Jaramillo started working primarily in the Urabá Antioquia region until 1987 when he assumed the presidency of the Patriotic Union Party (UP) after the assassination of Jaime Pardo.

Being a high school student and in the midst of a protest, he met the legendary trade union leader Rubén Darío Castaño whom he considered his political mentor and shortly after, joined the ranks of the Colombian Communist Youth (JUCO) where he reached positions of leadership.

[1] He specifically blamed president Barco of ignoring the evidence of the collaboration between drug cartels and Colombia's military to create and fund the paramilitary forces responsible for the assassinations.

Two days before his assassination, Carlos Lemos, who was the Minister of Government at the time, dismissed Jaramillo's accusations and in turn suggested that UP was the political branch of FARC.

Jaramillo responded by saying that such accusation was both unfair and baseless, and that it meant essentially a death sentence for him and UP members, which proved true just two days later.

[2][3] He was in Bogotá's Puente Aéreo terminal of El Dorado airport with his wife Mariela Barragan and several bodyguards provided to him by DAS.

[4] A young paramilitary hitman, named Andrés Arturo Gutiérrez Maya, waited for him while he and his wife were in front of a pharmacy, then pulled out a Mini Ingram 380 machine gun and fired on the candidate.

[9][10][11] An anonymous call to a radio station in Medellin attributed the murder to the paramilitary organization of Fidel Castaño, who apparently had inherited the criminal structure of Gonzalo Rodriguez Gacha, who had been killed months before.

[1] On February 11, 2010, Alberto Romero, an ex director of the DAS (Colombian Security Service), was charged as being linked to the murder, together with Carlos Castaño, the chief of the AUC (paramilitary forces).