In GTA Vice City Stories, Diego and Armando are first mentioned by Jerry Martinez in the mission Brawn of the Dead. Jerry tells Victor Vance that the shipment of coke that him and Lance stole belonged to the Mendez brothers.
Eventually, the two are brought the the Mendez Mansion, where Victor tells the brothers stole their shipment of coke, and used some photos of Martinez talking to the cops and a fake license to prove this to the Mendez brothers. Victor and Lance continue to work for the brothers until they decide to take over Victor's businesses and leave him and Lance for dead in an oil burning facility.
Victor and Lance escape from the storage facility and turn to seek protection from Ricardo Diaz, who helps the Vance brothers destroy the Mendez brothers' bonds with a Domestobot. In revenge for the destruction, Armando kidnaps Louise Cassidy-Williams, kills her and injures Lance while Victor makes his way through the mansion. Eventually, Victor confronts Armando, who is weilding a flamethrower and guns him to death.
After Diego hears that his brother was gunned down, he flees to his compound in Downtown, Vice City. Victor then, along with the help of Ricardo Diaz and Phil Cassidy, steal a Hunter attack helicopter from Fort Baxter Airbase and uses it to attack the compound in Downtown, killing both Jerry Martinez and Diego at the compound.
Diego is shown to be more quiet than Armando and only speaks Spanish. Armando is shown to be the one with more control over the organization. Reni Wassulmaier shows that he had a relationship with Diego. They also owned a Domestobot, which Armando destroyed when Victor took control of it and destroyed his bonds.
Armando is based off of Scarface's Alejandro Sosa, as Armando shows a resemblance to him in personality and appearance. Diego resembles Giorgio Moroder. The men's names play on Argentinean soccer star, Diego Armando Maradona. It's unknown why the names were a play on him.
- Louise Cassidy-Williams- Kidnapped and killed by Armando to lure Victor and Lance into his trap.
Diego isn't shown to have commited any crimes.
- In Diego's artwork, he is shown to be holding a Beretta M12 sub-machine gun, a weapon that isn't featured in the game.
- In the mission "Light My Pyre," if the player uses a flamethrower on Armando, he won't take any damage. This may be a possible glitch in the game.