In the hours and days after Chicago Police Officer Jason Van Dyke shot a 17-year-old boy to death, his fellow cops allegedly did all they could to make it seem as if he'd done nothing wrong.

That included falsely stating that the victim had assaulted the officers, ignoring witnesses who saw things differently and giving misleading descriptions of what video showed of the shooting, authorities charged on Tuesday.

As a result of those accounts, the shooting was deemed justified. But the video, which the city resisted releasing to the public for a year, blew that conclusion apart, exposing the alleged cover-up and forcing authorities to file murder charges against Van Dyke.

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The video showed Van Dyke shooting McDonald 16 times, sparking public outrage and leading to a probe by the U.S. Justice Department that ended with a report that documented years of systemic civil rights violations by the country's second-largest police department. The litany of abuses included officers' routinely shooting at fleeing suspects, using force to retaliate against people and purposefully botching probes into colleagues' misconduct.

The city began negotiating a court-enforced agreement to reform the police force, but Mayor Rahm Emanuel backed out of the talks this month.

Van Dyke, meanwhile, is waiting to go to trial.

Chicago police Officer Jason Van Dyke at a February hearing on the shooting of of Laquan McDonald. Antonio Perez / AP Pool

And a special Cook County prosecutor's investigation moved toward its conclusion.

That probe resulted in an indictment, unsealed Tuesday, that named Det. David March and officers Joseph Walsh and Thomas Gaffney as the leaders of a conspiracy to obstruct justice in the McDonald case. The conspiracy charge, as well as one of official misconduct, carry prison terms of up to five years. All three cops were expected to show up voluntarily for their July 10 arraignment.

March and Walsh have resigned from the force. Gaffney will be suspended without pay, as is customary for officers under felony indictment, a department spokesman said.

The city's police union declined to comment, citing the ongoing investigation.

But Van Dyke's attorney, Dan Herbert, said in a statement Tuesday night that the new indictment represented the real cover-up.

"The officers are charged with conspiring to ensure that 'the public would not see the video recordings of the event,'" Herbert said. "If true then the entire command staff of the police department, including the former and current superintendents, must be part of the conspiracy considering they were aware of the reports and video when they signed off on the shooting."

Police Superintendent Eddie Johnson said in a statement that McDonald's shooting "forever changed the Chicago Police Department" and that he remained committed to making sure something like it never happened again. His statement did not address the indictments.

"The indictment makes clear that these defendants did more than merely obey an unofficial 'code of silence,'" the special prosecutor, Patricia Brown Holmes, said in a statement. "Rather, it alleges that they lied about what occurred to prevent independent criminal investigators from learning the truth."

Related: Police Accounts Appear to Differ With Laquan McDonald Shooting Video

The indictment ─ which at times identified Van Dyke as "Individual A" ─ quotes from an array of reports written by the officers that gave untrue versions of what happened before and during the shooting on Oct. 20, 2014. The alleged lies included assertions that McDonald assaulted the three officers, swung a knife at them and, while Van Dyke was shooting him, tried to get off the ground with the knife still in his hand.

"MCDONALD committed aggravated assault against the three officers, finally forcing Officer [Individual A], in defense of his life, to shoot and kill MCDONALD," March wrote in one report, according to the indictment.

Later, the three officers submitted "virtually identical" reports on officer injuries, claimed they'd all been hurt in the confrontation.

Other officers, unnamed in the indictment, helped prepare the reports, the grand jury charged. Holmes said Tuesday that if the case went to trial, their names would be revealed.

When three witnesses gave information inconsistent with the version provided by Van Dyke's colleagues, the three officers didn't bother to follow up, the indictment alleges.

The officers also gave false descriptions of video to throw off investigators and block its public release, the indictment alleges.

In the end, the video may end up doing them in.