The Drug Enforcement Agency or DEA is a government agency that appears in Grand Theft Auto: Vice City Stories.
The agents wears the same uniform as the FBI, but without the hat and glasses. And they drive different vehicles.
They appear in The Exchange for the deal that was made by Ricardo Diaz, one of agents appear in The Mugshot Longshot to get Jerry Martinez into the witness protection program. And they were metioned in Turn On, Tune In, Bug Out, when they bugged Lance's apartment in order to collect some evidence against the Vance brothers to have them arrested. They are monitoring the handover of the drug deals.