MINNEAPOLIS (AP) — Kim Potter’s use of deadly force against Daunte Wright was not appropriate, a use-of-force expert testified Wednesday at the former suburban Minneapolis police officer’s manslaughter trial, undercutting a defense argument that she would have been justified in shooting Wright even if she didn’t mean to.

“The use of deadly force was not appropriate and the evidence suggests a reasonable officer in Officer Potter’s position could not have believed it was proportional to the threat at the time,” said Seth Wayne Stoughton, a professor at the University of South Carolina School of Law.

Potter, who resigned from the Brooklyn Center police force two days after she shot and killed Wright, has said she meant to pull her Taser instead of her gun after Wright attempted to drive away as officers tried to arrest him on an outstanding weapons possession charge.

The defense has called the shooting a horrific mistake, but has also asserted that Potter would have been within her rights to use deadly force on Wright because he might have dragged another officer with his car.

Prosecutors, who are nearing the end of their case, have tried to portray Potter as an officer whose intended use of a Taser would have violated her department’s policy despite her extensive training.

Potter, 49, is charged with first- and second-degree manslaughter in the killing of Wright, who was pulled over on April 11 for having expired license plate tags and an air freshener dangling from his rearview mirror. Video captured the moments when Wright pulled away from officers who were trying to arrest him on the outstanding warrant, with Potter shouting “I’ll tase you!” and then shooting Wright with her handgun.

Potter is white and Wright was Black, and his death set off several nights of angry protests in Brooklyn Center. It happened while a white former officer, Derek Chauvin, was on trial in nearby Minneapolis for the killing of George Floyd.

Stoughton also testified at Chauvin’s trial, saying he judged Chauvin’s actions against what a reasonable officer in the same situation would have done and repeatedly found that Chauvin acted excessively when he held Floyd facedown with a knee across his neck for more than nine minutes.

On Wednesday, Stoughton reminded jurors that Potter warned that she was about to use her Taser on Wright, and said a reasonable officer would not have decided to use a Taser if they thought there was an imminent threat of death or great bodily harm.

What’s more, Stoughton said, “a reasonable officer in that situation would not have believed” those threats existed.

Stoughton said deadly force would have been inappropriate even if Potter believed another officer was in the car because of the risk that nearby officers or Wright’s passenger could get shot.

And he said that if it appeared Wright was going to drive away, shooting would make things worse because he could be incapacitated and the vehicle itself would become a weapon. After Potter shot Wright, his car drove a short distance down before colliding with another car and injuring several people. Stoughton said the use of a Taser would have been inappropriate for similar reasons: If Wright was incapacitated, the vehicle could turn into an unguided hazard, and if he wasn’t, he’d have been motivated to flee.

Under either situation, “the results are not good for the police,” he said.

Earlier Wednesday, a use-of-force and Taser instructor from the Brooklyn Center Police Department testified that officers are allowed to use deadly force to stop fleeing suspects.

Sgt. Mike Peterson testified under cross-examination by one of Potter’s attorneys that officers are trained to provide a warning before they use their Tasers, such as saying “I’ll tase you.” He also agreed under questioning from the attorney that officers can use Tasers against suspects who are violent or physically resisting.

Peterson said the decision on whether to use a Taser or any other type of force “has to be made in a very short amount of time” and that there have been other instances around the country in which officers confused a gun for a Taser.

“Mistakes can happen when someone confuses a Taser with a gun?” Potter attorney Paul Engh asked Peterson.

“Correct,” Peterson said.

Stoughton testified later that he knew of only 20 such cases, but defense attorneys used objections to prevent him from talking about how significant that was to Potter’s case.

On Tuesday, Brooklyn Center Police Commander Garett Flesland testified that Potter was trained on policies as they evolved during her 26-year career and repeatedly signed documents acknowledging the policies. Prosecutors introduced several documents that Flesland testified showed Potter’s repeated certifications on Taser training, and her awareness of the warnings for their use — including a certification the month before Wright was shot.

Peterson on Tuesday also walked jurors through the Brooklyn Center department’s training procedures for using Tasers as prosecutor Matthew Frank showed them pages from the manufacturer’s and the department’s training materials that warn against the dangers of mixing up a Taser and a handgun. Frank also highlighted portions that say a Taser should not be used simply to stop fleeing suspects or on suspects who are operating vehicles.

Judge Regina Chu ruled Tuesday that if Potter is convicted of one or both of the manslaughter counts against her, she would preside over a separate trial to determine if there were aggravating factors that would allow Chu to give Potter a sentence above what the state’s guidelines suggest.

State sentencing guidelines call for just over seven years in prison upon conviction of first-degree manslaughter and four years for second-degree, though prosecutors have said they plan to push for longer sentences.

The case is being heard by a mostly white jury.