Ten state police dogs trained to locate bodies were brought in to aid the search.
"There are no suspects at this time. It's just that we want to cover all of the areas that may be of interest," Suffolk County Police Commissioner Richard Dormer said a morning news briefing. "We want to make sure that we didn't miss anything."
The search is covering much of a narrow barrier island along Long Island's southern coast that is home to some of New York's most popular beaches.
The four bodies are still unidentified, but the investigation has focused on several missing prostitutes, including a New Jersey woman who disappeared in May after an incident at a home a few miles down the road from where the remains were discovered.
A resident of the small oceanside community of Oak Beach has told reporters and investigators he hired the woman, Shannon Gilbert, for a "date" in May.
Dormer confirmed that investigators removed an SUV from the man's home and had searched the house. He wouldn't comment on why they wished to examine the SUV.