Law professor Dan Markel was reportedly talking on his cell phone and pulling into the driveway of his Florida home when he was ambushed and shot dead.
The killer was waiting for Markel, 41, outside his home in Tallahassee on July 18 and followed Markel into the garage, ABC News reported.
The attacker shot the popular professor in the side of the head through the window of his car in broad daylight.
Markel was alive when cops arrived, with the keys in the ignition of his car, before being pronounced dead at the hospital hours later, police said.
A police report said a neighbor heard a single gunshot and called 911.
The neighbor eported seeing a silver Toyota Prius drive away from the scene. Police later released a grainy surveillance image of that car.
Markel was apparently on the phone at the time of the shooting, and told the person on the phone that someone was in the driveway, ABC News reported.