Prosecutors have dropped 27 criminal cases worked on by a white police officer who was filmed appearing to attack a black man during an arrest.
US media reports said footage showed North Carolina officer Christopher Hickman choking and beating Johnnie Rush, who had been accused of jaywalking, and telling him he was “going to get f***ed up”.
Mr Hickman, 31, was arrested and charged with assault by strangulation after the video emerged last week.
Dozens of cases he initiated have since been shelved because the officer cannot be considered a credible witness, a district attorney said.
The video, recorded by Mr Hickman’s body camera, appears to show him and another officer talking to Mr Rush after stopping him in the city of Asheville on 25 August last year.
Mr Rush, 33, backs away and then runs off and is pursued by the officers, who tackle him to the ground.
“You know what’s funny is you’re going to get f***ed up hardcore,” Mr Hickman, who is then seen choking and hitting Mr Rush on the head.
“I can breathe, I can’t breathe,” says Mr Rush, who also screams in pain before he is stunned with a Taser.
Mr Hickman, who resigned from his job in January, was arrested last week after the footage was published by local newspaper the Citizen Times.
“The acts demonstrated in this video are unacceptable and contrary to the Department’s vision and the progress we have made in the last several years in improving community trust,” said Asheville police chief Tammy Cooper, in a statement issued on social media.
“Officers know that they must earn the trust of our community by providing fair and respectful service. That very clearly did not happen during the incident depicted and for that I apologise to Mr Rush, as well as the community.”
She added: “It is the policy of the Asheville Police Department to review all instances of use of force, and to take swift and immediate action upon any use of unwarranted or excessive force. The officer is no longer employed by the Asheville Police Department and a criminal investigation is underway that will be submitted to the District Attorney.”
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Buncombe County District Attorney Todd Williams told the Citizen Times the cases dropped involved 17 defendants and included felonies and driving offences. They did not include violent crimes or sex offences.
More cases could be dropped as prosecutors analyse convictions obtained using Mr Hickman’s testimony.
The FBI has also launched a criminal investigation into Mr Hickman, who will appear in court next month.
The footage of Mr Rush being attacked has sparked outrage in the city and prompted condemnation from civil rights groups.
“There is no excuse for what happened to Johnnie Rush,” tweeted the American Civil Liberties Union’s North Carolina branch. ”Police must protect and serve everyone, regardless of race. Instead, a black man gets beaten, tased, and choked over jaywalking. That’s right, jaywalking.”