The Black Officer Who Detained George Floyd Had Pledged to Fix the Police

Growing up, Mr. Kueng and his family made repeated trips to Haiti, helping at an orphanage. Mr. Kueng and his siblings took a break from school to volunteer there after the earthquake in 2010.

Joni Kueng, 56, likes to say that the Kuengs are a family of doers, not talkers.

“I had to stay out of the race conversations because I was the minority in the household,” Ms. Kueng said in her first interview since her son’s arrest. She said that race was not an issue with her, but that she was conflicted. “It didn’t really matter, but it does matter to them because they are African-American. And so they had to be able to have an outlet to tell their stories and their experience as well, especially having a white mom.”

Ms. Kueng taught math at the schools her children went to, where the student body was often mostly Hmong, African-American and Latino. Classmates described Alex Kueng as friends with everyone, a master of juggling a soccer ball and a defender against bullies. Photos portray him with a sly smile.

Darrow Jones said he first met Mr. Kueng on the playground when he was 6. Mr. Jones was trying to finish his multiplication homework. Mr. Kueng helped Mr. Jones and then invited him into a game of tag.

When Mr. Jones’s mother died in 2008, Ms. Kueng took him in for as long as a month at a time.

By high school, Mr. Kueng had found soccer, and soon that was all he wanted to do. He became captain of the soccer team; he wanted to turn pro. The quote next to his senior yearbook picture proclaimed, “We ignore failures and strive for success.”

Mr. Kueng went to Monroe College in New Rochelle, N.Y., to play soccer and study business. But after surgery on both knees, soccer proved impossible. Mr. Kueng quit. Back in Minneapolis, he enrolled in technical college and supported himself catching shoplifters at Macy’s.

About that time, he started talking about joining the police, Ms. Kueng recalled. She said she was nervous, for his safety and also because of the troubled relationship between the Minneapolis police and residents.