HEMPSTEAD - An X-ray specialist is accused of fatally hitting a man and his dog, then fleeing the scene.

Authorities say 42-year-old Robert Michels and his dog Sparky, a husky/lab mix, were out walking along Old Swamp Road in Old Bethpage at around midnight Thursday when they were fatally struck by a car.

Less than an hour after the accident, police say the driver, 37-year-old Matthew Johnstone, returned to the scene in his mangled pickup truck.

In court today, Johnstone's lawyer told a judge that he was returning from his shift as an X-ray specialist at Huntington Hospital when the accident happened. He says Johnstone realized he hit something, but it's still unclear why he didn't stop.

Prosecutors say Johnstone returned to the scene with his future father-in-law, who is a former NYPD detective.

Johnstone is charged with leaving the scene of an accident.