In some places violent crimes are overwhelmingly committed by this or that minority -- especially violent crimes of a certain type. Lots of places, for example, have some ethnically-colored mafias.
Another case is poorer immigrant minorities committing more crimes than the baseline population (because of their poorer upbringing, lack of opportunities, alienation from the host society, because some things are culturally OK in their old culture but crimes in their new one, etc).
Another case is poorer immigrant minorities committing more crimes than the baseline population (because of their poorer upbringing, lack of opportunities, alienation from the host society, because some things are culturally OK in their old culture but crimes in their new one, etc).