The shooting happened last Monday, October 19 on the southbound lanes of the highway near Exit 9 in Tinicum Township.
Around 5:30 p.m. police found the driver, 31-year-old Clifford Douby, inside a black Honda that had crashed into the rail on the southbound lanes of the highway.
Police said a bullet had pierced Douby's neck and he was found dead at the scene.
Police said the shooter was in an off-white or light-colored SUV, possibly a Mazda, with a temporary paper registration of an unknown state.
They believe the vehicle either continued south on I-95 or may have exited onto I-476 North.
Anyone with information is asked to contact the Pennsylvania State Police, Criminal Investigation Unit, Media Barracks at 484-840-1000 and ask to speak with a Criminal Investigator.