A former vice squad officer in Ohio was charged Thursday with fatally shooting a woman who was sitting in his unmarked police vehicle in what the man says was an act of self-defense.

Columbus police say Andrew Mitchell shot and killed 23-year-old Donna Castleberry in August 2018 after she stabbed him in the hand during an undercover prostitution investigation.

Mitchell, 55, was indicted on one count each of murder and voluntary manslaughter. Mitchell's attorney, Mark Collins, said Thursday that Mitchell will plead not guilty.

Collins said the burden on prosecutors is to prove Mitchell wasn't acting in self-defense, and added that an internal Columbus police review determined the shooting was a proper use of force.

"He was stabbed first," Collins said. "There's no dispute about that."

The Columbus police department respects the decision to charge Mitchell, who resigned from the agency last month in bad standing, said Tom Quinlan, the acting chief.

"Andrew Mitchell's actions have cast a long shadow over the Columbus Division of Police," Quinlan said. "I am taking concrete actions to restore the public's trust."

Mayor Andrew Ginther said that prosecuting Mitchell is "essential both to protect our community and to support the many honorable officers whose reputations he has unfairly tarnished."

Castleberry's family has said that she had struggled with drugs and was likely working the streets as a prostitute at the time she was shot. She left behind two young daughters.

"There is no happy ending in this situation, but maybe there can possibly be a slightly better ending than what it could have been and this is a start," said Castleberry's cousin, Mary Laile.

The shooting happened in a parking lot behind an apartment building in an area known for prostitution. A month earlier, Castleberry had been arrested nearby on a misdemeanor soliciting charge after offering to have sex with an undercover officer for $50, according to court records.

A witness, Kaitlin Patton, previously told The Associated Press that she walked up to Mitchell's car after hearing several shots and saw Mitchell pushing Castleberry's folded-over body into the rear seat. Catching sight of Patton, Mitchell told her he was a police officer, that he'd been stabbed, and to call 911.

A coroner's report shows Castleberry was shot three times.

Police say Mitchell was under investigation for criminal misconduct before the shooting. He was relieved of duty with pay in October.

Mitchell is also facing federal charges filed last month on allegations he forced women to have sex with him under threat of an arrest, pressured others to cover up crimes and lied to the FBI by saying he'd never had sex with prostitutes. He has pleaded not guilty and Collins, his attorney, has described the allegations as unfounded. The FBI searched Mitchell's house Sept. 26.

The federal indictment accuses Mitchell, a 30-year veteran, of arresting two different women and forcing them to have sex with him before he would release them.

Later, during the federal investigation, Mitchell lied when he told the FBI he'd never had sex with a prostitute, since Mitchell knew "he has had sex with numerous prostitutes, including having paid women money for sex," according to the indictment.

Federal prosecutors also say multiple women who were tenants of Mitchell's rental properties traded sex for free or reduced rent from him, some of whom work as prostitutes and most of whom are drug addicts. All "are vulnerable members of our community," prosecutors said in a filing last month.

Collins has disputed these arguments, noting that Mitchell has not been charged with such crimes.

The charges against Mitchell were the latest mark against the embattled vice squad, which has also been under scrutiny since last year's arrest of porn actress Stormy Daniels. Charges against her were dropped hours later. The police department disbanded the unit last month, saying vice-related crimes will be handled differently and with a more community-based approach.

Earlier this year, Daniels sued several Columbus police officers for $2 million over that arrest. Daniels' federal defamation lawsuit alleges that officers conspired to retaliate against her because of her claims she had sex with Donald Trump before he became president.

Last month, an internal police investigation concluded Daniels' arrest was improper, but not planned or politically motivated.

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Follow Andrew Welsh-Huggins on Twitter at: https://twitter.com/awhcolumbus.