A Ronkonkoma swimmer drowned in waters off Smith Point County Park in Shirley Monday afternoon, Suffolk County police said.
Beachgoers pulled an unconscious Kerry Agosto, 48, out of the water just before 12:15 p.m. and tried to resuscitate him, homicide Det. Lt. Kevin Beyrer said.
"He went into the water, he was swimming, he seemed to be fine," he said. "Then people noticed him floating, and he came up on the beach."
Agosto was taken to Brookhaven Memorial Hospital Medical Center in East Patchogue, where he was pronounced dead, police said.
His belongings and vehicle were found, and detectives believe he went to the beach by himself, Beyrer said.
Lifeguards were on duty but they were at the main part of the beach and Agosto was spotted some distance from the monitored areas, homicide investigators said.
Police said the investigation is continuing. It was not clear why he drowned and whether he had a medical episode.
A call to the park's office was not immediately returned.