Illegal Cocaine Markets and Violence in Colombia

Using different measures for the extent of coca cultivation as independent variables to be instrumented, we find that a 10% increase in the value of coca cultivation in a municipality increases homicides by about 1.25%, forced displacement by about 3%, attacks by insurgent groups by about 2%, and incidents with land mines by about 1% (p. 39).

That is from this paper by Daniel Mejia & Pascual Restrepo.