Thanks for the suggestion, actually I am focusing on Ciudad Juarez, Mexico, and I am using Medellin, Colombia as a case study. For sure I'll share my findings.
I can think of a friend of mine in Brazil who is familiar with this topic: Carla Cipolla (you can find her through Researchgate). You might also want to look at the cases of CEPTED.
You might take a look at Jared Diamond's "The World Until Yesterday" and Steven Pinker's "The Better Angels of our Nature: Why Violence has Declined." Both are top scientists and genius award winners. While the take somewhat different approaches, both credit aspects of urbanization with our reduction in violence.
I choose Medellin due to the outstanding transformation it has been through; it was the most dangerous city in the world in the 90's and after adopting a social urbanism perspective in their urban agenda they managed to gradually decrease violence.
Ciudad Juárez is my hometown and it lived the same violent past 6 years ago.
Therefore I will like to explore how through initiatives that foster social inclusion the decrease of violence is achieved.