For its part, Officer Van Dyke’s defense team showed jurors its own video. It used laser-based technology to create an animation that, the team said, depicted what the events would have looked like from Officer Van Dyke’s perspective. Taking the stand in his own defense, Officer Van Dyke testified, emotionally at times, that the dashboard camera video had not captured all that he could see that night. Laquan had a menacing look in his eye, the officer said, and angled the knife in his direction. Witnesses for the defense also spoke of Laquan’s behavior in the past, saying he had acted up while in juvenile detention and used drugs, though witnesses conceded that Officer Van Dyke did not know Laquan and would have known nothing about his background when he shot him.

Calling Laquan “the author, the choreographer of this story,” Daniel Herbert, Officer Van Dyke’s defense lawyer, said that his client acted reasonably and lawfully when he opened fire.

“Police are here to serve and protect,” he said. “They can’t retreat. They can’t run away like us.”

As the jury began deliberations on Thursday afternoon, attention to the trial, which has been live-streamed on local news websites for days, has seemed mixed. Some people said the years it had taken to get to trial had made the issue fade some, and that they were only vaguely aware. Others, particularly in some of the South Side’s predominantly black neighborhoods, said they were closely following the proceedings. Chicago, which has long wrestled with segregation and gun violence, has roughly equal numbers of white, black and Hispanic residents.

“Him getting off would just be almost a confirmation to a lot of people of color who feel like we are devalued here, we are discriminated against here,” said Asiaha Butler, a resident association leader in Englewood, a South Side neighborhood. “There’s so much racial bias here that no one wants to unpack and talk about.”

Some residents said it was unfair that unflattering parts of Laquan’s past had been a focus of attention but Officer Van Dyke’s past had not. There were indications that Laquan’s life might have been steadying before he died: His mother was working to regain custody, and his school principal said he was “coming every day, joking and even giving hugs.” Records show that Officer Van Dyke had at least 18 citizen complaints, including allegations of racial slurs and excessive force. In each case, he denied wrongdoing and was not disciplined.

Fallout from the video has forced changes in the Police Department, including new rules for use of force. But people in Englewood said little felt different.