Laura Morask, one of Commander Evans’s lawyers, called the review board “inept, corrupt and at times comically laughable,” and said its investigation was “incredibly, horribly flawed.”

“The display that we saw over the last few days is nothing short of disgusting, and it should be condemned,” she said last week of the state’s case, which presented many of the review board’s findings as evidence.

After the hearing, Commander Evans left the courtroom and walked to a staircase with reporters and police officers. At one point in the stairwell, he pointed to a reporter and called him “disgusting.” At another point, Commander Evans, who is black, said, “They think all black people are criminals, they think all cops are corrupt,” but it was not clear whom he was referring to.

Ms. Morask said that her client was “extremely happy” with the verdict, but that she did not know whether Commander Evans, who she said was eligible for retirement, would return to active duty. She said he was “one of the most effective police officers” in the city and had spent his career “getting rid of crime and gangs.”

But Stephan Blandin, a lawyer for Mr. Williams, criticized the verdict and said the judge “went out of her way in this case to give every benefit of the doubt” to the commander. “How do you ignore DNA evidence?” he said.

Anita Alvarez, the Cook County state’s attorney, said in a statement that she stood “strongly behind the decision” to bring charges against Commander Evans. Up for re-election next year, she has been criticized by protesters who see her as slow to act on issues of police misconduct.

“This case underscores the reality that it is extremely difficult to convince judges or juries in Cook County and around the country to convict police officers of misconduct in the line of duty, despite the fact that this victim made an immediate outcry and we had DNA evidence to support our case,” Ms. Alvarez said.