The demographics are entirely irrelevant to this discussion and I really wish people would stop bringing it up because it's the same type of racist thinking that causes police to disproportionately target African American males. Rampant recidivism, a vengeful justice system, and an entirely ineffectual mental health treatment are the real problems - not the density, skin color, or socioeconomics of urban populations. Crime in those environments is driven by a nearly inescapable cycle of political and economic disenfranchisement starting in childhood and ending in a prison cell.

It is a massive self-reinforcing feedback loop. If we had even an ounce of the empathy and rational approach to public safety that the Nordic countries had, we wouldn't be having this discussion and that feedback loop would have been broken a century ago.