The Dallas Police Department has fired officer Amber Guyger.
The 30-year-old had been on administrative leave after fatally shooting her neighbor Botham (boe-tham) Jean earlier in September.
Guyger claimed she mistakenly entered Jean's apartment thinking it was her own and shot him because she thought he was an intruder.
The Dallas police chief says the department dismissed Guyger for her actions on that night and for engaging in quote "adverse conduct" when she was arrested.
Police did not elaborate on what the adverse conduct was.
The decision to fire Guyger, who faces a manslaughter charge, comes after an internal review.
Police say she can appeal the decision.
Jean's shooting death sparked protests in Dallas, with many calling for the officer to be fired and charged with murder.
It's also become a heated election issue in the U.S. Senate race between incumbent Ted Cruz and his opponent, democrat Beto (bay-do) O'Rourke.
SOUNDBITE: BETO O'ROURKE, SAYING: "With the tragic shooting death of Botham Jean you have another unarmed black man killed in this country by aw enforcement.
The case is now before a grand jury, which could decide to uphold the manslaughter charge or elevate the charge to murder.