JNN 10.07.10 Hundreds of protesters have taken to streets in the US city of Oakland to oppose a court ruling on a white police officer’s killing of an unarmed African-American.

The protest turned violent on Thursday night, with the demonstrators throwing rocks and bottles at police. At least 50 people have been arrested for fighting with the police.

Former Bay Area Rapid Transit officer Johannes Mehserle was found guilty of “involuntary manslaughter” of Oscar J. Grant III, on New Year’s Day of 2009.

The conviction usually carries a maximum four-year sentence. But some in Oakland expected a tougher penalty for the former police officer, on the grounds that he committed hate crime.

“This is not an involuntary manslaughter case,” said John Burris an attorney for the Grant family. “This is a true compromise verdict that does not truly and accurately reflect the facts, and we are extraordinarily disappointed at that,” Burris said, according to AFP.

“My son was murdered. He was murdered. He was murdered. My son was murdered,” said Grant’s mother, Wanda Johnson, CNN reported. “The system has let us down, but God will never ever let us down.”

The killing of the 22-year-old African-American took place at an Oakland train station.

The protesters say the verdict is racially-motivated.

They say the defendant should have been convicted of at least second-degree murder.

“We do believe that this was a murder case, a second-degree murder, and we are surprised” by the decision, Burris said.