– A former Dallas police officer who shot her unarmed black neighbor in his own apartment was found guilty of murder Tuesday in a high-profile case that dealt with issues of race, policing and mistaken identity.

The former officer, Amber R. Guyger, who is white, was charged in the death of her 26-year-old neighbor, Botham Shem Jean, after she said she accidentally went to the wrong floor of their apartment complex, entered the unit directly above hers and fatally shot him last year. Guyger claimed she thought she was entering her own apartment and was acting in self-defense against an intruder.

But on the second day of deliberations, the jury rejected that argument and returned a rare murder conviction against a police officer who, in this case, was off-duty but in uniform.

Family members of Jean, an accountant who was home watching TV and eating ice cream on the night of the shooting, had braced themselves for the possibility that the jury would return with a lesser charge of manslaughter — or none at all. After the judge read the verdict in the courtroom, Jean's sister sobbed. His mother raised her fists in the air and looked upward. "God is good," she said.

Guyger, 31, faces a prison sentence of between 5 and 99 years.

The shooting in September 2018 ignited protests and calls for justice, with demonstrations outside police headquarters and inside City Hall. Activists complained that Guyger was not immediately arrested at the scene but charged with manslaughter several days later. After weeks of community tensions and accusations of preferential treatment for the police, a grand jury came back with the charge of murder.

At a time when other police officers have often been cleared of wrongdoing in the deaths of unarmed black men, the outcome in this case was being closely followed among activists who have called for more police accountability. When the courtroom doors opened Tuesday, chants erupted in the hallway, as supporters repeated the verdict aloud and shouted an affirmation they had been waiting to hear: "Black lives matter."

At a news conference, lawyers for Jean's family recited the names of other black people who have been killed in confrontations that drew public criticism in recent years — Trayvon Martin, Michael Brown, Tamir Rice — and said they hoped the latest verdict would be a turning point for racial justice and police reform. "For so many unarmed black and brown human beings across America, this verdict today is for them," said Benjamin Crump, a civil rights lawyer for the family.

"People in Dallas County worked hard to create an environment where justice is possible," said S. Lee Merritt, another civil rights lawyer who represents Jean's family.