The crash just after 1 a.m. forced closure of all eastbound lanes for more than an hour as police and firefighters attended to the driver and the overturned sport utility vehicle, which landed on its roof.
Nassau police had not yet identified the driver and released few details about the crash. The cause was being investigated.
Witness John Fedder, 52, of Merrick, was taking a break from his job at a car dealership on the LIE service road when he said he saw a dark-colored SUV driving east in the left lane swerve into the center lane around a car.
"The next thing you know it's rolling end-over-end, like three times," he said.
Police placed a white sheet over the vehicle, which rested in the eastbound expressway's center lane, west of Round Swamp Road. An officer at the scene said the driver was thrown from the vehicle and killed, according to another witness.