A white former transport policeman was convicted of involuntary manslaughter for shooting an unarmed black man on a station platform in an encounter that sparked days of rioting in Oakland, California.
Prosecutors had wanted Johannes Mehserle convicted of murdering 22-year-old Oscar Grant, who was shot as he lay face-down. Mehserle said he meant to stun Mr Grant with a Taser, but drew his handgun by mistake.
Mr Grant’s mother, Wanda, later condemned the verdict outside the court in the city.
“My son was murdered! He was murdered! He was murdered!” she said.
Cephus Johnson, Mr Grant’s uncle, said the family had been “slapped in the face by a system that has denied us a right to true justice”.
“We truly do not blame the jury, but we blame the system,” he added.
On the east side of San Francisco Bay, police in riot gear were deployed on the streets of Oakland.
A crowd near Oakland City Hall moaned and cursed when they heard the verdict. A dozen people gathered in a semi-circle to pray.
“It’s not real, it’s not real. Where’s the justice? He was killed in cold blood,” said Amber Royal, 23, of Oakland.
California governor Arnold Schwarzenegger issued a statement urging people to remain calm and not resort to violence.
The jury had a choice between murder and lesser charges of voluntary and involuntary manslaughter. It jury found that Mehserle did not mean to kill Mr Grant, but that his behaviour was so negligent that it was criminal.
Involuntary manslaughter carries a sentence of two to four years. The next hearing was set for August 6.
The jury included eight women and four men. None listed their race as black. Seven said they were white, three were Latino, and one was Asian-Pacific. One declined to state their race. They left the court under tight security.
At least five bystanders videotaped the New Year’s Day 2009 incident in what was among the most racially polarising cases in California since four Los Angeles officers were acquitted in 1992 in the beating of Rodney King.
The case was a rare instance in which a police officer stood trial for an on-duty killing and that was captured on video from so many different angles.
The verdict followed a three-week trial in which Mehserle, 28, said that he struggled with Mr Grant and saw him digging in his pocket as officers responded to reports of a fight at a station.
Fearing Mr Grant may have a weapon, Mehserle said he decided to shock him with his Taser, but drew his .40-calibre handgun instead.
Alameda County deputy district attorney David Stein said in his closing argument that Mehserle let his emotions get the better of him and intended to shoot Grant with the handgun without justification.
Mehserle pleaded not guilty to murder and resigned from the Bay Area Rapid Transit agency after the shooting.
Fallout from the shooting was swift in Oakland after the videos were shown on television and the internet. The shooting and the nearly two weeks it took to arrest Mehserle sent the city into a tailspin of violence as downtown businesses were damaged, cars were set ablaze and clashes erupted between protesters and police.
Mr Grant had recently been released from jail after being sentenced to 16 months for a gun possession charge filed after he ran from police and was subdued by an officer with a stun gun.
Mr Grant has become a martyr of sorts in a city where more than a third of residents are black. His omnipresent image on buildings and storefront windows arguably rivals that of murdered home-town rapper Tupac Shakur.
Mr Grant’s family and friends filed multi-million-dollar lawsuits against the transit agency. Only the mother of Grant’s daughter has reached a settlement.