If convicted, Tensing could go to prison for life, Hamilton County Prosecutor Joe Deters said in a news conference. Deters played body camera footage of the traffic stop shooting that appeared to contradict Tensing's version of what happened.
"I've been doing this for over 30 years. This is the most asinine act I've ever seen a police officer make -- totally unwarranted," said Deters. "It's an absolute tragedy in the year 2015 that anyone would behave in this manner. It was senseless."
The prosecutor, who said he was shocked when he first saw the video, was adamant DuBose, who is black, had not acted aggressively toward Tensing, who is white.
"People want to believe that Mr. DuBose had done something violent towards the officer -- he did not. He did not at all. I feel so sorry for his family and what they lost, and I feel sorry for the community, too," Deters said.
A reporter asked Deters whether he thought Tensing tried to mislead investigators looking into the incident.
"Yes," he said. "I think he was making an excuse for a purposeful killing" of DuBose, who was unarmed.
'Feared for his life'
Tensing fatally shot DuBose, 43, during a July 19 traffic stop over an alleged missing license tag. The officer has said he was forced to fire his weapon after almost being run over.
His body camera video captured Tensing telling officers after the shooting: "I think I'm OK. He was just dragging me. I thought I was going to get run over. I was trying to stop him."
He says his hand was caught in DuBose's car, and later left the scene with another officer to go to the hospital to get checked out. The footage shows no one rendering aid to DuBose.
Tensing, 25, surrendered to authorities shortly after news of the indictment broke, and he is expected to be arraigned on Thursday. He has been fired from his job.
Tensing's attorney told reporters that he believes the officer feared for his life.
"The guy jams the keys in the ignition," Stew Mathews told CNN.
"Turns the car on, jams it in the drive and mashes the accelerator. He wasn't slowly pulling away. (Tensing) feared for his life. He thought he was going to be sucked under the car that was pulling away from him. He thought he was going to get sucked under and killed."
The officer's account was contradicted by Deters, the prosecutor, who said that Tensing was not dragged.
"This just does not happen in the United States. People don't get shot for a traffic stop unless they are violent towards the police officer, and he (DuBose) wasn't," Deters said. "He was simply slowly rolling away. That's all he did."
'Huge first step'
DuBose's death is the latest in a string of controversial killings of people by police that include Tamir Rice in Cleveland, Michael Brown in Ferguson, Missouri, and Walter Scott in North Charleston, South Carolina.
The people killed in each case have been black.
DuBose's mother told reporters that she is grateful "everything was uncovered" in her son's shooting.
"I want everybody to just lift up their heads in prayer, and thank God because this one did not go unsolved and hidden," said Audrey DuBose. "We're going to continue to fight together with God."
Terina Allen, DuBose's sister, said she believed all along the body camera video would vindicate her brother.
"My brother is one year younger than me, and I've known him his whole life. And I've known him to never ever to run from a police officer. His record, as bad as anyone wants to make it, proves he has no problem being arrested," she said.
Mark O'Mara, an attorney for the family, said he does not believe there would have been an indictment if there hadn't been video of the shooting.
"We've now made a huge first step because -- in a situation where sometimes people believe that officers are not held accountable for their actions -- in this case, one is being held accountable. So Cincinnati is showing the rest of us how to do this right," O'Mara said.