One of the clearer signs of this problem was literally a sign, the Justice Department said: a large banner hanging in a district police station that described the facility as a “Forward Operating Base” — the term the military uses for heavily guarded wartime outposts inside insurgent-held territory.

Released by Attorney General Eric H. Holder Jr. at a news conference in the sleek skyscraper that houses the main federal courts in downtown Cleveland, the report also found that the police frequently stopped and searched people without apparent cause, and that blacks widely believed the mostly white police force singled them out for verbal and physical aggression.

This was not news to Joseph McFarland, a school employee in his 20s, or his friends. He said he spent a night in jail after being stopped a few blocks from where Tamir Rice lived, for not having lights or reflectors on his bicycle.

“That’s not why they stopped me,” he interjected. “They stopped me because they were being racist.”

Like Mr. McFarland, his girlfriend, Samantha Teresi, said they knew many people their age that had been hassled or detained by the police.

“If you try to question them, they’ll arrest you, they’ll try to pin something on you,” she said, standing just steps from the Rices’ home. “They don’t like to be questioned. They don’t like it when you know your rights.”

The neighborhood has not seen the same economic revival that some other Cleveland sections have experienced. Just west is Lakewood, Ohio, which a few years ago was ranked by BusinessWeek as the best place in the state to raise children. To the east is the trendy Gordon Square Arts District, where new boutiques and restaurants have opened, and home prices are rising.