New York once had the highest crime rates in the world, the tried a heavy police presence, but that did not work. They tried heavy prison sentences but that did not work. What did work was a clean up of the areas, removal of grafiti, replace broken windows, a good and through clean up of the city. Seems people who live in cleaner areas build a better moral attitude. You can read full story here at the open university blog.
Extract :Twenty years ago most criminologists and sociologists would have doubted that a metropolis could reduce this kind of crime by so much. Although the scale of New York Citys success is now well known and documented, most people may not realize that the city’s experience showed many of modern America’s dominant assumptions concerning crime to be flat wrong, including that lowering crime requires first tackling poverty, unemployment and drug use and that it requires throwing many people in jail or moving minorities out of city centers.

Instead New York made giant strides toward solving its crime problem without major changes in its racial and ethnic profile; it did so without lowering poverty and unemployment more than other cities; and it did so without either winning its war on drugs or participating in the mass incarceration that has taken place throughout the rest of the nation.