OAK BEACH, N.Y. - After a yearlong search, police on Long Island announced Tuesday that they believed they had discovered the remains of a New Jersey prostitute whose disappearance sparked an investigation into a possible serial-killing spree.

With about a half-dozen news helicopters whirring overhead, Suffolk County Police Commissioner Richard Dormer said searchers found the bones around 9:15 a.m. in a dense thicket about a half-mile from where Shannan Gilbert, 24, disappeared after meeting a client for an early-morning sexual encounter.

Dormer said the medical examiner's office would confirm whether the remains were Gilbert's, but the commissioner left little doubt that officers had found their intended target.

"It's certainly a sad day for the Gilbert family," he said. "And our condolences to that family on the death of their daughter."

The remains were found by homicide detectives about a quarter-mile from where authorities last week found Gilbert's pants, shoes, pocketbook with ID, and other personal items. On Tuesday, they were searching on an aluminum amphibious vehicle equipped with pontoons when they came upon the remains.

Police were searching for the Jersey City woman last December when they discovered the first of what would become 10 homicide victims. The remains were strewn along several miles of thicket and bramble along a parkway leading to Jones Beach. The body believed to be Gilbert's was several miles east of where the others were located on the remote barrier island south of Long Island.

Mari Gilbert, Shannan's mother, said in an interview with Long Island Newsday that she was not convinced the body was her daughter's.

"I have no reaction until I get a positive ID from the medical examiner," she told the newspaper from her home in Upstate New York. "I just hope it is not" her daughter, she said.

While police believe a serial killer is responsible for the deaths of the 10, Dormer reiterated Tuesday that police think Gilbert likely drowned accidentally after fleeing the client's home for an unknown reason.

Dormer said the location of the skeleton suggested that Gilbert might have been trying to run through the wetlands to a causeway because it was illuminated by streetlights.

She was last seen shortly after 5 a.m. May 1, 2010. Dormer suggested that she had become hopelessly entangled in the brush, which he called a "tough, desolate, tangled mess."

"The terrain would have made it impossible" for her to get through to the road, Dormer said. "Our people who were in there over the last few days had to cut through that brush and bramble area before she was located."

Relatives of some of the other people whose bodies were found along a nearby beach highway planned to hold a vigil Tuesday to mark the anniversary of when their loved ones' remains were discovered. Melissa Cann, whose sister Maureen Brainerd-Barnes was among the first four victims found, and Lorraine Ela, the mother of victim Megan Waterman, were standing nearby when Dormer made his announcement.

Cann burst into tears and hugged Ela as cameras chronicled their grief.

Authorities at first believed several people could be involved, but Dormer said recently that detectives now suspected that one killer was likely responsible for all 10 deaths because the victims all had some connection to the sex trade.

The victims included eight women, a man, and a toddler. Police believe the women were prostitutes and suspect the man also was involved in the sex trade because he was found wearing women's clothing. The toddler is believed to be the child of one of the prostitutes. Only five of the 10 victims have been identified, and police have not commented on possible suspects.

Cann, of New London, Conn., and Ela, of Portland, Maine, said supporters would release balloons and light candles later outside at Oak Beach, a gated community near where the discoveries took place.

"We think it's important that we do as much as possible to keep the public aware of this case," Cann said. "There could be a clue out there."

Ela said Monday that she took a 14-hour bus trip from Maine to Long Island to attend the vigil. The families are holding a fund-raiser later Tuesday at a Wantagh nightclub to help defray their travel expenses.

Before the commissioner left, Cann spoke with Dormer and thanked him for the police effort in the investigation. Dormer assured her that while the case involving Gilbert appeared to be coming to a conclusion, the homicide task force investigating the possible serial killer would continue its work.