Suffolk police top brass assured families of victims of the Gilgo Beach killings Thursday that, even after five years, the investigation remains active, and the department has asked the FBI to assist in the probe.

“As we approach the [five-year] anniversary, on behalf of the Suffolk Police Department, I want to convey to the loved ones and the families of all the victims that we are dedicated to do everything we can to solve this case,” Deputy Police Commissioner Tim Sini said. “Rest assured, this case remains active.”

“Anniversaries create opportunities,” Sini said. “We’re here today because we think it’s important to let the public know we are doing everything we can to solve these murders.”

Sini, a former federal prosecutor appointed last month to replace retiring Police Commissioner Edward Webber, said that in his experience, cooperating with federal authorities can speed up an investigation.

He declined to comment on specific details of the case or disclose any recent developments.

The discovery of bodies along Ocean Parkway took place during the search for Shannan Gilbert, a Jersey City, New Jersey, woman who was reported missing in May 2010.

advertisement | advertise on newsday

Suffolk Police Chief of Department Stuart Cameron, who ran the search operations on the case as commander of the Special Patrol Bureau, called the search for Gilbert, “the largest crime scene search in the department’s history.”

The FBI has assisted Suffolk police in the past, but at the department’s request, federal investigators “will take a more active and prominent role,” Sini said at a news conference Thursday at police headquarters in Yaphank.

Federal agents were not present during the news conference, but FBI spokeswoman Kelly Langmesser said later the agency has agreed to assist.

On Dec. 11, 2010, a Suffolk police officer and K-9 partner searching for Gilbert instead discovered the body of Melissa Barthelemy, 24, of the Bronx, in a thicket of bramble in Gilgo Beach.

Hers was the first of 10 bodies found in the area. Five of the 10 victims have yet to be identified.

The discovery of the remains, over a period from December 2010 to April 2011, would become one of Long Island’s most baffling unsolved mysteries. The high-profile case gained worldwide attention, inspired plays and a movie and launched conspiracy websites, several documentaries and a book.

The case has sparked conflicting theories even among law enforcement officials on whether police are looking for one or more killers, based on the various conditions of the remains and the identities of the victims.

Some of the finds were body parts; one was an Asian male dressed as a woman, and one was a toddler.

But the first four bodies were those of women in their 20s who worked as prostitutes and were found within a quarter of a mile from each other. The victims had been reported missing between 2007 and September 2010.

Experts say investigators face difficult challenges in cracking the case.

advertisement | advertise on newsday

“They’ve had little to work on from the very beginning,” said Joseph Giacalone, a former NYPD commanding officer of the Bronx cold case squad and an expert on criminal investigations. He teaches at John Jay College of Criminal Justice.

Investigators have been hampered by the fact that all the bodies were found in a state of advanced decomposition and because they had not been buried, were exposed to months or years of a harsh waterfront environment.

Shortly after the first four bodies were found, FBI profilers from the Behavioral Analysis Unit of the bureau’s National Center for the Analysis of Violent Crime in Quantico, Virginia, helped Suffolk police develop a possible profile of the killer.

But at the University of Maryland at College Park, forensic science professor Thomas Mauriello cautioned against counting too much on theories of profilers.

“Trying to guess what they might be doing and what they might look like and what their age might be or whether they are familiar with the area or not familiar with the area, in my opinion, is not helpful to the public, but only helpful to the people committing the crime,” he said.

advertisement | advertise on newsday

Mauriello said the advent of DNA analysis now makes it easier to catch a serial killer.

“I look at a serial murder or a series of serial type murders as no different than any other case. There is evidence at the scene,” he said. “If anything, if the person is doing something over and over again, I mean developing a pattern, that helps the investigators because eventually they [the killers] mess up somewhere.”

In 2011, outgoing Suffolk Police Commissioner Richard Dormer announced that he believed all the killings were the work of one serial killer, prompting a public rebuttal from Suffolk District Attorney Thomas Spota.

Spota had announced months earlier that investigators believed the killings were the work of two or three suspects.

Authorities have agreed Gilbert’s death is not related to the others. Gilbert, 24, was reported missing after she disappeared on May 1, 2010, in Oak Beach, where the sex worker had been summoned to a client’s home. Her body was found in December 2011 in a marshy area in Oak Beach.

John Ray, who represents the Gilbert family, said he had been trying to get the FBI involved since December 2011.

Ray said the family will be “delighted,” but added, “It remains to be seen what the police will do to cooperate with the FBI. New involvement gives me hope.”

Four of the Gilgo Beach victims were Barthelemy; Maureen Brainard-Barnes, 25, of Norwich, Connecticut; Megan Waterman, 22, of Scarborough, Maine; and Amber Lynn Costello, 27, of North Babylon.

Some of the rest of the unidentified remains have been tied to ones found in 1999 in Blue Point Beach and Manorville in 2000 and 2003.

Jessica Taylor, 20, of New York City, was the last person to be identified. In 2011, Taylor’s head, hands and forearm were found east of Gilgo Beach along Ocean Parkway. Her torso was found in 2003 in Manorville.

“You want to close a case like this,” said Giacalone. “This is 10 open homicides in Suffolk County.”

With Laura Blasey