Jacob Lamar Crooks faced a charge of murder with a special circumstances allegation of shooting out of a vehicle, making him eligible for life without parole.
John Walton Jr. was charged with bludgeoning 30-year-old Alexis Parson and 15-year-old Malik El-Ameen, but prosecutors have added a third charge, alleging Parson was pregnant at the time.
The case became a focal point for the Antioch police scandal involving racist and homophobic texts along allegations that officers committed civil rights violations and other crimes.