Beach deaths and have not publicly revealed if they have any suspects in the case. But plenty of theories abound.

Over the years, there has been speculation that the killer is a drifter, a fisherman, a seasonal worker or a businessman who commutes from Long Island to New York City because the burlap victims disappeared in the summer months. There were also rumors of a secret sex ring made up of wealthy men who allegedly hired escorts and prostitutes for sex parties.

More recently, the suicide of a prominent local businessman the day after Shannan’s body was discovered has fueled rumors that he was involved in the slayings.

“There have been a lot of rumors, a lot of suspects rumored,” Chief Cameron tells PEOPLE. “I would almost equate some of it to the clown sightings we’re having now. There’s no sense to a lot of this stuff.”