Ms. Edwards also acknowledged that before the start of the murder trial she was pessimistic about the prosecution’s chances, after watching police shooting cases like those involving Michael Brown, Tamir Rice, Philando Castille, Clinton Allen, Alton Sterling, Terence Crutcher and others.

“If I have to be honest, I wasn’t looking for a conviction because quite naturally you’ve seen across the nation where this has happened so many times and no one is held accountable,” she said. “So I figured that it would be another one of these occasions where a police officer is not held accountable for his actions.”

Ms. Edwards, 35, said she thought of the many other families of police shooting victims.

“I’m them,” she said. “I was in their shoes just two weeks ago, sitting here wondering: Was I going to get a conviction?”

“So, of course, I totally feel the way they feel,” she added. “The only difference is that I see results from his death. My heart is with them because I know it still hurts and I know it hurts as a mother for them: To see a conviction for another black life lost and their child still didn’t get justice.”

One exception is Judy Scott, the mother of Walter Scott, an unarmed black motorist who was killed in North Charleston, S.C., in 2015 after a traffic stop. That case ended in a mistrial, but the officer, Michael T. Slager, pleaded guilty to a civil rights violation and was sentenced to 20 years in prison.

Next week in Chicago, Officer Jason Van Dyke, who shot the 17-year-old Laquan McDonald 16 times in October 2014, is scheduled to go on trial. He is the first Chicago police officer in decades charged with murder for a fatal on-duty shooting.

In this week’s case in Dallas, 12 jurors, two of whom were black women, decided unanimously to convict. The county is about one-quarter black.