So, what did THEY use to do to a black man after he raped a white girl? It's always fun to go back in time.
They would have been reluctant to hang a black slave if he was valuable
Probably mutilate him and sell him off
For raping a white woman
It would also matter if the white woman was Gentry or not
Inciting a slave rebellion was the only thing which death as punishment was certain for a valuable strong adult male fieldhand or artisan skilled slave
Some were worth as much as 40-50,000 in todays money
You didnt destroy or harm that irrevocably for nothing