Juan Diego Díaz , better known as La Quica, was a sicario in the Medellín Cartel. NARCOS
One of La Quica's first tasks was the assassination of German Zapata; while killing him, he also killed a DEA Agent, Kevin Brady. Quica was arrested for these murders, but was able to make bail and returned to Colombia unpunished (Descenso).
In Colombia, he becomes one of the most prominent sicarios for Pablo Escobar. He's involved in the murders of all possible collaborators of DEA. He is in a personal competition with other sicario, Poison, for having the highest number of murders.
La Quica finds several young boys who are recruited for Pablo's army, and he chooses the boy who explodes a bomb in a plane, killing more than 100 people, in the attempt of killing the president of Colombia.
Later, La Quica recruits Limon, a taxi driver in Medellin, who helps Pablo move around the city. One of the prostitutes working with Limon calls the police and La Quica is almost captured. In revenge, he kills all the prostitutes and tries to kill Maritza, a friend of Limon. Limon and Quica search for her, but Limon tries and succeeds to protect her at the same time.
Quica is one of the last loyal men to Pablo, even though he´s afraid, mostly because he knows that they are defeated. He´s betrayed by Blackie, and tries to escape, killing other of Escobar´s men, but is finally captured by the police.
Quica is interrogated by the DEA and accepts to help them, giving the location of Escobar´s last soldiers and calling Pablo, but Pablo knows that he´s with police and avoids being captured or killed that night.