BOGOTA, Colombia (AP) — A former mayor allied with presidential candidate Abelardo de La Espriella was shot dead in Colombia ‘s heartland, local authorities said Saturday. One of his aides was also killed. The killings of Rogers Devia and his staffer Eder Cardona was the latest incident of political violence in a region under dispute by two groups labeled as terrorists by the U.S. government and a third group — a splinter of the once dominant guerrilla Revolutionary Armed Forces of Colombia, or