After the chaotic 1986 Docks Deal, Tommy Vercetti, through Ken Rosenberg's contact, began working for Colonel Cortez. Tommy would do errands for Cortez, while he assured Tommy to find information regarding the key culprits behind the attack at the docks.
|“||I'm ashamed to admit that one of the causes of our mutual problem appears to have been the loose tongue of a man I used to trust. I've been carrying Gonzalez for years, but now his incompetence reaches new heights! It is only right that you kill Gonzalez...||”|
–Colonel Cortez about Gonzalez
In the mission Treacherous Swine, Cortez informed Tommy that his old-time ally, Gonzalez, disclosed the information about the Deal, thus making it easy for the attackers to ambush the deal. Later on in the game, Cortez finds out that Ricardo Diaz was the mastermind behind the 1986 Docks Deal.
|“||Although I'm starting to think that Diaz was responsible for our unfortunate loss. One does not wave accusations at a man like Diaz||”|
–Cortez on Diaz
During the storyline, Cortez never discloses his source of information, though it can be Kent Paul. It is, however, unlikely since Tommy was well aware of every possible leak Kent knew.
It is theorized that Cortez tipped flawed information to Tommy Vercetti, only to eliminate his friend turned rivals, such as Ricardo Diaz and Gonzalez, due to the growing tension between the two and Cortez. It is plausible however never confirmed as Tommy took Cortez's word on the information.
Since Rockstar never added a reference about the information being false, the theories regarding the conspiracy are regarded as unlikely. However, Cortez' actual source of information still remains a mystery.