The 18-year-old from Antioch is accused of killing Joseph Rosenbaum and Anthony Huber, and shooting and trying to kill a third man, Gaige Grosskreutz, during protests last year in Kenosha. Rittenhouse claims he fired his semi-automatic gun in self-defense.
Opening statements started just after 9 a.m.
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Rittenhouse has pleaded not guilty.
Before arguments even began, the court's by-the-book Judge Bruce Schroeder insisted the three men can't be referred to as "victims."
Judge allows men Kyle Rittenhouse shot to be called 'rioters,' 'looters' but not 'victims'
Out of the gate prosecutors swung hard, insisting Rittenhouse killed the two men and tried to kill the third on purpose.
"There were hundreds of people on the street that night, experiencing the same chaos," said Assistant District Attorney Thomas Binger. "The same loud noises, the same gunfire, the same tear gas, the same hostile confrontation with people who believe the opposite of them. And yet, out of these hundreds of people only one person killed anyone that night."
WATCH: Prosecutors begin opening statement in Kyle Rittenhouse trial Part 1
WATCH: Prosecutors begin opening statement in Kyle Rittenhouse trial Part 2
Rittenhouse alternatively yawned and sat alert in court as his defense team laid out their case that the teen was in fact the victim that night. Showing photos and videos frame-by-frame, the defense said Rittenhouse shot Rosenbaum as the man chased him, and killed Huber when he swung a skateboard at his head and tried to wrestle away his gun.
"Kyle Rittenhouse protected himself, protected his firearm so it couldn't be taken, used against him or other people. Mr. Rosenbaum made threats to kill, and the other individuals who didn't see that shooting attacked him in the street like an animal," said defense attorney Mark Richards. "Ladies and gentlemen, that's what the evidence will show."
In video from that night after the first shooting, played by the defense, someone in the crowd yells, "He f------ shot him! Get him!!" and the crowd chases after Rittenhouse.
That's when the defense said Huber swung his skateboard as a weapon, and said Grosskreutz was armed with a handgun.
Dominick Black bought the gun for Rittenhouse. Under oath Black, who was also armed that night, described first seeing Rittenhouse after the fatal shootings.
"He was freaking out, sweating a lot. Pale," Black recalled. "He said he had to do it, it was self-defense."
"Did he ever say someone was trying to attack him with any sort of weapon?" prosecutors asked.
"No," Black answered.
There were no rallies so far outside the courthouse Tuesday, but Rittenhouse's family walked in ahead of opening statements.
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A jury was selected for the trial in just one day Monday, despite the worldwide attention the case has received.
According to a pool reporter in the courtroom, there is only one person of color on the jury. An exact racial breakdown of the jury has not been available.
In August of 2020, Rittenhouse was 17 when he traveled just across the Wisconsin border during protests that broke out after the police shooting of Jacob Blake.
During the protest, which was sometimes violent, Rittenhouse shot three protesters, killing two of them. His attorneys claim he acted in self-defense and that he came to Kenosha to protect local businesses. They will argue he feared for his life as a mob of protesters chased him down a street, swinging a skateboard and trying to wrestle away his gun.
Rittenhouse, now 18, faces multiple charges, including two counts of first-degree homicide, attempted homicide and recklessly endangering safety for firing his weapon near others.
If convicted of the most serious charges, he could face life in prison.
What to expect in Kyle Rittenhouse trial
The case has attracted worldwide attention, and he has become something of an icon to gun rights activists and self-proclaimed militias, crowdfunding more than $2 million in online donations for his legal defense.
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The trial is expected to last two to three weeks.