JENA La.

Martin Luther King III, the oldest son of the famed civil rights leader, urged a crowd Tuesday night to use the ballot box to change a local justice system where six black teenagers face the possibility of decades in prison for attacking a white classmate.

King spoke at what was billed as a town hall meeting to back the teens labeled by supporters as the "Jena Six." He chastised the mostly black audience for failing to vote.

"We have to come together, white folks and black folks, and elect a new district attorney if it's found that he has misappropriated power," King said.

The youths were charged with attempted second-degree murder and conspiracy, sparking outrage in the black community, drawing attention from the American Civil Liberties Union, which is now monitoring the case, and civil rights leaders.

Mychal Bell, who was 16 at the time of the assault, was tried as an adult and convicted of reduced charges of aggravated second-degree battery and conspiracy. He remains in jail, unable to raise a $90,000 bond. He faces up to 22 years in prison when sentenced on Sept. 20.

The other five are awaiting trial on the original charges

District Attorney Reed Walters, who has refused to talk to the media about the case, did not return a call for comment left at his residential number late Tuesday. In the past, he has said he cannot comment because of the pending charges.

King said that if blacks, who make up only 12 percent of the population in LaSalle Parish, voted at 95 percent, they would find the electoral muscle to make changes.

King appeared with the Rev. Al Sharpton, who was making his second appearance in Jena in support of the teenagers. He called the case "a national disgrace."

"Any time you have two levels of justice in any court system, it undermines everything," Sharpton said.