(Corrects percentage of Jackson's black population, paragraph 7)
By Therese Apel
JACKSON, Miss., July 16 (Reuters) - Four white Mississippi residents pleaded not guilty on Wednesday to federal hate crime charges stemming from an attack on a black man run over by a truck and killed, in a case that has already yielded six convictions.
The 2011 killing of James Craig Anderson, 47, sparked outrage for its heinous nature, particularly since it took place in Mississippi, a state that has struggled to overcome a long history of racism.
"This was specifically a hate crime," said Anderson family attorney Winston Thompson. "He was killed because he was black," he added.
John Louis Blalack, 20, Sarah Adelia Graves, 21, Robert Henry Rice, 23, and Shelbie Brooke Richards, 20, each pleaded not guilty in federal court in Jackson to numerous hate crime and conspiracy charges.
All but Rice are accused of being present when Anderson was ambushed in a motel parking lot in June 2011, when several people jumped out of their vehicles and punched him in the face.
When Anderson fell, one of the group struck him with a pickup truck and shouted: "White power," authorities have said.
Jackson, which is about 79 percent black, is the state capital and Mississippi's largest city.
In addition to the other charges, Blalack and Rice were charged with the use of a firearm in commission of a crime.
The defendants face a Sept. 15 court date. They could face sentences of up to life imprisonment if convicted.
The driver of the pickup truck, Deryl Paul Dedmon, pleaded guilty to state charges involving Anderson's death and was sentenced to two life terms.
Dedmon is among six young white men who pleaded guilty to federal hate crimes charges in connection with the case.
Joseph Dominick, Dylan Wade Butler, John Aaron Rice, William Kirk Montgomery and Jonathan Kyle Gaskamp, all now in their early 20s, are awaiting sentences of up to life in prison.
"We are still seeking justice for my brother's death," Anderson's sister, Barbara Anderson Young said. "We're still holding strong to our faith every day and we know that God is still in charge."
Attorneys for the four defendants charged on Wednesday declined to comment on the case. (Wriitng by Jonathan Kaminsky; Editing by David Adams and Peter Cooney)