The night of Oct. 20, 2014, Jason Van Dyke shot Laquan McDonald 16 times. Almost as soon as the shooting stopped, special prosecutors say that his fellow officers swung into action — in a conspiracy to protect Van Dyke from punishment for the shooting.

Last month, nearly four years after McDonald was killed, Van Dyke was found guilty of second-degree murder in an historic verdict — the first time a Chicago Police officer had been convicted of murder in an on-duty shooting in more than 50 years.

On Tuesday, three Chicago Police Department officers will go on trial in the alleged cover-up that followed the shooting, a case that activists say may have more impact on the department and the city than the guilty verdict against Van Dyke.

Special Prosecutor Patricia Brown Holmes — a former federal prosecutor and Cook County judge — leads a team of private attorneys who in 2017 filed charges of obstruction of justice and criminal conspiracy against three officers: Thomas Gaffney, one of the first officers to encounter McDonald the night of the shooting; Joseph Walsh, who stood just a few feet away from Van Dyke as he opened fire on the 17-year-old; and David March, the homicide detective who led the investigation of the shooting for the CPD.

The indictment alleges the three men filed false reports that said McDonald assaulted Gaffney, Walsh and Van Dyke and which portrayed the 17-year-old McDonald as moving aggressively at the officers before he was shot — an account that contradicts dashboard-camera video of the shooting.

The case is an indictment of the way the department has handled accusations of misconduct, large and small, for decades, said activist and independent journalist Jamie Kalven, who sued the city to get access to the dashcam footage.

“Obviously, it’s appalling when an officer shoots somebody without justification,” Kalven said. “Those shootings happen too often, but it’s still so rare. The kind of creative writing we saw in (the Van Dyke) case where reports are falsified to create an official narrative that defies reality, we have reason to believe that happens all the time. And that’s what this case is about.”

Van Dyke was charged with first-degree murder on the same day the video was released to the public in November 2015, and soon after, activists and civil rights attorneys, led by lawyers Locke Bowman and G. Flint Taylor, petitioned the presiding judge to appoint a special prosecutor to investigate the actions of the officers who were with Van Dyke the night of the shooting and those involved in the investigation that — back in 2014 — had cleared Van Dyke of wrongdoing.

Holmes’ team, which includes fellow former federal prosecutor Ronald Safer, has largely spelled out in pre-trial filings the evidence they intend to bring against Gaffney, Walsh and March at trial. The three officers were charged after a year-long investigation by Holmes and her team. While none of their peers in blue was charged in the conspiracy, a pre-trial motion describing the conspiracy includes anonymously identified fellow officers who also allegedly made false statements in reports or who signed off on those reports.

Prosecutors noted that Gaffney testified before a federal grand jury that he and the other officers at the scene — including Van Dyke — met with March at Area Central Headquarters and talked about the shooting together, before March took their statements in one-on-one interviews. Gaffney’s partner, Joseph McElligott, told the grand jury the officers watched the dashboard camera video of the shooting.

Another officer at the scene, Dora Fontaine, is expected to testify that March coached her during her statement to back up Van Dyke’s claim that McDonald was moving toward Van Dyke when he fired. Fontaine and McElligott, who both testified for the prosecution in Van Dyke’s trial, are expected to take the stand again for Holmes’ team.

Lawyers for the three officers have dismissed the idea of a coordinated effort to protect Van Dyke, and in a hearing last month, Walsh’s lawyer, Todd Pugh, said the seemingly false information in the reports was a minor, non-criminal matter.

“What this case really comes down to, as we listen to (prosecutors’) argument, is what we refer to around here as a good case with a little bit of bad paper,” Pugh said.

Holmes’ team also uncovered emails from March’s supervisors that point to a wider conspiracy, though it’s not clear how incidents in the investigation that don’t involve the three defendants will figure in the case at trial.

Court filings by the prosecution indicate that March’s supervisors, Sgt. Daniel Gallagher and Lt. Anthony Wojcik, had decided to clear Van Dyke early in the investigation. Gallagher wrote to Wojcik that “we should be applauding (Van Dyke) not second-guessing him” and suggests that McDonald “chose his fate. Possible suicide by cop.”

In May 2015, emails indicate another detective, who had been in communication with the union that represents most of the department’s rank-and-file officers, contacted Gallagher to report the Law Enforcement Legal Defense Fund was interested in taking up the potential legal defense of Van Dyke.

Another email sent by Gallagher a few weeks later shows that Wojcik also was communicating with the Legal Defense Fund, according to the prosecution’s filings. Gallagher and Wojcik could not be reached for comment.

Van Dyke was cleared of wrongdoing by the department, and while Holmes’ team repeatedly references an FBI investigation into the shooting and a federal grand jury convened in the case, no officer faced charges until then-State’s Attorney Anita Alvarez filed murder charges against Van Dyke more than a year after the shooting.

The apparent involvement of command staff in signing off on reports that differed from video evidence to clear an officer of an allegation of wrongdoing implicates the entire CPD in the so-called “code of silence” that has been alleged in misconduct cases and lawsuits for years, Kalven said.

“This is how systems change. Prior to this, you had officers told to cover for other officers, and only the refusal to go along was punished,” Kalven said. “It’s possible to feel sympathy for these officers. They’re the ones that are standing there when the music stops. Before this case, this is customary, this is what’s going to happen, this is how we’re going to handle this, this is what we’ve always done.”