At around 1:45 a.m., Penton was securing traffic with the emergency lights from his squad car on after an accident in the northbound lanes of North Central Expressway at Walnut Hill Lane.
Police said Mabry was driving a Kia Forte at a high speed and hit the back of Penton's squad car, which pushed the car into Penton.
Penton was taken to Baylor University Medical Center, where he died.
Police said Mabry was found to be intoxicated. He faces a charge of intoxication manslaughter on a police officer and intoxication assault in connection with the passenger who was in his vehicle.