The correlation between intellectual deficiency and violent crime is worldwide, and not specific to any one race. Here is a chart compiled in a Cambridge study of the English population.
The school systems have good census information of the students in the under 80 IQ group, and provide some level of guidance until graduation. Then it's sink or swim for this group. The school systems should be required to report at risk subjects to the mental health system, and laws should be enacted to allow them to provide similar or even more rigorous support for at risk adults. Otherwise, a lot of them won't get that support until they have a probation officer.