Neighbourhood watch volunteer George Zimmerman was today cleared of all charges in the shooting of Trayvon Martin.
The killing of the unarmed black teenager unleashed furious debate across the US over racial profiling, self-defence and equal justice.
Mr Zimmerman, 29, blinked and barely smiled when the verdict was announced. He could have been convicted of second-degree murder or manslaughter.
But the jury of six women, all but one of them white, reached a verdict of not guilty after they deliberated for more than 15 hours over two days.
After hearing the verdict, Judge Debra Nelson told Mr Zimmerman he was free to go.
Trayvon’s mother and father were not in the Florida courtroom when the verdict was read, but supporters of his family who had gathered outside yelled “No! No!” upon hearing the verdict.
The jurors considered nearly three weeks of often wildly conflicting testimony over who was the aggressor on the rainy night the 17-year-old was shot while walking through the gated townhouse community where he was staying and where Mr Zimmerman lived.
None of the witnesses who were called had a clear view of their encounter.
Defence lawyers said the case was classic self-defence, claiming Trayvon knocked Mr Zimmerman down and was slamming the older man’s head against the concrete sidewalk when Mr Zimmerman fired his gun.
“We’re ecstatic with the results,” defence lawyer Mark O’Mara said after the verdict.
“George Zimmerman was never guilty of anything except protecting himself in self-defence.”
Prosecutors called Mr Zimmerman a liar and portrayed him was a “wannabe cop” vigilante who had grown frustrated by break-ins in his neighbourhood committed primarily by young black men.
Mr Zimmerman assumed Trayvon was up to no good and took the law into his own hands, prosecutors said.
State Attorney Angela Corey said after the verdict that she believed second-degree murder was the appropriate charge because Mr Zimmerman’s mindset “fit the bill of second-degree murder”.
“We charged what we believed we could prove,” she said.
As the verdict drew near, police and city leaders in the Orlando suburb of Sanford and other parts of Florida said they were taking precautions against the possibility of mass protests or unrest in the event of an acquittal.
The Martin family’s lawyer Benjamin Crump acknowledged the disappointment of Trayvon’s supporters, ranking him alongside civil rights heroes Medgar Evers and Emmett Till in the history of the fight for equal justice.
But he urged them not to resort to violence.
“For Trayvon to rest in peace, we must all be peaceful,” he said.
The verdict came a year and a half after civil rights protesters angrily demanded that Mr Zimmerman be prosecuted.
He was not arrested for 44 days after the February 26, 2012, shooting as police in Sanford insisted that Florida’s Stand Your Ground law on self-defence prohibited them from bringing charges.
Florida gives people wide latitude to use deadly force if they fear death or bodily harm.
Demonstrators later protested in three California cities against the acquittal of Zimmerman and officials say they broke windows and vandalised cars in Oakland.
The Oakland police dispatch office said about 100 people protested there and police were dealing with acts of vandalism. The office had no word of any arrests.
Local media reports said some marchers vandalised a police squad car and police formed a line to block the protesters’ path.
The Oakland demonstration followed a raucous but largely peaceful one in San Francisco, which police say ended by 10pm.
City News Service reported that the verdict also sparked protests in Los Angeles, where hundreds of people gathered in a park for what police termed a peaceful vigil.
At one point, a group stopped a passenger train and police worked to persuade them to return to the nearby park.