Its a very interesting subject, and depends how far down you want to go before you are satisfied with an answer.

Both victimization and offending rates for murder were 3-4x the rate for blacks than whites in 1980 for example. Why was that? Could it be factors like systematic racism, redlining, bundling a lot of poor people into housing projects, brain drain in cities (due to redlining post-integration)?

The result of "tough on crime" has been incarceration rates exploding. They just throw anyone in jail. 5% of black adults are in jail.

https://en.wikipedia.org/wiki/United_States_incarceration_ra...

You would think that since the crime rates are down, the incarceration rate would be going down - how can incarceration rates go up as crime goes down? Technology and standard of living increases for the poorest has probably helped crime. The mass incarcerations just help for-profit prisons.