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
Right-wing paramilitarism in Colombia the Calí Cartel, dissidents within the Medellín Cartel, and the MAS worked together to create a new paramilitary organization known as "Perseguidos Por Pablo Escobar" ("People Persecuted by Pablo Escobar", PEPES) with the purpose of tracking down and killing Pablo Escobar and his associates. The organization was led by Fidel Castaño. The Calí Cartel provided $50 million to pay for weapons, informants, and assassins, with the hopes that they could wipe out their primary rival in the cocaine business. Members of both Colombian and U.S. government agencies (including the DEA, CIA and State Department) provided intelligence to the PEPES. Pablo