Some countries that are "more socialist" than the average have a very low murder rate - others don't do as well, America is possibly the least-socialist "first world" country on the list and its murder rate (comparatively) is through the roof - whether this is a "direct-link" is very difficult to say.The homicide rate charts that andyb linked to are indeed interesting, and everything just screams that it's poverty that's associated with murder. Poverty and social instability.
I don't think that there is a statistician in the world that would not correlate poverty with crime - but that is a long stretch to suggest that simply handing money out to "poor people" will reduce crime. Statisticians will tell you that the poorest will still exist, and some people will still commit crime - therefore there is no end to crime and poverty until everyone has the same wealth - this is a horrible situation called socialism (others might have other names for it, but most of those are political).
I for one, don't like socialism for the basic reasons, (that some people hold to be true) as it simply means that lazy people gain from people who work hard, the opposite should be true. Hard work should reward, and laziness should deprive - these are the rough but fair terms that nature hands out.
However, I do truly believe that there should be "some" socialist bodies that everyone pays for at the same rate regardless of usage, the NHS is that very example. Without it we would be as fat as Americans, and as short lived. The NHS is probably the largest and best run (although we constantly complain about it) single organization on earth, and the last time I saw some numbers, it was about the 8th largest employer on the planet (excluding army's) and remember that this IS a socialist concept.