An investigation determined that plastic explosives were used to destroy the plane. Drug kingpin Pablo Escobar, of the Medellín drug cartel, planned the bombing in the lead-up to the 1990 elections, hoping the bomb plot would kill presidential candidate César Gaviria Trujillo. One account states that two unidentified men dressed in suits who worked for Escobar carried the bomb on board. The men sat in seats 18A and 18K, located above the main fuel tank. At the last moment, one of the men left the aircraft, while his partner stayed on board and was killed in the bombing. Gaviria was not on the aircraft, despite Escobar's expectations, and went on to become President of Colombia. Two Americans were among the dead, prompting the Bush Administration to begin Intelligence Support Activity operations to find Escobar.