Caballero began reporting for the Bogotá newspaper La Republica at the age of 16.[3] As a female journalist working in a culture that valued machismo, she has said that she was initially given poorer quality assignments, but overcame this obstacle by investigating "key issues" on her own time and becoming a "happy workaholic".[3]
In 1997, she was granted a rare interview with Carlos Castaño, leader of one of Colombia's right-wing paramilitary groups, the Peasant Self-Defense Forces of Córdoba and Urabá. To meet Castaño, Caballero was forced to ride on horseback for eight hours through mountainous terrain, injuring her back severely enough that she later required surgery for a compressed nerve.[3] In the interview, Castaño revealed for the first time that he was ready for peace talks.[4]
In 1999, Caballero received repeated death threats on her home answering machine; in addition, a security officer from her building warned her that a man was waiting near her apartment with a gun.[3] At the invitation of Harvard Dean Joseph Nye, she left Colombia that day, moving to Cambridge, Massachusetts.[4]
The Inter American Press Association awarded Caballero its Human Rights Award in 1990.[2] In November 1998, she was also awarded the International Press Freedom Award of the Committee to Protect Journalists,[5] "an annual recognition of courageous journalism".[6] CPJ Board Chairman Gene Roberts praised Cabellero and the other recipients as "courageous journalists who faced jail, physical harm and even death, simply for doing their work".[5]