Rittenhouse, 18, faces life in prison if he is convicted of the most serious charge against him.
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He was 17 when he shot two men to death and wounded a third during a tumultuous night of protests against racial injustice in the summer of 2020.
Rittenhouse said he went to Kenosha from his home in Antioch, Illinois, to protect property from rioters in the days after a Black man, Jacob Blake, was shot by a white Kenosha police officer. Rittenhouse, a former police youth cadet, is white, as were those he shot.
SEE ALSO | Jacob Blake, Kyle Rittenhouse shooting timeline
Eighteen jurors have been hearing the case; the 12 who will decide Rittenhouse's fate and the six who will be designated alternates were determined by the drawing of names from a lottery drum.
The judge had Rittenhouse pull the numbers of the six alternates from the drum just after 9 a.m., and the remaining 12, seven women and five men, went to deliberate. The six alternates, three men and three women, will stand by separately in the Kenosha courthouse.
WATCH: Kyle Rittenhouse pulls numbers of alternate jurors
The jury is now considering the five remaining criminal charges against Rittenhouse. Two charges, one about curfew and another about illegal gun possession, have already been dropped or dismissed.
"The key question is whether he acted recklessly, Rittenhouse did, and whether he acted with utter disregard for human life," said ABC7 Legal Analyst Gil Soffer. "And, of course, underlying that charge and every other one is was he acting in self-defense?"
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Jurors are reviewing hours of livestreamed video that showed Rittenhouse shooting and killing two men and badly injuring a third, from countless angles.
"There's a near certainty that this jury is looking at those videos and looking at them again and again," Soffer said. "It's the most important kind of evidence. In this case, each side made an enormous deal of it. So, I have to believe those jurors are looking at those videos, talking to one another about what they're seeing, what it proves, what it doesn't."
They'll first decide if Rittenhouse fired in self-defense, or if the armed teenager provoked Joseph Rosenbaum before fatally shooting him. If jurors believe Rittenhouse was reasonable to fire, trying to save his own life, he could be acquitted of recklessly endangering Richie McGinnis, an online videographer who was a few feet away when Rittenhouse killed Rosenbaum.
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"It was clear to me that something with the weapon was about to happen and I didn't want to be on the wrong side of that," McGinnis testified during the trial.
Jurors now have more options to convict Rittenhouse after Judge Schroeder allowed them to consider less severe charges related to the killing of Anthony Huber and the attempted homicide charge for Gaige Grosskreutz, the armed medic who Rittenhouse shot in the arm. But those additional options could prolong the closed door deliberations.
"I never cease to be amazed at how thoughtful jurors are when they're told this is the law. These are your instructions. These are the facts that you're considering. You're to apply the law to the facts, and they take that very seriously," Soffer said.
Jurors are under strict instructions not to say anything about the case until all 12 of them are back in juror quarters Wednesday morning. Rittenhouse's defense team said if he is convicted on any of the charges, he's likely to be taken into custody immediately.
On Monday, the prosecution and defense each made one last attempt to sway the jury during closing arguments.
"This case is not a game. You don't play fast and loose with my client's life," lead defense attorney Mark Richards said.
WATCH | Defense attorneys make closing arguments
During the trial, defense experts testified that in a span of less than three minutes, Rittenhouse fired his semi-automatic weapon eight times at four people.
During his closing Monday, Richards even invoked the police officer who shot Jacob Blake, prompting the protests
"Other people in this community have shot somebody seven times, and it's been found to be OK," he said. "My client did it four times in 3/4 of a second to protect his life from Mr. Rosenbaum."
In the state's dramatic last stand, lead prosecutor Thomas Binger painted Rittenhouse as a coward who falsely portrayed himself as a medic.
"This is someone who has no remorse, no regard for life, only cares about himself," Binger said.
WATCH | Prosecutors make closing arguments
Rittenhouse fled in fear, provoking the crowd, who, Binger said, tried to stop the teen, shooting and killing again as he ran.
"Consider whether or not it's reasonable for a criminal to shoot his way out of a crime scene. In this case the crowd was right. The crowd knew the defendant just shot someone," Binger said.
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Jurors are no longer considering charging Rittenhouse with illegally carrying a weapon.
The judge dropped that charge Monday after arguments about the barrel-length of the gun.
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The Associated Press contributed to this report.