This is a special report on Drug related violence in Mexico from the University of San Diego.
Drug Violence in Mexico
This is a PDF and it is like a booklet. Lots of statistics.
See this wikipedia page for cities with highest murder rates, Mexico (9/50) runs only behind Brazil (16/50)for having the most cities on this short list (#50) Also this one on crime in Mexico.
Another study, Mexico has the highest crime rate in the world