Updated

Jurors weighing the fate of a Minnesota police officer who killed a black motorist last July are headed into their fifth day of deliberations Friday.

Officer Jeronimo Yanez is charged with manslaughter in the death of Philando Castile. Yanez shot Castile during a traffic stop in a St. Paul suburb after Castile informed the officer he was carrying a gun.

On Wednesday, the apparently deadlocked jury was summoned to court by the judge and told to keep deliberating. Thursday's deliberations passed quietly, with no sudden hearings or requests from the jury to review evidence.

Some key information about the case:

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THE FACTS

Yanez pulled over Castile, a 32-year-old elementary school cafeteria worker, for a faulty taillight. On squad-car video of the traffic stop, Castile tells Yanez, "Sir, I have to tell you, I do have a firearm on me." Yanez tells Castile not to reach for it, then fires seven rapid shots into the car, hitting Castile five times.

The shooting gained attention immediately because Castile's girlfriend, Diamond Reynolds, livestreamed its gruesome aftermath on Facebook. Reynolds was in the car with her then-4-year-old daughter.

Yanez, who is Latino, is charged with second-degree manslaughter, punishable by up to 10 years in prison, though sentencing guidelines suggest around four years is more likely. He also faces two lesser counts of endangering Reynolds and her daughter for firing his gun into the car near them.

Central questions of the case are whether Yanez, 29, saw Castile's gun, and whether he acted reasonably. Castile had a permit to carry the firearm, and witnesses testified that it was in the pocket of his shorts when paramedics pulled him from the vehicle.

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WAITING FOR A VERDICT

All 12 jurors must reach a unanimous decision. To convict Yanez on the manslaughter charge, they must find beyond a reasonable doubt that Yanez acted with culpable negligence, which the judge described as gross negligence with an element of recklessness.

While Yanez's squad-car video shows the shooting from a distance, there's no video showing exactly what happened in the car or what Yanez saw. So jurors are weighing conflicting evidence, including Yanez's testimony that Castile had his hand on his gun, Reynolds' testimony that Castile did not reach for the firearm, and the views of outside experts who made plausible cases for why Yanez did or did not act reasonably.

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KEY EVIDENCE FOR PROSECUTORS

Yanez made statements to a supervisor after the shooting and to investigators the next day that, on the surface, seem to indicate he never saw Castile's gun. The statements to the supervisor were captured on Yanez's squad-car video. That audio was played multiple times at trial, as was the video of the shooting.

Prosecutors argued that other evidence shows Castile could not have had his hand on the gun when he was shot. They noted that one of Yanez's bullets grazed Castile's trigger finger and that there was no bullet hole in his shorts nor any damage to the weapon.

Prosecutors also argued Yanez had other reasonable options, including ordering Castile to put his hands on the steering wheel.

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KEY EVIDENCE FOR THE DEFENSE

Yanez testified that Castile was pulling out his gun and ignore commands to stop. "I was scared for my life. I thought I was going to die," he said.

He also said he reacted the way he was trained to do. Asked about statements he made to investigators that seemed to indicate he didn't see the gun, he claimed he just meant he didn't see it at first.

Defense attorneys also argued that Castile was stoned on marijuana and that it contributed to his failure to follow the officer's instructions.

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WHAT IF THE JURY CAN'T REACH A UNANIMOUS VERDICT?

The judge would declare a mistrial, and prosecutors would then decide whether to retry the case.

Castile's mother, Valerie Castile, has said she plans a lawsuit. It's common for civil suits to proceed no matter the outcome of criminal cases, as the burden of proof in civil court is less than in a criminal case.

A federal investigation into whether Yanez intentionally violated Castile's civil rights is also possible, but unlikely. Federal civil rights investigations have a higher legal standard and an accident, bad judgment or simple negligence is not enough to bring federal charges. Federal authorities have said they were monitoring the state's investigation, and a federal prosecutor helped with the state's case.

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ARE MISTRIALS UNUSUAL IN SUCH CASES?

Not really. Philip Stinson, a criminologist at Ohio's Bowling Green State University who tracks fatal police shootings, compiled data that shows almost 40 percent of cases in which officers were charged with murder or manslaughter since 2005 have ended in mistrials or acquittals when officers testified they feared for their life.

One such case involved Ray Tensing, a former University of Cincinnati police officer. Prosecutors are retrying him in the killing of Sam DuBose, an unarmed, black motorist, during a traffic stop near the campus in July 2015.

In Charlotte, North Carolina, prosecutors decided against retrying Randall Kerrick, a white officer who was charged with voluntary manslaughter for shooting Jonathan Ferrell, an unarmed, black 24-year-old. Kerrick shot Ferrell 10 times after Ferrell crashed his car in a suburban neighborhood and banged on a neighbor's door looking for help.