Since late 2015, the public has known that police who witnessed the fatal shooting of Laquan McDonald described a scene starkly different than the one that later emerged on video of a white officer pumping 16 bullets into the black teenager.
The announcement Tuesday that three officers have been charged with lying about that night raises questions about why it took so long to bring charges and underscores how tough it is to battle the code of silence long associated with the Chicago Police Department and other law enforcement agencies across the country.
"Even though the police brass had seen this video, knew what was on it, each of the reports of these officers was approved all the way up the chain of command," said Craig Futterman, a University of Chicago law professor who has studied the department and was part of the legal team that fought the city over its refusal to release the video.
The officers who knew there was a video, he said, knew they could lie because "the CPD has allowed that for far too long."
Not until November 2015, more than a year after the Oct. 20, 2014, shooting and well after the city agreed to pay McDonald's family $5 million to avoid a lawsuit, did the city release the video. Officials acted only after a judge ordered them to do so.
The fact that there was a video and that video was released, said Futterman, is the only reason Officer Jason Van Dyke faces a charge of first-degree murder and the only reason why the other officers now face obstruction of justice and conspiracy charges.
Without the video, if McDonald had lived, "he would have been charged with aggravated assault or attempted murder," he said, based on the officers' reports that alleged McDonald raised his arm as if to stab Van Dyke with a knife and attempted to get up from the pavement, still armed with the knife, after he was shot.
Another legal expert said that while she doubts the three officers would have been charged without the video, the fact that they were charged based on obvious discrepancies between their reports and the video sends a powerful message to both police and the public.
"People on the scene get the message that the officer may not be indicted for pulling the trigger, but you could be for lying about it," said Christy Lopez, a Georgetown University law professor who led a federal probe of the city's police force.
The Justice Department in January released a scathing report that found that Chicago police had for years used excessive force, violated people's constitutional rights and operated in an environment where there was little chance they would be disciplined for lying.
As for the public that has grown increasingly skeptical that anything can be done to fight the code of silence that protects officers who break the law, Lopez said the indictment offers hope.
"How do you break through this" code of silence? she asked. "You hold police in very public ways accountable in very public cases."
She suggested that convictions of officers can only encourage the predominantly black and poor neighborhoods that are most suspicious of police.
"It will show the communities in the city that have felt disregarded by police that the city's power structure is trying to protect them," she said.
But, she said, convicting these officers could be difficult, as has been shown in recent verdicts involving videotaped police shootings in Minnesota and Milwaukee. In both those cases, officers were acquitted. A mistrial was declared last week in the trial of an officer in Cincinnati.
In prosecutors' favor is that the alleged lies were included in reports written hours or days after the shooting and not in the minutes after Van Dyke shot the teenager, when it might be more reasonable to believe the officers were confused.
"People will be able to see how the officers had the time to think about doing the right thing and they just failed," she said.
However, Lopez said, jurors might be reluctant to convict officers of a crime at the scene of a shooting if officers who actually pulled the trigger are being acquitted. The most serious charge carries a maximum sentence of five years in prison.
"We are more willing to send people away to prison who we can't identify with," she said. "But when you imagine them as you, professionals with families, it is a lot harder to send them away."
The issue of what was said in the immediate aftermath of the shooting was at the center of a court hearing Wednesday in which one of the three officers — retired Detective David March — and Van Dyke testified.
Van Dyke's attorneys were trying to prevent prosecutors from using some of his statements, arguing that he only spoke to detectives and his supervisors because he believed he would be fired if he did not.
But the Chicago Sun-Times reported that March testified that he never told Van Dyke he would be disciplined if he refused to answer his questions. The judge ruled that prosecutors could use Van Dyke's statements to March but conversations he had with a deputy chief could not be used.