Marcellis Stinnette died in the shooting last week. His girlfriend Tafara Williams was injured.
The officer who shot Stinnette and Williams told investigators he opened fire on the car as it sped in reverse toward him.
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That officer has been fired due to what the police department called multiple policy violations.
Both Illinois State Police and the FBI are investigating the shooting. Lake County State's Attorney Michael Nerheim said he asked the U.S. Justice Department to review the circumstances surrounding the shooting.
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Williams' family said she was shot in the stomach and hand, and remains hospitalized. While Stinnette's family maintains that he died at the scene, police said he died at the hospital.
"Why did you shoot? I didn't do nothing wrong. I have a license. You didn't tell me I was under arrest. Why did you just flame up my car like that? Why did you shoot," Williams asked from her hospital bed.
"When I got there, she said, 'Mama, they just shot us for nothing,'" said Clifftina Johnson, mother of Williams. "My daughter said she put her hand up, and if she didn't put her hand up, she said, 'Mama, I would be dead.'"