A jury acquitted Kyle Rittenhouse on charges that he murdered two men and attempted to kill a third with his semi-automatic rifle during protests in Wisconsin in 2020, determining that the teenager acted in self-defence.
A 12-member jury found Mr Rittenhouse, 18, not guilty on two counts of homicide, one count of attempted homicide and two counts of recklessly endangering safety during street protests marred by arson, rioting and looting on 25 August, 2020 in the city of Kenosha.
His trial polarised the US, highlighting gaping divisions in US society around contentious issues like gun rights.
Mr Rittenhouse shot and killed Joseph Rosenbaum, 36, and Anthony Huber, 26, and fired a bullet that injured Gaige Grosskreutz, 28.
The defence argued that Mr Rittenhouse had been repeatedly attacked and had shot the men in fear for his life.
They said he was a civic-minded teenager who had been in Kenosha to protect private property after several nights of unrest in the city south of Milwaukee.
The unrest followed the police shooting of a Black man named Jacob Blake, who was left paralyzed from the waist down.
The prosecution portrayed Mr Rittenhouse as a reckless vigilante who provoked the violent encounters and showed no remorse for the men he shot with his AR-15-style rifle.
Protests against racism and police brutality turned violent in many US cities after the police killing George Floyd in Minneapolis three months before the Kenosha shootings.
The Rittenhouse verdict ended the highest-profile US civilian self-defence case since a man named George Zimmerman was acquitted in the fatal shooting of Trayvon Martin, an unarmed Black teenager, in Florida in 2013.
With so much of that night in Kenosha caught on cellphone and surveillance video, few basic facts were in dispute.
Thetrial instead focused on whether Mr Rittenhouse acted reasonably to prevent "imminent death or great bodily harm," the requirement for using deadly force under Wisconsin law.
The prosecution, led by Kenosha County Assistant District Attorney Thomas Binger, sought to paint Mr Rittenhouse as the aggressor and noted he was the only one to kill anyone that night.
Mr Rittenhouse's gun was loaded with 30 rounds of full metal jacket bullets, which are designed to penetrate their target.
The jury saw a series of graphic videos, including the moments after Mr Rittenhouse fired four rounds into Mr Rosenbaum, who lay motionless, bleeding and groaning. Other video showed Mr Grosskreutz screaming, with blood gushing from his arm.
Mr Rittenhouse testified in his own defence last Wednesday in the trial's most dramatic moment - a risky decision by his lawyers given his youth and the prospect of tough prosecution cross-examination.
Mr Rittenhouse broke down sobbing at one point but emphasised that he fired upon the men only after being attacked.
"I did what I had to do to stop the person who was attacking me," he said.
Mr Rittenhouse testified that he shot Mr Huber after he had struck him with a skateboard and pulled on his weapon.
He said hefired on Mr Grosskreutz after the man pointed the pistol he was carrying at the teenager - an assertion Mr Grosskreutz acknowledged under questioning from the defence.
Mr Rittenhouse testified that he shot Mr Rosenbaum after the man chased him and grabbed his gun.
Biden warns against 'violence' after protest verdict
President Joe Biden warned against "violence" in the wake of the acquittal.
He acknowledged that the verdict left him and "many Americans feeling angry and concerned," but said the "jury has spoken" and must be respected.
"I urge everyone to express their views peacefully, consistent with the rule of law. Violence and destruction of property have no place in our democracy," he said, noting that his team had been in touch with Wisconsin authorities "to prepare for any outcome."
Shannon Watts, founder of gun control group Moms Demand Action, was among those denouncing the not guilty verdict.
"That a teenager could travel across state lines to a protest he had nothing to do with; shoot three people, killing two; and face no criminal consequences is a miscarriage of justice and an indictment of our criminal justice system," Ms Watts said.
New York Mayor Bill de Blasio called the verdict "disgusting."
"It sends a horrible message to this country," De Blasio said. "To call this a miscarriage of justice is an understatement."
The NAACP, the African-American civil rights group, said the verdict is a "travesty and fails to deliver justice on behalf of those who lost their lives."
"A system that legitimises vigilante murder is deeply broken," tweeted Wisconsin Representative Gwen Moore, a Democrat.
Republican politicians welcomed the not guilty finding.
"Justice has been served," said Wisconsin Senator Ron Johnson. "I hope everyone can accept the verdict, remain peaceful, and let the community of Kenosha heal and rebuild."
Wisconsin Governor Tony Evers has put 500 members of the state National Guard on standby in the event of trouble.
