It was a bitterly cold afternoon four years ago when a Suffolk County cop’s German shepherd sniffed out the skeletal corpse of Melissa Barthelemy, 24, a Bronx prostitute who had vanished a year and a half earlier.

The cop had been looking for a different woman, but the dog’s discovery of Barthelemy’s body in a crumbling burlap sack amid the thorny underbrush off Ocean Parkway in Gilgo Beach, Long Island, exposed something unexpected.

It was the sickening work of one of New York’s most prolific serial killers ever — with a body count of at least 10 victims and as many as 17.

Dubbed the Gilgo Beach Killer, he’s been stalking and slaughtering his prey for two decades, some believe, with a methodical efficiency that has detectives no closer to catching him today than they were on that frigid day of Dec. 11, 2010.

The search for the elusive predator has, in fact, stalled, according to a police source.

Detectives have not advanced the case in recent months and are in need of a tip from the public or lucky break, says the source, who has access to information about the probe.

“It’s been four years, and they’ve not got too much to show for it,” said the State Police officer, who is not involved in the investigation but is familiar with the work of those who are.

Suffolk County cops will say nothing. They’ve refused to speak with the media and won’t tell families of victims what they’re doing or if any progress has been made.

All they say is that when they find the killer, I’ll be the first to know. They’re lying. - Mother of victim

The department is “not commenting further at this time on the Gilgo investigation until or unless we have some additional information pertaining to the investigation that serves the investigation or the public by its release,” a spokesman said.

Being left in the dark has infuriated some of the families.

“All they say is that when they find the killer, I’ll be the first to know,” said Marie Ducharme, the mother of victim Maureen Brainard-Barnes. “They’re lying. They’re saying that just to keep me satisfied.”

Ducharme slammed police for how they’ve conducted their probe, which has been plagued by unfounded rumors, misinformation, public spats among officials and flip-flopping theories — with probers vacillating between there being one or two murderers. (It’s one, police say now.)

“If they had [done a good job], they would have found the killer already,” she said.

The Gilgo Girls

Within days of unearthing Barthelemy’s remains, police found the bodies of three more young call girls who booked appointments on Craigslist and went missing between 2007 and 2010: Brainard-Barnes, 25; Megan Waterman, 22; and Amber Lynn Costello, 27.

Each had been strangled elsewhere, wedged into burlap and dumped amid thick scrub just off the sand-swept causeway on the inlet side of Gilgo in the town of Babylon.

Six more bodies, or parts of bodies, were discovered over the next year in different areas of Suffolk and Nassau counties. Some victims had been hacked up, their limbs scattered across remote sections of Gilgo, Oak Beach and elsewhere.

Among them was a young Asian man dressed as a woman killed by a blow to the head and a female sex worker and her toddler child, who was found wrapped in a blanket. Both mother and daughter had on inexpensive jewelry. Officials displayed the girl’s earrings and necklace in the hope that someone might recognize the items.

They also put out artist sketches of the two unknown adults, which generated tips but failed to solve the mystery of their identities. Of the 10 bodies, just five have been identified — the original four plus Jessica Taylor, 20, a prostitute whose skull, hands and forearm were recovered in May 2011 near Gilgo. She’d been dead for many years; police recovered her torso in Manorville in 2003.

Seven more possible victims have since been considered.

They include “Peaches,” a black woman whose tattooed torso, featuring a heart-shaped peach on her left breast, turned up in a Rubbermaid container in 1997 in Hempstead Lake State Park; “Cherries,” another female with a tattoo — of two cherries, also on her left breast — who’d been stabbed and washed up on a beach in Mamaronek in 2007; and two Long Island prostitutes, one identified as Tanya Rush, 39, a Brooklyn mom whose hacked-up body was found in 2008 in a small suitcase off the Southern State Parkway in Bellmore.

Cops are studying two more bodies, each found in 2013: the remains of an Asian woman in Lattingtown, near Oyster Bay, who had on a necklace with a 22-karat gold pendant of a pig, and Natasha Jugo, 31, a Yugoslavian-American woman from Queens whose body washed up onto Gilgo Beach on June 24, 2013.

The group also includes Shannan Gilbert, the call girl whose disappearance in May 2010 prompted the search that led police to Barthelemy.

Gilbert had fled the home of a wealthy client in Oak Beach, Joseph Brewer, in what appeared to be a drug-induced panic, then made a cellphone call in which she claimed, “They’re trying to kill me.”

At one point she pleaded with a neighbor for assistance. Police say she ran off again and died accidentally, possibly by drowning in a marsh, and was not a victim of foul play.

Her badly decomposed body was found in December 2011 not far from where she was last seen.

Her mother, Mari Gilbert, insists Shannan was killed — and sued a doctor, Peter Hackett, who saw her that night and allegedly did nothing to help. The suit says Hackett, whose home Gilbert ran to on the night of her death, gave her drugs and sent her off. Much of her complaint has been tossed out on a technicality involving statutes of limitations.

