This seems to be a problem at a lot of campuses and has been for some time now. That's part of the reason that so many former campus security departments have been converted to fully accredited police departments with bluelights, guns and body armor. IMO the source of the problem is that many schools are surrounded by a ring of low cost rental property (much of which was created by "white flight" in the 50s and 60s), which appeals to both students and lower income non-students. Where ever you have a lower-income community there will be the typical groups that prey on low income people: gangs; street criminals such as corner drug dealers and prostitutes; illegal gambling enterprises; etc. Other than gentrification of these areas, which often puts a squeeze on affordable student housing, I'm not sure that there is an answer.
