CINCINNATI (Reuters) - A former University of Cincinnati police officer on trial for the murder of an unarmed black motorist feared for his life as the traffic stop unfolded, his attorney said on Thursday.

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DuBose’s death fueled U.S. demonstrations against the use of lethal force by white officers against unarmed blacks and other minorities, an issue that renewed debate about racial bias by police.

Officer Ray Tensing, 27, shot once, hitting Samuel DuBose, 43, in the head, body-camera video showed, after stopping him for a missing front license plate on his car in July 2015. Tensing, who is white, is charged with murder and voluntary manslaughter in a retrial.

“Ray Tensing, as he made that traffic stop, he didn’t anticipate that Sam DuBose was going to drive off with Ray’s arm caught in that car,” Stew Mathews told the jury during opening statements at a county courthouse in Cincinnati.

“This all happened so quickly that instinctively Ray Tensing did the only thing he could do to save his own life,” Mathews added.

Tensing, who has pleaded not guilty and is free on a $1 million bond, was afraid he would be dragged and possibly killed as DuBose started to drive away, Mathews said after discussing how Tensing had reached into the car.

Tensing “wasn’t a racist,” said Mathews, adding he will present video of other Tensing traffic stops of black drivers, showing the officer to be professional and polite. If DuBose had cooperated with Tensing during the stop, he would not be dead, Mathews said.

During the traffic stop, Tensing asked DuBose to remove his seat belt and tried to open the car door. DuBose did not comply and closed the door. The vehicle started rolling forward slowly, and with his arm pinned against the steering wheel, according to his lawyer, Tensing pulled his gun and fired once.

Hamilton County Chief Assistant Prosecutor Stacey DeGraffenreid, in brief opening remarks, said on Thursday that Tensing ignored his training when he reached into the car and was never in any danger.

“Mr. Tensing was not trapped,” she said. “This is clearly a murder.”

The university police fired Tensing after he was charged. A mistrial was declared last November in the first trial after jurors could not agree on a verdict.

A jury of 12 people - seven white females, two white males, two black females and one black male - are hearing the case at the Hamilton County Courthouse.