People stand in prayer after marching about a mile to the police station to protest the shooting of Michael Brown Wednesday, Aug. 20, 2014, in Ferguson, Mo. Brown's shooting in the middle of a street Aug 9, by a Ferguson policeman has sparked a more than week of protests, riots and looting in the St. Louis suburb. (AP Photo/Charlie Riedel)

On Wednesday, a 12-person county grand jury began hearing evidence in the killing of Michael Brown, the black teenager whose death nearly two weeks ago has spawned protests in the city of Ferguson, Mo. and a national debate about race and the use of lethal force by law enforcement.

Many protesters in Ferguson want to see police officer Darren Wilson indicted and convicted for killing Brown. Others are still waiting to see more evidence presented in the case.

Either way, legal experts point to a number of factors that will play into what happens next.

For one, there is copious research showing that a jury's racial composition, can be a factor in the outcome of a case.

A 2007 paper published by the Tufts University Department of Psychology noted that “research on race and legal decision making has provided compelling evidence that race can exert a causal effect on trial outcomes." A 2008 report titled Race and Jury Selection explained that “lawyers often favor jurors who share characteristics with their client because this may increase empathy, making jurors more likely to return a favorable verdict.” And a 2012 study published in the Quarterly Journal of Economics, which analyzed felony jury trial data in Florida between 2004 and 2009, found that merely adding a single black juror to a pool of 27 potential jurors increased conviction rates for white defendants by as much as 11 percentage points. The study concluded that “defendants of each race do relatively better when the jury pool contains more members of their own race.”

Brown was shot in St. Louis County, not St. Louis city. That might sound innocuous, but it's likely to play an important role in the makeup of the jury.

St. Louis County is 70.3 percent white and 23.7 percent black, according to Census figures. Had Brown died just two miles southeast across the county line in St. Louis city, the jurors would be coming from a county where, by contrast, 43.9 percent of the population white and 49.2 percent is black, based on the Census.

The location of the shooting at--2900 Canfield Drive--is less than two miles from the county line.

Ferguson is circled above in red.

And there's another factor to consider: cops are far less likely to be convicted of a crime than an ordinary citizen.

The Cato Institute conducted a 2010 report looking at allegations of police misconduct in the United States from April 2009 to December 2010 involving almost 11,000 law enforcement officers during that time period. Out of that total, only 1,063 officers, or 9.7 percent, were "ultimately convicted of those charges or reduced charges associated with the original allegations." Of the officers who were convicted, 36 percent were sentenced to prison or jail time.

By contrast, in the general population, the conviction rate was 68 percent from 2002 to 2006 (the latest data available from the U.S. Bureau of Justice Statistics at the time when Cato conducted its report). Out of those who were convicted, an average of 70 percent were incarcerated. In the country’s 75 largest counties in 2006, driving-related offences had the highest rate of conviction with 85 percent, followed by murder with 81 percent; the crime with the lowest rate of conviction was assault at 54 percent. Murder convictions had the highest rate of incarceration at 100 percent; among felonies, fraud had the lowest at 55 percent.

"There are biases in the criminal justice system that favor law enforcement in every case," said Peter Joy, a professor at the Washington University School of Law. "It is rare that a police officer gets charged."

By law, officers are allowed to use deadly force in order to apprehend a suspect who has committed or attempted to commit a felony. Assault, as it happens, is a fairly simple felony to accuse someone of—and a fairly difficult one for those accused of it to deny. "If Brown shoved, punched, or even threatened the officer, that would be considered assault," said Anders Walker, a professor of law at St. Louis University. "Even if Brown ran, that's evading arrest, which is a felony, too. So the law is kind of in Darren Wilson's corner."

The Washington Post reported Thursday that according to a family friend, Wilson suffered a fracture to his eye bone in a fight with Brown—although there remains no official confirmation of this injury.

Another important factor in the proceedings is the St. Louis County prosecutor Robert McCulloch, who decided to bring the case to a local grand jury, rather than issue a criminal complaint himself against Wilson. The grand jury must decide whether there is enough evidence to warrant a trial; nine votes out of 12 are required for there to be an indictment.

McCulloch’s personal and professional experience also has drawn attention. McCulloch’s father was a cop who was killed in the line of duty when McCulloch was 12 years old. Opponents question his impartiality based on a case he oversaw in 2000 in which two white police officers shot and killed two black men. The officers, who were working as undercover drug agents, fired at the two men even though they were unarmed. McCulloch did not push for an indictment, nor did a county grand jury end up choosing to indict the two officers.

For his part, McCulloch has pledged to be both thorough and fair in his prosecution. "We will present absolutely everything to this grand jury," he told the radio station 550-KTRS in St. Louis Tuesday morning.

McCulloch will present the grand jury with potential charges—for instance, whether to consider indicting the police officer with manslaughter one, a crime born of negligence, or manslaughter two, which is unintentional but born from a separate unlawful act.

How he presents the evidence and the potential charges will have a significant impact on the outcome of the hearing. If the grand jury opts to indict Wilson, a trial will follow.

At this point, it's not clear what kind of evidence is even available for McCulloch to present.

"I'm not inclined to jump to any particular conclusions," said Joy, the Washington University law professor. "I don't feel like we even have 20 percent of the evidence the jury is going to hear."

The exact circumstances of the shooting are still largely unclear. By some accounts, Brown was shot while surrendering; by others, he was killed while charging at Wilson.

Two separate autopsies--one official from the county and another that was private--show that Brown was shot at least six times. The result of the private autopsy revealed, among other things, that Brown was shot in the top of the head. That bullet was likely the last of half a dozen that hit him, said forensic pathologist Michael Baden, who helped conduct the private autopsy requested by Brown's family. A third autopsy ordered by U.S. Attorney General Eric H. Holder Jr. was completed by U.S. military medical examiners; its results have not been released or reported yet.

"The bullet wound that is seen as the fatal wound in the top of the head could either mean he was on his knees or charging at Daren Wilson," Joy said. Answering that question will be key to proving whether Wilson was assaulted, and therefore justified in using his weapon, or simply out of line, explained Joy.

The fact that so many bullets were fired could also work against Wilson. Technically speaking, the more shots that are fired, the more it can be made to look like a deliberate murder, Walker explained. "Each time someone fires a shot, they have a moment to think about what they're doing," he said. Walker said the defense, however, is capable of arguing that it was a tense situation, and that all of the shots were part of a single action, and therefore a single moment.

"If the grand jury looks at the evidence and says the officer was within his legal authority and decides there isn't sufficient evidence to take this to trial, that's going to be explosive," Walker said.

Regardless of what the county prosecutor and grand jury elect to do, though, there's still potential for the Department of Justice to look at the case separately. "The federal government has to decide whether there was a federal civil rights violation," Joy said. "If Officer Wilson is found not guilty on the state level, he could still be found guilty on the federal level—there's no such thing as double jeopardy here, because they're separate sovereigns."

Amid the unrest in Ferguson, and anticipation around the rest of the country, the nation will have to wait patiently for the case to unfold. "I would anticipate that it will be weeks, not days, before we hear a decision from the grand jury," Sullivan said. By McCulloch's estimate, the process could take months. The prosecutor has said he hopes to present all of the evidence by "the middle of October."