How did race play a role in the Hinton case?

Kelly Arena of CNN reported that Anthony Ray Hinton had spent 21 years on Death Row for committing two murders during robberies. The case raises several questions regarding the fairness in which the death penalty is administered. How did race play a role in the Hinton case? What have studies shown with regard to cases involving minorities? Are there any counter-arguments? In light of the possibility that the death penalty is unfairly administered, should it still be used? Explain.