The US is a strange case, though. You have an enormous prison population as a proportion of your general population. Money becomes an issue when such a large percentage of the population is incarcerated, but when you have a more reasonable justice system (and a social security net which removes a large percentage of the impetus for crime...
The US' enormous prison population is largely a result of the details of the way the social security net was implemented. (Here we call it the "social safety net", and the subset in question "welfare programs", because "Social Security" is reserved for a particular government-operated retirement benefit.)
The primary culprit is LBJ's "Great Society" push, which created and/or increased welfare programs, especially those related to child support. Starting in that period they included rules that ended the benefits if an adult male was living in the house with, or married to, a mother raising children. (It was presumed that the male in question was, or was acting as, husband/lover and father, and should be providing the support for the family.) The rules also reduced benefits if the mother got a job. The reduction was dollar-for-dollar (or worse), with no allowance for costs of working (such as transport, uniforms, or babysitting).
Though blacks were only about half the welfare receiving population, they were a far smaller portion of the general population - especially as the benefits were selectively extended to them in the wake of the Civil Rights movement and the related riots. So the effects of these programs was greater on the black population than the rest of the citizenry.
The results of these rules were, for the poor blacks, the destruction of the (formerly notoriously strong) black family - removing any productive male role model from the household of any welfare recipient- and the conversion of welfare programs from a temporary emergency measure to a way of life. Children of long-term welfare families tended to see living off welfare as how resources are obtained and have no experience with alternatives - resulting in their going on welfare (and recruiting others) for generation after generation. Welfare mothers tend to have more children than those in families supporting themselves. Others are recruited to this lifestyle, and once in it find themselves trapped. Thus the fraction of single-mother families with no male role model rises. At this point about 72% of US (non-Hispanic) blacks are born to unmarried mothers, versus 30% for (non-Hispanic) whites and about half that for asians.
One of the problems with single-mother families is that single mother is usually unable to socialize an adolescent male child. (The differences in violent crime rates between ethnic groups in the US completely disappear if you adjust for the illegitimacy rate.)
So the social safety net seems to be the entire cause of the rise in violent crime. Like government in general, these social programs seem to be a disease masquerading as its own cure.