Kazren

Kazren was a Dessev Breen. Trop

In 2382, Kazren infiltrated the Starfleet Utopia Planitia Fleet Yards to steal the quantum slipstream drive technology. Starfleet did not know that the Dessev were aligned with the Breen Confederacy and Kazren had security access to the facility. 

Kazren would later help the Typhon Pact to attempt to steal Dominion technology.