A former Dallas police officer was indicted on a murder charge on Friday for shooting an unarmed, 26-year-old African-American accountant who was watching TV in his apartment, a home that the officer says she mistook as her own.

A Dallas County grand jury charged Amber R. Guyger, 30, over the Sept. 6 killing of Botham Jean in his apartment, which was one floor above hers. If convicted, Ms. Guyger could receive five years to life in prison.

[Update: Amber Guyger testifies in her murder trial: “I shot an innocent man.”]

Ms. Guyger, a white officer who was returning from her shift but dressed in uniform at the time, said that she mistook Mr. Jean’s apartment for her own, that his door was slightly ajar and that it opened when she tried to unlock it. She thought he was a burglar, she said.

Lawyers for Mr. Jean’s family have said that the door was closed, and that neighbors heard someone banging on the door, demanding to be let in, before the gun was fired. Ms. Guyger fired her service weapon twice, striking Mr. Jean once in the torso, according to court documents. Mr. Jean, who worked at PricewaterhouseCoopers, died at a hospital.