WEST ISLIP - Suffolk police are searching for the driver who mowed down a man in West Islip last night and apparently left him in the road to die.Police say Jason Nelson, 26, of Brightwaters, was found on Sandra Avenue just before midnight. Nelson's father, Ronald Nelson, says his son had been living with his longtime girlfriend in West Islip. He had gone out to get a pack of cigarettes when he was struck. Ronald Nelson says his son's girlfriend found him lying in the road. He was still breathing when she found him, but died at the scene, the father says.Jason Nelson had worked in construction in Manhattan, including at Ground Zero, according to his family.Detectives are urging anyone with information to call Crime Stoppers at 1-800-220-TIPS.