A former Minnesota police officer was 'reckless' when she shot dead a black motorist in April, prosecutors said on Wednesday.
Kim Potter, 49, has said she mistakenly drew her gun instead of her Taser and killed 20-year-old Daunte Wright.
She now faces two manslaughter charges for his death. Her defence team claims he was resisting arrest at the time.
In court, Mr Wright's mother detailed their final conversation, minutes before he died.
In an emotional testimony on the first day of the trial, Katie Bryant said that her son "sounded really nervous" in a phone call just minutes after being pulled over.
She added that she heard a police officer tell him to hang up, followed by a scuffle before the call was disconnected. She made repeated attempts to call him back before his girlfriend finally answered.
"She [his girlfriend] said that they shot him and she faced the phone towards the driver's seat," Ms Bryant recalled. "My son was laying there. He was unresponsive."
Jurors were also shown footage of an extremely distraught Ms Bryant speaking to police officers at the scene of the shooting.
In other footage, Ms Potter could be heard repeating the word "Taser" several times before firing a shot from her pistol, and saying that she grabbed "the wrong gun". She is seen collapsing on to the pavement, crying.
In court on Wednesday, Assistant Minnesota Attorney General Erin Eldridge argued that Ms Potter - a 26-year veteran of the department - should have known the difference between a pistol and a Taser.
The case is about Ms Potter's alleged "recklessness and negligence" she said.
"Evidence will show she flouted her training and flouted [department] policy," Ms Eldridge told the jury.
The loaded pistol weighed more than twice that of the Taser, she said, adding that prosecutors believe Ms Potter failed to live up to her sworn duty as a police officer.
The former police officer's lawyer, Paul Engh, argued the shooting was an accident, not a crime, and appeared to suggest that some of Mr Wright's actions were to blame.
"All he had to do was surrender, but that wasn't his plan," Mr Engh said.
Ms Potter sought to tase Mr Wright because she feared for her partner's safety, the lawyer said.
"This is an accident. She is a human being," he said. "But she had to do what she had to do to prevent the death of a fellow officer."
Anthony Luckey - a Brooklyn Center Police Officer who was being trained by Ms Potter that day - testified that Mr Wright was pulled over after running the licence plate and finding it expired. He also had an air freshener dangling from the rear-view mirror, which is prohibited in Minnesota.
A police system check then revealed that Mr Wright had an outstanding warrant.
He said that Mr Wright "jerked his arm back" while being handcuffed and managed to get back into the vehicle.
Mr Luckey added that there was a scuffle with Mr Wright - who he said was holding onto the steering wheel - before the fatal shot.
Mr Wright's death on 11 April 2021 came amid already heightened tensions in the Minneapolis area during the trial of Derek Chauvin, the police officer later convicted of murdering George Floyd, an unarmed black man.
Under Minnesota state law, a person can be found guilty of second-degree manslaughter if it is proven that they demonstrated negligence by creating unreasonable risk and "consciously take chances of causing death or great bodily harm" to another person.