Fox is being charged with murder and possession of a firearm during the commission of a crime, Jackson said.
On Oct. 18, a body was found in the trunk of a car in the north parking lot, which is free to commuters.
MARTA police did an initial investigation, opened the trunk and found the body of Christopher J. Dean, 33, of Lithia Springs.
Police are investigating both homicides and anyone with information about either case is asked to call MARTA police at 404-848-4911.