CINCINNATI -- A white police officer who fatally shot an unarmed black motorist during a Cincinnati traffic stop won't face a third trial, a prosecutor announced Tuesday.

Hamilton County Prosecutor Joe Deters said he was dropping the case against 27-year-old Ray Tensing. Two previous juries couldn't reach a unanimous agreement on murder and voluntary manslaughter charges against the former University of Cincinnati officer.

"I don't like it. We believe we cannot be successful at trial," Deters said.

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Tensing shot Sam DuBose, 43, in the head after pulling him over for a missing front license plate on July 19, 2015. The officer, since fired, testified he feared he was going to be killed.

The shooting is among those across the nation that have raised attention to how police deal with blacks. DuBose's family and civil rights groups called for a third trial of Tensing. There have been several demonstrations and protests urging a third trial, and petition drives both for and against the idea.

Deters said DuBose's family are very upset about his decision.

"I feel badly," he said. "I've got to do what I think is right."

Ghiz declared a mistrial June 23 after the jury reported it was deadlocked after more than 30 hours of deliberations over five days. His second jury had nine whites and three blacks. The first had 10 whites and two blacks. They deliberated some 25 hours over four days in November before a mistrial was declared.

The second jury said it was almost evenly split. Prosecutors said the first jury had a solid majority in favor of convicting Tensing for voluntary manslaughter, while defense attorney Stewart Mathews said majorities of the second jury favored acquittal on both charges.

Deters said the case had been referred to federal prosecutors for them to determine if DuBose's civil rights had been violated, something DuBose's family had previously urged.

"I'm hopeful that the U.S. attorney's office will see fit to proceed in this matter," Deters added.

Sam DuBose WKRC

A spokeswoman for Benjamin Glassman, U.S. attorney for southern Ohio, recently said he was aware of the Tensing matter, but he declined to comment on whether federal authorities should get involved.

Tensing testified in his own defense at both trials and said he feared he could be dragged or run over as DuBose tried to drive away.

"I meant to stop the threat," he told jurors in his second trial. "I didn't shoot to kill him. I didn't shoot to wound him. I shot to stop his actions."

An expert hired by prosecutors said his frame-by-frame analysis of the former officer's body camera video showed Tensing was not being dragged by the car.

To convict Tensing of murder, jurors had to find he purposely killed DuBose. The charge carries a possible sentence of 15 years to life in prison.

The voluntary manslaughter charge means killing during sudden passion or a fit of rage. That carries a possible sentence of three to 11 years.

Mathews has a motion pending asking Hamilton County Judge Leslie Ghiz to acquit Tensing after the two mistrials. She has scheduled a July 24 meeting on the case.

DuBose had significant amounts of marijuana and cash on him, and Mathews contended he was desperate to get away from police because he knew he would be headed to jail.

Tensing had about three years of suburban police experience before joining the University of Cincinnati police in 2014. He had no record of using deadly force.

The university fired Tensing after his indictment. It restructured its public safety department and made other policing reforms. The university reached a $5.3 million settlement with DuBose's family, including free undergraduate tuition for DuBose's 13 children.

