Here is a link to an interview with John Reuwer in which he discusses his work in Harrisburg to try to minimize the number of murders.  John did the recent workshop at our meetinhouse on Non-violent communication.  He is part of Harrisburg Monthly Meeting.  .He is trying to apply the Cure of Violence model to homicides.  Cure of Violence takes a public health approach to the problem.  It trains and employs formerly incarcerated members of the community to patrol and monitor the neighborhoods most prone to violence.  

http://www.witf.org/smart-talk/2015/12/smart-talk-can-new-project-cure-harrisburg-violence-best-way-to-heat-your-home.php

Here is the Cure Violence home page: http://cureviolence.org/

The library also has the documentary The Interrupters, which is about the CureViolence program.