Don’t lie. If you do, you could be prosecuted and go to jail. That has long applied to the general public in police investigations. Cops cannot be exempt.

Tuesday, a grand jury and Special Prosecutor Patricia Brown Holmes delivered a message to Chicago Police officers about their obligation to come clean when fellow cops go astray or rogue.

It came via a damning indictment of three current or former cops involved in the investigation of the 2014 shooting death of 17-year-old Laquan McDonald by then-Chicago Police Officer Jason Van Dyke. Detective David March and Patrol Officers Joseph Walsh and Thomas Gaffney were each charged with conspiracy, official misconduct, and obstruction of justice for allegedly engaging in a cover-up to protect Van Dyke, who faces murder charges.

EDITORIAL

We are not making a judgment against the officers. That is up to the courts. We know, however, that reforms in the Chicago Police Department are long overdue.

The indictment alleges that March lied when he wrote in a case incident report that “McDonald committed aggravated assaults against the three officers, finally forcing” Van Dyke, “in defense of his life, to shoot and kill McDonald.”

Police video contradicts this depiction. McDonald jogged down the street, with a small knife in hand, and moved slightly away from officers just before Van Dyke fired at him 16 times.

The officers went beyond the unofficial “code of silence” that cops heed, Brown Holmes said in a statement. The “code” implies officers stay quiet about  mistakes or brutality by a fellow officer. According to the indictment, the officers “lied” about what happened so independent criminal investigators “would not know the truth about the Laquan McDonald killing and the public would not see the video recording.”

They gave false information, made false reports, failed to report or correct false information and failed to follow the law, the indictment says.

The wheels of justice are slowly turning in this case. We have come this far largely because of the video that a judge forced the city to release in 2015, more than a year after the shooting.

Craig Futterman, a University of Chicago Law School professor and police accountability advocate, told Sun-Times reporter Andy Grimm that the charges against the cops, like the murder charges against Van Dyke, are groundbreaking.

“If we want that culture (of silence) to end, and police officers want it to end, we have to know that there are consequences when officers lie,” Futterman said.

It shouldn’t surprise if more indictments follow. Asked about that possibility in a news conference Tuesday, Brown Holmes said more than once, “The investigation continues.”

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