CINCINNATI — The encounters with the police officers turned deadly within seconds. Each time, a black man was fatally shot, and each time, it was captured on video. And three times in the span of a week, the officers’ trials have ended without a conviction.

On Friday, it was jurors here who were hopelessly deadlocked in the retrial of Raymond M. Tensing, the former University of Cincinnati police officer who faced charges of murder and voluntary manslaughter for fatally shooting Samuel DuBose, an unarmed motorist, in 2015. Mr. Tensing’s first trial, held last fall, also ended with a hung jury.

“We are almost evenly split regarding our final votes,” read the note passed from the jury to Judge Leslie Ghiz, who declared a mistrial as rain lashed against the windows of her chilly downtown courtroom. Mr. Tensing dropped his head into his hand and squeezed his eyes, while one man seated with Mr. DuBose’s family hung his head and looked out at the rain.

As she walked out of the courtroom, Terina DuBose-Allen, a sister of Mr. DuBose’s, spoke quietly: “I think it’s horrible.”