Laquan McDonald and Jason Van Dyke. View Full Caption Provided/Chicago Police

DOWNTOWN — Chicago Police officers lie so frequently during testimony, they've developed a term for it — "testilying" — according to a petition from city leaders and activists.

On Tuesday, a coalition of lawyers, political leaders and activists filed a petition in the Circuit Court of Cook County calling for State's Attorney Anita Alvarez to be replaced by a special prosecutor in the Jason Van Dyke case.

But the petition also claims there's evidence police participated in a coverup in the death of 17-year-old Laquan McDonald and says it's important those officers be prosecuted, though none have been charged.

McDonald was shot 16 times by Van Dyke in October 2014, but Van Dyke wasn't charged with murder until this November, just hours before a video of the shooting was released to the public.

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The petition alleges officers might have engaged in a coverup in the case to protect Van Dyke, saying there is evidence officers committed obstruction of justice, intimidated witnesses and tampered with a Burger King surveillance video of the shooting.

In December, DNAinfo.com Chicago reported that officers who claimed to witness the shooting gave official reports that conflict with action captured on dashcam video and had escaped punishment. Those officers also have a history of misconduct and have gone unpunished.

"There is reason to believe that the police reports documenting the McDonald shooting 'furnished false information' — specifically by falsifying the officers' own accounts of the shooting and by falsifying eyewitness accounts of the shooting," the coalition wrote in the petition.

Statements from officers who witnessed the shooting were similar to "false" statements from the Fraternal Order of Police and the Chicago Police Department, the coalition wrote.

Officers reported McDonald swung a knife in an "aggressive, exaggerated manner" at Van Dyke and, after being shot, held onto a knife as he tried to get up, according to the coalition. The video debunked this narrative.

The coalition also claims there is evidence witnesses of the shooting were "taken to the police station, held against their will, interrogated for hours and harassed and pressured by police to change their stories," the petition says. When witnesses wouldn't change their stories, police falsified their accounts in official reports, according to the coalition.

Other witnesses of the shooting were told to leave or they'd be arrested, the coalition wrote.

RELATED: McDonald Family Lawyers Accused Police of Threatening Eyewitness

None of the officers have been charged with obstruction or misconduct. The coalition pointed to that as evidence Alvarez is unable to fairly prosecute police, writing Chicago officers lie — called "testilying" — during testimony, falsify evidence and cover up misconduct and "virtually never face criminal charges."

"Perjurious testimony on the part of police is so common in the Cook County criminal court that the police casually and cynically refer to their sworn testimony as 'testilying,'" the coalition wrote in the petition.

"This state's attorney virtually never charges officers of the Chicago Police Department with perjury, obstruction of justice or official misconduct when they lie on the witness stand, prepare provably false reports, fabricate evidence, destroy or conceal evidence or coerce witnesses — despite the unfortunate regularity with which such misconduct occurs."

A DNAinfo analysis found officers who were caught lying during an investigation were often protected by the city and rarely punished.

"The Chicago Police Department is fully cooperating with a U.S. Department of Justice investigation into the incident as we feel there is no better way to determine if wrongdoing occurred," said Frank Giancamilli, a Chicago Police spokesman, in an emailed statement.

Interim Supt. John Escalante has previously said officers should be fired if they are found to have lied about the shooting.

The petition was supported by the City Council's Black Caucus, the Cook County Bar Association, several aldermen, the Rainbow PUSH Coalition and a bevy of other political and religious leaders.

Related:

• Rule 14 and Cops Who Lie, Testing the Public Trust

• Not All 'Career Killer' Rule 14 Violations End with Firing

• Rule 14's Slow Road to Justice for Police Who Lie

• Rule 14: How Police Lies Change Lives

Read the petition here:

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