Colombian conflict dialogue, but President Barco sent an ultimatum to the guerrillas and demanded that they immediately disarm or face military retaliation. Regional guerrilla and Army skirmishes created a situation where each violation of the ceasefire rendered it null in each location, until it was rendered practically nonexistent. By 1990, at least 2,500 members of the FARC-founded Patriotic Union had been murdered, according to historian Daniel Pecáut, leading up to that year's assassination of presidential candidate Bernardo Jaramillo Ossa. The Colombian government initially blamed drug lord Pablo Escobar for the murder but journalist Steven Dudley argues that many in the UP pointed
Pablo Escobar of Córdoba and Urabá. "Los Pepes" carried out a bloody campaign, fueled by vengeance, in which more than 300 of Escobar's associates, his lawyer and relatives were slain, and a large amount of the Medellín cartel's property was destroyed. Members of the Search Bloc, and Colombian and United States intelligence agencies, in their efforts to find Escobar, either colluded with "Los Pepes" or moonlighted as both Search Bloc and "Los Pepes" simultaneously. This coordination was allegedly conducted mainly through the sharing of intelligence to allow "Los Pepes" to bring down Escobar and his few remaining allies, but there are reports