Claudia Messina was an American DEA attaché sent to Colombia to oversee the capture of drug lord Pablo Escobar.
A tough but fair leader, she demanded discipline and perfection from all her workers, going as far as to almost firing Steve Murphy after the latter had a drunken fit until his partner Javier Pena stepped in defending him explaining that Murphy was drinking because he was having marriage problems with his wife Connie who wants to go back to Miami after Steve gets kidnaped by the Cali cartel but Murphy didn't want to leave until he brings down Medellín cartel and Escobar is dead or imprisoned. After hearing Pena's plea, Messina decides to give Murphy a chance to clean himself up and try to figure out a way to make things work at home with Connie or she'll send him back to Miami to which he was able to do so and was back in professional shape.
She crossed swords with the CIA as they prevented the DEA from going after Escobar's rivals in Cali. The CIA wanted the Los Pepes and Cali cartel to stay in power to prevent various left-wing organizations from taking over the void left by the Medellín cartel after Escobar's downfall. She later discovered that Peña was collaborating with Los Pepes by sharing classified intelligence. In order to prevent this from causing a scandal, she agreed to allow Peña to allow distraught Los Pepes co-leader Judy Moncada to act as an informant for the DEA after she was removed from the organization. However, CIA Station Chief Bill Stechner forces Moncada to be an informant for the CIA instead and ordered her to blame Peña and the DEA for the creation of Los Pepes. As a result, Messina is transferred back to the United States along with Pena after being declared Persona Non Grata.