Guess. Bad health? Lack of good education? Poverty?
Poverty is the closest one. It is actually relative poverty. That is, if you measure the ratio of rich people to poor people in a given area, you get relative poverty levels and this is measured by the Gini Coefficient. The Gini coefficient correlates with crime rates with a ratio of 0.9, out of 1. That means 0.9 is almost bulletproof.
You can find some more info here. You can just scroll down to the parts highlighted in green and “crime”.