Suffolk County police announced Thursday that they have enlisted the aid of the FBI to help them solve a series of murders that has left them stumped for the past five years.

Authorities have uncovered ten sets of human bodies between Gilgo and Oak beaches in Suffolk County, about 40 miles east of New York City, since the investigation began in December 2010, according to PIX 11.

The case started as a normal missing persons case when authorities were searching for Shannan Gilbert, a New Jersey prostitute who went missing in May 2010. However, they soon started to investigate it as a serial murder in December of that year when police uncovered the remains of several more women clustered 500 feet away. Glibert's body wasn't found until more than a year later.

Ten bodies in total - eight women, one man and a toddler girl - were discovered, reported ABC News. Some of the bodies were found in burlap sacks, and five of the victims were identified as prostitutes who went missing after advertising for clients online.

No suspects have been identified, and police have speculated that a single person might be involved in all the murders, adding that the victims were killed elsewhere and were then transported to Gilgo Beach.

In light of this, Suffolk County authorities asked the FBI to play a more prominent role in the investigation, according to Reuters.

"Rest assured this case remains active," Suffolk County Deputy Police Commissioner Tim Sini said at a news conference. "We know we are doing everything we can to solve these murders."