After devoting the past few years organizing protests and calling for greater accountability from Chicago police, community activist William Calloway is bracing for the sentencing Friday of former officer Jason Van Dyke — the culmination of a case that could bring an end to a troubled chapter in the city's history.

For Calloway, who helped fight for the release of dashcam video that was instrumental in Van Dyke's murder trial, he remains anxious about the punishment to be handed down in the fatal shooting of black teenager Laquan McDonald and the message it will send to a community and law enforcement in need of an "honest reckoning."

"People want Jason Van Dyke to do virtual life in prison," said Calloway, 29, who was outspoken during neighborhood town halls ahead of last September's trial. "Anything less would not be justice for Laquan McDonald."

Van Dyke's defense team is asking for as little as probation, but the 40-year-old officer could get at least 18 years behind bars under the prosecution's request — what some activists still consider "nothing more than a slap on the wrist" — and as many as 96 years under sentencing guidelines.

The jury's guilty verdict, which followed three weeks of emotional and often jarring testimony, stunned many, including Calloway, who worried long-simmering racial tensions would spill over in the fallout of Van Dyke shooting McDonald 16 times during a confrontation on a South Side street in 2014. Van Dyke, who is white, said he feared for his life.

Activist Eric Russell, who is black, said a roughly 20-year sentence might seem sufficient, but he believes Van Dyke's duty to uphold the law as a police officer should be taken into consideration by Cook County Judge Vincent Gaughan.

"Why is it when black people are convicted of something much smaller they get beaten down with every letter of the law?" Russell asked. "We want to know that no one is above the law. That's the message that needs to be sent."

Murder or manslaughter charges against police officers for on-duty shootings are rare — there have been fewer than 90 since 2005 amid the hundreds each year, according to data compiled by The Washington Post's police shootings tracker as of July 2018. Less than half of those cases resulted in a conviction.

The last time a Chicago police officer was convicted of murder for an on-duty killing was more than 50 years ago.

Van Dyke's sentencing is set for a day after the bench trial for three Chicago police officers who were at the scene of McDonald's shooting and accused of interfering in the investigation to protect Van Dyke.

Officer Thomas Gaffney, former Detective David March and former officer Joseph Walsh, who was Van Dyke's partner, each pleaded not guilty and claimed that McDonald had been swinging a knife during the incident. But their reports were contradicted by the dashcam video that was released more than a year after the shooting following public pressure.

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The trio face conspiracy-related charges, the most serious of which carries a prison sentence of up to five years. A judge is set to decide Thursday whether they are guilty or innocent.

Legal experts and defense attorneys who spoke with NBC News said it's unclear how the judge in that case might rule and what it could signal for Van Dyke's sentencing.

Van Dyke was convicted of second-degree murder, which in Illinois suggests a prison term of no less than four years but no more than 20. But he was also convicted of 16 counts of aggravated battery — one for each gunshot.

That's where sentencing could get tricky, said Stephen Richards, a veteran defense attorney who was involved in a high-profile case in Gaughan's courtroom more than a decade ago.

Each count of aggravated battery carries a mandatory minimum of six years in prison and up to 30 years, and if the judge finds that each shot played a role in the killing of McDonald, then Van Dyke faces at least 96 years behind bars, Richards said.

Special Prosecutor Joseph McMahon wrote in a filing Monday that if any of the 16 shots contributed to "severe bodily injury," those counts should be subject to a consecutive minimum six-year sentence, meaning they must be served back to back.

Defense attorney Dan Herbert wrote in his filing that the judge should instead consider the second-degree murder charge when sentencing Van Dyke, which would allow for probation. Herbert has previously said that all of the 16 shots should be bundled as one — and if the judge decides to count any of them, Van Dyke should serve them concurrently at the minimum sentence of six years.

"It's an unusual situation and very difficult to predict what will happen," Richards said.

He doesn't expect Gaughan to make a larger political or societal commentary with his sentencing of Van Dyke, and that he is prone to taking into account a defendant's personal actions. Richards recalled Gaughan had presided over a drug case involving a father and son, and when he later addressed the son, who had been acquitted, Gaughan "was more personal. He basically said you got a break of a lifetime, so don't let this happen again."

Gaughan is an Army veteran who served in Vietnam, and during his more than 25 years on the bench has overseen major trials in the city, including the 2008 child pornography case against R&B singer R. Kelly.

Gaughan has been "invulnerable" in his post, and has an appreciation for those in uniform, Richards said, adding that could help Van Dyke, whose family wrote impassioned letters about life without their father since he was jailed after his conviction.

One of Van Dyke's young daughters told Gaughan that "my heart ripped out of my chest" on the day the jury's verdict was read.

David Erickson, a retired judge and director of the trial advocacy program at the Chicago-Kent College of Law, said it's precisely because Gaughan is "old school" that he may take issue with how a "police officer broke the law."

Judge Vincent Gaughan presides over the Jason Van Dyke hearing at the Leighton Criminal Courts Building in Chicago on Aug. 4, 2016. Nancy Stone / Chicago Tribune via AP

But the judge, he added, will also consider whether the sentence is enough to ensure society is protected, that it rehabilitates the defendant and serves as a deterrent to other similar shootings.

"The message here is pretty clear: Police officers have to be better trained, they can't overreact and maybe we need a new policy on lethal force," Erickson said.

"The trial showed that the system can work, as slow as it may be," he added.

Neither the police union nor a family representative for McDonald could be reached for comment this week.

Whatever happens, activists say, there still needs to be wider transparency and accountability with law enforcement, and a government and political system that adequately serves minority communities.

That's why Calloway, part of a wave of young African-American activists, said he has taken the additional step of running as an alderman in Chicago, where residents will go to the polls next month and also vote for mayor to replace Rahm Emanuel, who decided not to seek a third term.

Calloway said an equitable resolution in the Van Dyke trial is one way for the city to move forward, but it will also take ending the police department's long-standing "code of silence" that can protect internal malfeasance to repair the rift caused by the McDonald shooting.

"For years, I've been adamant that everybody — activists, too — are not against law enforcement. We're against unconstitutional law enforcement," Calloway said. "We just want to heal."