Four other sets of remains have been found in the same area since 2000, including two belonging to Gilgo Beach victims.
"At this time we cannot say if the remains are connected to any other cases," Suffolk County Deputy Insp. Kevin Fallon said at a news conference Saturday. "We cannot yet determine the age or the gender of the remains."
Fallon said detectives would review the remains, which were found Friday and later taken to the Suffolk County medical examiner's office, before deciding whether police need to return to the area to search for more evidence.
A man and his dog found the bones on woodland that's part of the Upton Ecological and Research Reserve, a protected pine barrens overseen by Brookhaven National Laboratory.
Matt Samuel, 30, of Manorville, made the discovery about 6:30 p.m. Friday. He said he was heading home after hunting deer when he discovered the body, which looked like it had once been wrapped in a bedsheet and a plastic bag.
"I have probably walked by it 100 times," said Samuel, who described what he saw as a complete skeleton that was half above ground and half buried.
The remains were found 300 feet from North Street on the 530-acre tract, which is north of the Long Island Expressway, police said.
Police brought in a forensic anthropologist from the chief medical examiner's office in New York City to assist in removing the remains.
The skeletal remains are believed to have been left at the scene at least five years ago based on the growth of vegetation in the area, police said.
The Manorville location is four miles from where the partial remains of Gilgo Beach slaying victim Jessica Taylor, 20, of New York City, were found more than eight years ago.
Taylor's nude torso was found in July 2003 by a woman walking her dog near Halsey Manor Road and the Long Island Expressway, police said.
Other parts of Taylor's body were found in the dense brush off Ocean Parkway in the Gilgo Beach area on March 29, 2011.
Remains of another woman -- known to authorities only as Jane Doe No. 6 -- were found near a Manorville sump discharge basin on Nov. 19, 2000. Those remains were found in a heavily wooded area about a half-mile west of Halsey Manor Road and north of the Long Island Expressway, police said.
Police found other parts of Jane Doe No. 6's body off Ocean Parkway on April 4, 2011.
Taylor, Jane Doe No. 6 and eight other sets of remains were found between December 2010 and April 2011 in the Gilgo Beach area. Police believe that all 10 had been killed.
Friday's discovery was near where two unidentified men were found in 2000 and 2003, police said. Those bodies have no connection to the Gilgo Beach cases, police said.