OAKLAND, Calif. (AP) - The trial of a white former San Francisco Bay Area transit officer charged in the killing of an unarmed black man will be moved to Los Angeles County because of extensive media coverage and other possible distractions to trial participants, a judge ruled Thursday.

The decision by Alameda County Superior Court Judge Morris Jacobson comes a month after he decided the murder trial of Johannes Mehserle would be moved out of that area.

State court officials recommended Los Angeles and San Diego counties to the judge as possible sites for a trial.

Mehserle, 27, is charged with fatally shooting Oscar Grant, 22, at a Bay Area Rapid Transit station in Oakland on New Year's Day. The incident was video-recorded by several bystanders, shown across the Internet and subsequently used as evidence in a preliminary hearing last spring.

"This is the most important decision in this case, other than the verdict," John Burris, the attorney representing Grant's family, said after Thursday's ruling. "If the case went to San Diego County, Mehserle would have walked."

"L.A. County has a lot more experience dealing in cases with African American men being killed by police," he said. "They can understand those issues rightly or wrongly, up or down."

Mehserle has pleaded not guilty in the case. Jacobson said that Los Angeles County court officials may not be ready to handle the case for at least six months, even a year.

Jacobson apparently had to weigh costs for Alameda County by comparing possible trial costs in Los Angeles and San Diego counties. The judge said San Diego County court officials told him that their courthouse was not prepared for a high-profile case and would have to make significant security adjustments and provide a judge at a cost to Alameda County.

Los Angeles County said it would be able to provide its own judge.

Mehserle's attorney, Michael Rains argued Thursday that he preferred San Diego County because it has enough courtroom space and with Mehserle's right to a speedy trial, one could begin as early as January.

Rains also argued that if the trial is held in Los Angeles County, there could be a "boiling cauldron" similar to the violent aftermath in the 1992 Rodney King case.

Rains also said there has been more media coverage in Los Angeles about the case compared to San Diego.

"It is possible that this case ignites that boiling cauldron," Rains said.

Rains argued for a change of venue, citing a survey of nearly 400 potential jurors. It found nearly 97 percent knew details about the case, and nearly half believe Mehserle is guilty or probably guilty.

Prosecutor David Stein argued on Thursday that Los Angeles County has the capability and the security needed for such a highly charged case. He also said the odds of getting more African Americans on a jury is greater in Los Angeles County than in San Diego County.

A diverse jury will bring more "legitimacy" to Alameda County residents, no matter the final outcome, he added.

"When the verdict is ultimately rendered, the people of Alameda County must feel like their interests have been served," Stein said. "The interest of justice makes it clear that it should be in Los Angeles."

According to 2008 Census figures, 14 percent of Alameda County's 1.5 million residents are African-American, compared with 9 percent of the 9.9 million residents in Los Angeles County and 5 percent of 3 million residents in San Diego County.

Grant's mother, Wanda Johnson, said she was overjoyed with the judge's decision. She said she planned to attend the trial.

"I want to ensure that justice is served, and my family believes that in Los Angeles County we can get a better pool of jurors and a more favorable decision there than San Diego," she said.

Jacobson said he will ask state Supreme Court Chief Justice Ronald George to assign a justice to handle the trial. The judge set another hearing for Dec. 15.