MILWAUKEE — In a case that echoed growing tension over race and policing in other cities, a former Milwaukee police officer who fatally shot an African-American man this year will not face criminal charges, a prosecutor announced on Monday.

Nearly eight months after the death of Dontre D. Hamilton, Milwaukee County’s district attorney concluded that the officer, Christopher Manney, who is white, was defending himself when he shot and killed Mr. Hamilton in April. Witnesses said Mr. Hamilton had grabbed the officer’s baton during an encounter in a downtown park and hit the officer with it or was attempting to, the prosecutor found. Officer Manney fired at least 13, perhaps 14 times.

“This was a tragic incident for the Hamilton family and for the community,” John T. Chisholm, the district attorney, wrote in a 25-page presentation, which was accompanied by lengthy appendices, released on Monday morning. “But, based on all the evidence and analysis presented in this report, I come to the conclusion that Officer Manney’s use of force in this incident was justified self-defense and that defense cannot be reasonably overcome to establish a basis to charge Officer Manney with a crime.”

Image Dontre Hamilton Credit... Uncredited/Family photo courtesy of Dameion Perkins, via Associated Press

In this city, where the case had led to growing protests in recent weeks even before the decision was announced, members of Mr. Hamilton’s family said they were deeply disappointed and seeking a federal investigation. The United States attorney’s office for Eastern District of Wisconsin said Monday that the Justice Department would review the case.