While your statement "While I agree that many a white murdered blacks with impunity" may have been a summation of the world in 1900 or 1950 it's not a very good summation of the world we live in.
I did a research paper on this one time, I believe that most criminals prey on those in their own community and the crossover is about 20 % for blacks and 20% whites committing crimes outside of their own community. I will look up the figures again to be sure.