I fought Chicago city government in court in 2015 to release the video of 17-year-old Laquan McDonald being killed by a police officer. After a judge ordered the video released in my case, 405 days after the killing, prosecutors charged the officer, Jason Van Dyke, with murder. A jury convicted Van Dyke October 5.

It’s a strong message, the conviction of Jason Van Dyke. In at least 50 years, no Chicago police officer has been charged with murdering a citizen while on duty—let alone convicted. Judging by this verdict, if more police were charged, more would be convicted. At least a hundred killings a decade by Chicago police have gone without punishment. Without justice, some would say. How can we slow or stop it? I’ve outlined that below.

Laquan had a hard life. He was high the night he was murdered, and walking around, sometimes holding his knife and sometimes with it pocketed. (Talk to people from Laquan’s neighborhood and you’ll learn: guns are for violence. Knives are for protection.) He may have been out to steal a car radio, although he never got ahold of one.

None of this should have meant a death sentence, according to members of the jury that convicted Van Dyke. They found the former officer guilty on one count of second-degree murder and 16 counts of aggravated battery.

“Black boys needed that,” said a member of Laquan’s community, outside the courtroom after the verdict was read. “Black girls needed that.”

That night, Laquan had run away from police for a few minutes before he was surrounded by five police cars, totaling ten officers. When it was clear he wasn’t getting away, he slowed his walk and held his knife. Van Dyke had been following Laquan in a police car, but roughly six seconds after he jumped out, he opened fire, hitting the teen with all 16 bullets in his gun.

Since videos of the incident didn’t come with sound, the prosecution called an FBI expert to identify visual markers to determine how long Van Dyke was shooting. The FBI found “a minimum of” 14.2 seconds. Then they played a video, with sound, of a marksman shooting 16 shots into a target over exactly 14.2 seconds.

The painfully slow sound was devastating—horrifying—to those of us trying to understand how Laquan met his end. Maybe even more than the actual video.

A prosecutor asked the FBI expert: “How would you characterize the rate of fire?”

“It’s a deliberate rate of fire,” the expert said. “It’s methodical. He was taking time to aim each shot.” The prosecutor let that linger in the dead air of the courtroom. You could hear a pin drop.

In years past, several citizens had filed complaints alleging Van Dyke had used racial slurs in their interactions with them. The judge did not allow this to be presented to the jury in his trial.

One in three Americans killed by people they don’t know are killed by police, according to a study published in Granta magazine. The American Journal of Public Health declared that between 2012 and 2018, 8% of adult male homicide victims are killed by police.

Maybe after this verdict, more American juries will stop accepting an otherwise baseless “I feared for my life” by accused officers. And yet, darker-skinned people are still perceived as more scary than the lighter-skinned. If that doesn’t change, the excuse will still work, considering police tend to shoot people of color. Caucasians make up five percent of people police shoot in Chicago, a city that’s 32 percent caucasian.

The video prompted firings of a slew of officials and a slate of reforms is set to be approved by a judge. (Donald Trump’s attorney general says he opposes the reforms.) Mayor Rahm Emanuel announced the day before Van Dyke’s trial that he would not seek re-election. Emanuel had raised millions for his campaign and fielded ballot petitioners.

Every story about Rahm’s political prospects since the video’s release had mentioned the name “Laquan McDonald.”

And yet—replacing brass doesn’t replace a system. Police originally lied to the public, saying a single shot killed Laquan. The city and police opposed the video’s release. Offices that sought to hide how the boy died remain. Each worker in them can cite “that’s just how things work” or “I’m just doing my job”—instead of considering oneself, where responsibility lies.

Two witnesses to Laquan’s murder were arrested that night, taken to “central holding,” kept overnight, and intimidated. They were told over and over, according to a lawsuit one of them filed against the city, that “you didn’t see what you think you saw.” Several other witnesses have said they were “shooed away” and that police didn’t take their information.

If Chicago wants to stop police from killing so indiscriminately, Chicagoans need to dismantle officers’ ability to exonerate themselves and hide their colleagues’ misdeeds. When I filed my lawsuit for the video, with an attorney who only got paid by the state when he won, I was washing dishes in a restaurant.

Several, but not yet all, officers involved with protecting Van Dyke face charges in connection.

To police: if the public sees you purging repeat offenders from your ranks, Chicagoans might start to trust you again. And don’t let the Fraternal Order of Police convince you that transparency or accountability causes violence. This has been probed extensively and found untenable. Well-proven solutions haven’t been implemented at scale.

If only Laquan knew that night, as he breathed his last breaths, that his name would galvanize a mindset for an entire city. If only he were here to see it. To file a FOIA request. To march, with his schoolmates, for a better world.