DES MOINES, Iowa (AP) — The city of Des Moines is acknowledging that a former police officer falsely told investigators she warned an unarmed man who approached her patrol car to "get back" before she fatally shot him.

Video and audio recordings of Vanessa Miller's patrol car show she didn't warn 28-year-old Ryan Bolinger before firing her weapon in 2015, The Des Moines Register reported . Miller acknowledged the disparity as part of a wrongful death lawsuit filed by Bolinger's family.

Miller was following Bolinger after he behaved erratically near another officer's traffic stop. Bolinger exited his vehicle and approached Miller. She said the look on Bolinger's face indicated he intended to harm her, leading her to shoot him through the closed driver's side window of her vehicle.

"I was very certain that I was yelling at him to get back," Miller said in a deposition tied to the pending lawsuit. "Obviously, in the audio, there's not that. And my only explanation for that is that it either — I just physically could not get it out of my mouth. In my head, I was screaming at him to get back."

Miller, who resigned from the department in July 2016, wasn't disciplined because of her misstatement to investigators, according to Des Moines Police Sgt. Paul Parizek.

"Cognitive distortions, including memory, are common in high-stress situations," Parizek said.

The city's attorneys said the circumstances of the shooting made making a warning unfeasible,

"The facts of the speed of the event, what Miller perceived, and the fact that she was behind a closed window, make such a warning unfeasible," city attorneys said.

Miller also was cleared of any police department policy violations, and a grand jury didn't find a basis for criminal charges.

Bolinger's family is suing the city for wrongful death, alleging the police department was negligent in training and supervising Miller. The lawsuit is schedule to go to trial in January 2018.

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Information from: The Des Moines Register, http://www.desmoinesregister.com