MADISON, Wis. » Some of the Madison Police Department’s toughest critics peacefully protested in the hours after a prosecutor said he wouldn’t charge a white officer who killed an unarmed biracial man. But the city faced another test Wednesday as activists called for a widespread walkout.

After recent riots in cities where white officers have killed black men — including Ferguson, Missouri, and Baltimore — Dane County District Attorney Ismael Ozanne’s announcement Tuesday raised concerns that things could turn violent in Wisconsin’s capital city as well.

The Young, Gifted and Black Coalition, which called for the walkout, has staged multiple protests since Tony Robinson’s death on March 6. The group had demanded that Madison Officer Matt Kenny be fired and charged with homicide, but the rallies have been peaceful.

Ozanne, who is biracial but identifies himself as black, is Wisconsin’s first minority district attorney. He pointed out his racial heritage as he made the announcement, noting his black mother participated in the Freedom Summer, a black voter registration drive in Mississippi in 1964. He said he views Robinson’s death through that lens but made his decision based on the facts.

"I am concerned that recent violence around our nation is giving some in our community a justification for fear, hatred and violence," Ozanne said as he wrapped up his announcement. "I am reminded that true and lasting change does not come from violence but from exercising our voices and our votes."

Madison Police Chief Mike Koval said at a press conference Tuesday evening he was "hoping for a different sort of outcome in our community in the days to come" than what other cities experienced.

"I’m confident those outcomes can be more constructive," he said, according to the Madison State Journal.

On Tuesday, about 275 supporters joined Robinson’s family in a march to the Capitol after the announcement but dispersed peacefully long before sunset.

Young Gifted and Black wasn’t part of that rally. That group called on black people and students to walk out of work and school on Wednesday morning.

"YGB did not anticipate justice would be served by the same system that killed Robinson and continues to violently target Black and Brown people," the group said in a statement reacting to Ozanne’s announcement. "NO WORK. NO BUSINESS. NO SCHOOL. NO JUSTICE? NO PEACE," the group said on its Facebook page.

Koval clashed with the group for months before Robinson’s death, calling their demands that jail authorities release 350 black inmates and police leave black neighborhoods alone untenable. In his blog Tuesday, the chief offered a rundown of city ordinances governing demonstrations as well as what actions can lead to arrests. He did not mention Young Gifted and Black by name.

"I have no doubt that some individuals will make a principled decision to get arrested in order to make a definitive statement," Koval wrote. "That is, in fact, a hallmark of civil disobedience and that decision is highly personal and should not be coaxed from others as the consequences will only affect the violator."

The state Justice Department investigated Robinson’s death. According to witness accounts the agency compiled and released in reports after Ozanne announced his decision, Robinson was high on mushrooms the evening of March 6. He tried to grab a friend’s crotch in one of the bedroom’s apartments and took a swing at another friend in the living room. He also punched a man on the sidewalk outside the building, strangled another man at a gas station across the street, ran in and out of traffic and took a swing at a couple as they walked by before going back inside.

Kenny responded to 911 calls and found the apartment house door open. He heard what he believed to be a disturbance in the upstairs apartment and assumed the suspect involved in the street assaults was inside the unit and attacking someone else, according to the DOJ.

He drew his firearm and began to climb the stairs, he told a DOJ agent. He was near the top when he announced himself as a police officer. Robinson appeared and punched him in the head, knocking him into the wall, he said.

Kenny said he was worried Robinson would knock him down the stairs, take his gun, shoot him and then kill whoever was in the apartment. He fired seven rounds. Somehow both men ended up at the bottom of the stairs.

Another officer arrived and checked the apartment only to find it empty. Kenny rendered aid to Robinson.

"Stay with me. Stay with me," Kenny said he told him before paramedics took over. A responding firefighter told investigators it was clear Robinson was dead at the scene. As other officers led Kenny away, she heard him swearing to himself over and over.

He told the agency he couldn’t use nonlethal force because of "space and time considerations."

Ozanne said toxicology reports confirmed Robinson had taken mushrooms, smoked marijuana and taken Xanax, an anti-anxiety drug.

Associated Press writers Scott Bauer and Dana Ferguson contributed to this report.