The victim, 29-year-old Kareem El, was shot in the head and killed back on April 8th as he drove in the eastbound lanes near the Montgomery Drive exit.
A passenger in the vehicle managed to bring the car to a stop.
Pennsylvania State Police investigators say one of the suspects, James Alston, 29, of Philadelphia, was arrested back on May 18th for a separate shooting.
As part of that investigation, police say they recovered a 9mm handgun, which was registered to 25-year-old Brent Coleman of Philadelphia.
That gun was sent to a ballistics laboratory, and it was learned that the same weapon was used to kill Kareem El.
As the investigation continued, police say they learned Coleman was the driver of suspect vehicle in El's death, and Alston was the passenger and shooter.
Coleman was arrested on January 8th.
Police say El was killed over a stolen phone.
Both men have been charged with 1st and 3rd degree murder and are being held without bail.