An elderly Mattituck man was pronounced dead at a local hospital after he was found unresponsive in a swimming pool Sunday, police said.
Family members found Joseph Sieczka, 79, in the pool on New Suffolk Avenue at 6:39 p.m.
They initiated CPR, which was continued by a responding police officer and members of the Mattituck Fire Department until he was transported to Peconic Bay Medical Center in Riverhead, where he was pronounced dead, police said.
Officials are performing an autopsy to determine the cause of death.
Police do not suspect foul play.
Sieczka was reportedly a good swimmer, police said. The family members came to the residence at about 6 p.m. and were there for about a half-hour before finding him in the pool, police said.