A Wisconsin prosecutor announced Tuesday that he will not file criminal charges against a white police officer who shot a Black man in the back in Kenosha last summer, leaving him paralyzed and setting off sometimes violent protests in the city.

Officer Rusten Sheskey’s shooting of Jacob Blake on Aug 23, captured on bystander video, turned the nation’s spotlight on Wisconsin during a summer marked by protests over police brutality and racism.

More than 250 people were arrested in the days that followed, including 17-year-old Kyle Rittenhouse, a self-styled medic with an assault rifle who is charged in the fatal shootings of two men and the wounding of a third.

Kenosha County District Attorney Michael Graveley said Tuesday that he “would have to disprove the clear expression of these officers that they had to fire a weapon to defend themselves.” He added: “I do not believe the state ... would be able to prove that the privilege of self-defence is not available.” Graveley said he had informed Blake of the news before a news conference to announce the decision.

Ben Crump, an attorney for Blake’s family, expressed disappointment with the decision, saying it “further destroys trust in our justice system” and sends a message that it is OK for police to abuse their power. He said he will continue to move forward with a lawsuit and fight for systemic change in policing.

“We feel this decision failed not only Jacob and his family, but the community that protested and demanded justice,” Crump and his co-counsel said in a statement, adding: “We urge Americans to continue to raise their voices and demand change in peaceful and positive ways during this emotional time.” The Blake shooting happened three months after George Floyd died while being restrained by police officers in Minneapolis, a death that was captured on bystander video and sparked outrage and protests that spread across the United States and beyond.

The galvanised Black Lives Matter movement put a spotlight on inequitable policing and became a fault line in politics, with President Donald Trump criticizing protesters and aggressively pressing a law-and-order message that he sought to capitalize on in Wisconsin and other swing states.

Kenosha, a city of 100,000 on the Wisconsin-Illinois border about 60 miles north of Chicago, was braced for renewed protests ahead of the charges, with concrete barricades and metal fencing surrounded the Kenosha County Courthouse and plywood protecting many businesses.

The Common Council on Monday night unanimously approved an emergency resolution giving the mayor the power to impose curfews, among other things, and Gov. Tony Evers activated 500 National Guard troops to assist.