South African authorities say a police captain faces murder charges for allegedly helping four farmers beat two suspected thieves to death in a case that ignited racial tension in a rural town.

Police said Thursday that Capt. Hendrick Jacobus Prinsloo, who is white, was called to the scene of the beating in the town of Parys in the Free State province. They say Prinsloo, instead of rescuing the two black men being beaten, joined the white farmers in the assault.

When the farmers appeared in court on suspicion of murder in January, police had to keep apart groups of white farmers and black protesters outside the courthouse.

The four accused farmers say the two men beaten to death had tried to rob one of them with a gun.