The four teenagers drove around playing a game of Nerf Gun Assassin on a May evening before graduation in 2013. One of them randomly fired an orange dart out the window.

It was a stupid teenager move. What happened next was deadly serious: Two Minneapolis police officers pulled up, pointed their guns at the teenagers and shouted orders laced with expletives, two of them later recalled.

Kristofer Bergh, then 17, said he kept telling himself not to move suddenly or give the police any reason to shoot him. The youth who had fired the dart was steered into their cruiser for what seemed like an hour, and the officers seized everyone’s Nerf guns. One officer made a lasting impression; in fact, Mr. Bergh and another passenger said they would never forget him, nor what he said as he gave them back their guns.

“Most of you will be 18 by the end of the year,” the officer said, before letting them go. “That means you’ll be old enough for ‘big boy jail.’”

The roadside encounter with the four teenagers led to a complaint against Mr. Chauvin, and it reflected what both co-workers and citizens told The New York Times about encountering the officer over his 19 years with the Minneapolis Police Department: Mr. Chauvin did his job as if he were playing a role — a tough Dirty Harry on the lookout for bad guys.

“He was overly aggressive and not understanding that we were just kids,” recalled Noah McGurran-Hanson, who was in the car with Mr. Bergh and the two others, all of whom are white. “He was treating us like we had been tried and convicted.”