Brewer, 32, was the second of three men to be tried and convicted in the case, reviving memories of the old South of racist lynchings and the Ku Klux Klan. John King, an ex-prison mate of Brewer's, was found guilty of Mr Byrd's murder in February and sentenced to death by lethal injection. Shawn Berry, the third accused, goes on trial next month.
During his trial, Brewer insisted that he took no part in the killing, blaming King and Berry. He said that King got into a fight with Mr Byrd, and that Berry had intervened. He said that Berry had slit Mr Byrd's throat and then chained his body to the back of his truck.
Brewer, sometimes sobbing, testified last week that he was with King and Berry when Mr Byrd, 49, was chained to the bumper of Berry's pick- up and dragged for three miles along a rutted logging road.
But according to Brewer he climbed inside the truck cab, smoked a cigarette and did not realise Berry had chained Mr Byrd to the back of the truck until they began driving.
"Clearly there is a pattern of deceit," Jasper County District Attorney Guy James Gray said in his closing statement before the case went to the jury. "He crafted his story to try to imply James Byrd was dead before they started dragging him."
Prosecutors argued that the three men together kidnapped Mr Byrd after a deal to buy body-building drugs went wrong and then dragged him along a country track until his head was severed. Brewer and King had become acquainted in prison in the mid-Nineties where they belonged to the same white supremacist gang.
While the savagery and racist nature of the crime horrified America, some regarded the speedy arrests and relatively uncontroversial trials as a sign of progress. In the past, a predominantly white town might have closed ranks and declined either to hand over or to convict the culprits.
Prosecutors said they believe the three men killed Mr Byrd to promote their fledgling white supremacist organisation - the Confederate Knights of America - and initiate Berry into the group.