He started his professional career in the economic sector, first as Assistant Manager of CitiBank in Colombia, and then as a consultant for Arthur Young & Co. López Caballero was ambassador to France, from where he returned to serve president Gaviria as his minister for agriculture.
López Caballero's effectiveness and his lack of interest for the spotlight is what led president Pastrana to appoint him as one of the government's negotiators during the peace process with the FARC communist guerrillas.
During the peace negotiations he earned the respect and the trust of the top members of the guerrilla group, mainly due to his clarity, his understanding of the country and its politics, and more importantly, to the sincerity and openness with which López Caballero faced the multiple discussions [1].
Earning this recognition from the FARC was seen as quite remarkable by some commentators given that López Caballero was clearly a representative of the political, social and economic elite of the country [2].
López Caballero was appointed ambassador to the United Kingdom by president Uribe where he was instrumental in strengthening commercial links and in gaining support for an offensive against the guerrillas, paramilitaries and organized crime [3].