Prior to Tommy Vercetti's takeover of Vice City, the gang was the dominant drug cartel in Vice City, with Ricardo's aggressive interest in staying on top of the drug smuggling business a defining factor. He is seen requesting the theft of the fastest speed boat in the city for smuggling activities, and killing those who attempt to cut into his profits, even though it only comprises a small percentage. In addition, Diaz's gang is believed to have botched Tommy's initial drug deal with the Vance brothers (consisting of Lance and Victor) forcing Tommy to leave behind (and lose) both the money and narcotic merchandise as he fled the scene.
Tommy Vercetti was given the opportunity to work for Ricardo, while Lance Vance infiltrated the gang under a different name. As Tommy continued to work for Ricardo and planned for a takeover of Ricardo's empire, Lance attempted the overthrow prematurely, failing to kill Ricardo and resulting in his capture and torture by the gang, before Tommy rushed to the rescue. This event forced the two to raid the Diaz Mansion and kill Ricardo before Ricardo "takes them out", killing many of Diaz's men on the way. The killing of Ricardo effectively ended the Diaz Cartel as Ricardo's mansion and all of his assets were seized by the Vercettis and there were no longer any Diaz gang members seen anywhere in the Vice City's storyline (apart from in rampage).