The incident happened around 6:30 p.m. at the Marquis Apartments in the 200 block of West Dekalb Pike.
According to police, the 14-year-old girl fell from a window in her apartment unit in building C of the complex.
They say she was climbing out the window when she fell and landed on the roof of the apartment parking garage.
Investigators said the girl had been grounded, and was trying to climb down from her window with a makeshift rope composed of shoe laces and electrical cords tied to a heater.
She was taken to Mercy Suburban Hospital for treatment where she was later pronounced dead.
Police are treating this incident as an accident.