In a racially charged case, white ex-police officer Johannes Mehserle, whose killing of a 22-year old unarmed black man on a train platform was caught on video from multiple cameras, was released from prison after 11 months.
He was released at 12:01 a.m., a spokesman for the Los Angeles County Sheriff's Department told CNN.
Mehserle, 29, was released early because he earned good time credit while in jail. He was convicted of involuntary manslaughter and sentenced to a 2-year minimum term.
The killing of Oscar Grant, 22, triggered outrage in Oakland, California after the killing took place on New Year's day.
Five videos during the trial showed Mehserle pulled his gun and shot Grant in the back as another officer knelt on Grant.
Mehserle testified that he had mistaken his pistol for his Taser. Police were attempting to subdue Grant after a fight on a Bay Area Rapid Transit train.
A judge in the case who sentenced Mehserle believed that there had been a weapons confusion due to poor training of its officers and near-riot conditions at the station.
Mehserle's muscle memory took over in this moment of great danger and stress, the judge said at the time. No reasonable trier of fact could have concluded that Mehserle intentionally fired his gun.
Mehserle had also been charged with second-degree murder and voluntary manslaughter.
Mehserle was tried in Los Angeles because of extensive publicity about the case in the Bay Area.