Mari also sued the Suffolk County PD and enlisted the assistance of renowned medical examiner Michael Baden to review her daughter’s autopsy and have her case reclassified as a homicide. Baden is at work on the matter now.

Chilling phone calls



Investigators believe the killer is probably an educated white man in his 30s or 40s, married or with a girlfriend, who knows the South Shore of Long Island well — living there now or previously.

They surmise he is comfortable financially, owns a car or truck needed to transport victims, and could have a job in which he has ready access to burlap sacks — such as with a garden center or nursery. They believe he is tech-savvy and familiar with police methods, possibly working in law-enforcement or having friends who do.

Police are fairly certain that he buried some bodies or stored them before dumping them, and it’s possible he only visits the area seasonally since the first four women who were found disappeared between Memorial Day and Labor Day. Could he be abducting his victims during the summer, then disposing of their corpses in winter, when few people are around? The first four victims vanished between three years and three months prior to their remains being discovered. But it’s unclear if the killer put them there all at once or over time.

He is, in short, blending in, hiding behind an Average Joe facade while plotting his next murder, police believe. The most recent known victim is Costello, 27, who lived 10 miles north of Gilgo in North Babylon and was last seen on Sept. 2, 2010, when she went to meet a john who had offered her $1,500.

The killer possesses an especially sadistic streak: he used Melissa Barthelemy’s cellphone to call her sibling Amanda’s cell within days of Melissa’s disappearance on July 10, 2009.

“Is this Melissa’s little sister?” the killer asked, according to the girls’ mom.

“Yes,” replied the 16-year-old girl.

“Do you know what your sister is doing?” he said. “She’s a whore.”

That was something Melissa had not revealed. “No one else knew,” said their mother, Lynn Barthelemy, noting that the killer’s information had to have been extracted from Melissa.

He called the terrified teen half a dozen more times — each time using Melissa’s cellphone, with police listening in and trying to trace the call. Her parents wondered if the killer had gotten a glimpse of Amanda during the girl’s two visits to see Melissa in New York.

NYPD cops did their best, pinpointing the calls to crowded areas of Midtown Manhattan but couldn’t find him. They also believe the killer turned on the phone once in Massapequa — a town just 10 miles from Gilgo.

The suspects



The Gilgo Beach Killer is the fourth fiend to slay multiple prostitutes on Long Island since 1989, so cops have been down this road before — and had no shortage of potential suspects.

One person of interest was Lucius Crawford, a 60-year-old ex-con from Westchester County who was wanted for stabbing to death two women in the 1990s — one in Yonkers; one in The Bronx — and was in jail for a stabbing from 1995 to 2008. When cops found him in 2012, he was at home with a third dead woman in his bed. But police crossed him off their list, citing a lack of evidence.

As they did with Joel Rifkin and Robert Shulman, who went on killing sprees 25 years ago and were in prison at the time of the Gilgo murders. Collectively, the lone wolves were convicted of killing 14 woman, though Rifkin, who murdered nine, was suspected in 17 additional deaths. Both eluded capture for five years and are now serving life sentences.

They also eliminated John Bittrolff, 48, a carpenter from Manorville, LI, who in July was charged with strangling two prostitutes 20 years ago and dumping their naked bodies in the woods near the Long Island Expressway. He’s pleaded not guilty in that case. Cops say he’s suspected in a third murder but not in the Gilgo case, though they have not revealed the exculpatory evidence.

Investigators also looked at a pair of NYPD cops who got into trouble for frequenting prostitutes, and James Bissett, a wealthy Long Island businessman who owned a nursery and killed himself in 2011. Rumors swirled about the motives for his suicide, but investigators say he’s been crossed off the list of suspects.

Cops also cleared Brewer, the client who hired Shannan Gilbert on the night she died, and Hackett, the neighbor who Mari Gilbert claims turned away her distraught daughter but not before drugging her.

Brewer admits he hired Gilbert, who was in his house for three hours, but claims the two never had sex and that she fled his home in a paranoid terror after taking a large quantity of drugs.

Hackett claims he gave Gilbert medicine to calm her down and tried to reach her family to get help but no one came and she ran off.

Brewer continues to live under a cloud. A self-published roman à clef, “Confessions of The Oak Beach Drifter,” by an author known only as W.W., casts suspicion on a character (named Damon Brooks in the novel) who bears a strong resemblance to Brewer. The Brooks character beats up a prostitute.

Slipping away



So who really is the Gilgo Beach Killer? And will the police ever catch him?

The best chance so far might well have come in Times Square, not Long Island, soon after Melissa Barthelemy vanished in 2009.

That’s when NYPD detectives, working with her mother, Lynn, triangulated one of the killer’s calls to the tourist mecca. They rushed in, dashing into porn shops and other locations, in a frantic bid to nail him.

But he never stayed on the phone for more than three minutes — and soon stopped calling.

The killer slipped away, a face in the crowd.