Nearly two dozen Chicago police officers have been called before a federal grand jury, which is investigating the death of 17-year-old Laquan McDonald, shot by a fellow officer 16 times in 2014.

After a judge ordered the public release of police dashcam video of the incident last November, the shooting of the African-American teen became a spark that set off protests that still haven’t subsided in the Windy City.

As soon as the video was made public, it became clear that written police reports of the incident did not conform to the video, and despite that, the city ruled the shooting justified. Early in 2015, the Cook County State’s Attorney charged Jason Van Dyke, the officer who shot the teen, with murder. A grand jury is working on that charge.

But a federal grand jury has also been empaneled to determine if any civil rights violations occurred, and this month, 23 CPD officers have been called to testify about their experiences during the shooting.

Four of the officers called had filed written accounts that seem to be contradicted by the dashcam video.

Many of the written reports filed in 2014 by officers on the scene, including officer Van Dyke, claimed that the teen had been advancing toward officers in a threatening manner with a knife in his hand just before Van Dyke fired his weapon 16 times, killing the teen. The dashcam video, however, shows the teen with his arms down at his sides and stepping away from the officers.

Other reports have accused the CPD of going even further than merely filing allegedly false written reports.

A recent release of city communications seems to show that officers attempted to coerce witnesses to alter their own statements. Reports said three witnesses insist that, in the hours after the shooting, they were pressured to alter details of their story to conform to the accounts being given by the officers on the scene.

But the death of the teen has been roiling the city for months, causing serious political fallout for Chicago Mayor and former Obama Chief of Staff Rahm Emanuel.

In fact, after the video was released, the obvious conflict between what is seen on video and the written police reports immediately brought charges that Mayor Emanuel delayed the release of the video because an earlier release might have endangered his 2015 re-election campaign. His re-election was so contentious that he was forced into a runoff election for the first time in the city’s history, and that occurred despite his $30 million re-election campaign war chest.

Emanuel has denied the charge and, since the middle of last year, has also maintained that he was unaware about just how damning the dashcam video was. But Emanuel administration emails have also emerged that seem to tell a different story.

The emails seem to show that Emanuel’s office had worked overtime to keep the dashcam video under wraps for at least five years after his re-election. Emanuel’s staffers also allegedly tried to cajole the family of the teen who were engaged in negotiations for a five million dollar settlement with the city to accept a deal that would have mandated that the video stay out of the public eye.

The emails also seemed to show that Emanuel’s office was working other angles to quash the video. According to the emails, at least one member of Emanuel’s team was attempting to coordinate with the purportedly independent agency that is supposed to investigate police conduct.

Follow Warner Todd Huston on Twitter @warnerthuston, or email the author at igcolonel@hotmail.com.