"All he has to do is stop and he would be with us," defense attorney Paul Engh told jurors. "She can't let him leave because he's going to kill her partner."

When Daunte Wright was being arrested, he freed himself from the officers' grip and tried to get back in his vehicle.

The defense argued that she meant to pull out and shoot her stun gun but instead, she accidentally pulled out her firearm.

Engh argued that Kim Potter was pulling out her stun gun with the intention of stopping Wright from driving away. He said that her partner, Sgt. Michael Johnson, was partially in the car. Engh said that Potter knew that if Wright drove away, Johnson would've been dragged alongside the vehicle.

Fleeing an officer is a "dangerous felony," Engh said. "It's a crime of violence."

The defense said it plans on introducing Dr. Laurence Miller, a psychologist, to testify about traumatic incidents, police work and action errors, which defense attorney Paul Engh said will be "about how it is that we do one thing while meaning to do another."

The defense is arguing that the fatal shooting was an accident and that Kim Potter meant to reach for her stun gun and not her firearm when she shot Daunte Wright in the chest.

Engh gave examples of common mistakes to the jury -- including writing the wrong date down or putting in an old password into a computer.

"They are ordinarily dismissible, but they become quite important when what happens is catastrophic," Engh said.

"Dr. Miller will tell you in times of chaos, acute stress decisions have to be made when there is no time for reflection," he added. "What happens in these high catastrophic instances is that the habits that are ingrained, the training that's ingrained takes over. In these chaotic situations, the historic training is applied and the newer training is discounted."

Engh said that stun guns have only been available in the last 10 years to the department and this is a brand new stun gun, "whereas, by comparison, Potter has 26 years of gun training. And an error can happen."

Defense attorney Paul Engh told the jury details about former Brooklyn Center officer Kim Potter, who has pursued a career in law enforcement since she was a teenager in high school.

Engh said that Potter got a bachelor's degree in criminal justice and sociology, and started her career in 1995 as a patrol officer for Brooklyn Center Police Department.

The 26-year veteran to the BCPD, Engh said, "always wanted to be on the streets."

"She'll tell you one of the proudest days of her life was to have her dad pin the badge on her so that she can be a police officer," Engh said.

In particular, Engh said Potter wanted to help domestic abuse victims.

"As she became a part of Brooklyn Center domestic abuse task force … she shepherded women through the court system, became mentors, and made sure they were treated fairly," Engh said.

Prosecutor Erin Eldridge told the jury more about 20-year-old Daunte Wright.

"Daunte Wright himself was just 20 years old -- just out of his teens -- still had a close relationship with his mother, had a new baby boy, a loving family and his whole adult life ahead of him," said Eldridge.

She told the jury that he had a large family that he loved, dreams of being a professional basketball player and plans to enroll in a trade school.

The prosecution is expected to have a "spark of life" witness, a Minnesota legal allowance that lets prosecutors present evidence about a murder victim that paints them in a nuanced light, legal experts say.

-ABC News' Sasha Pezenik contributed to this report.