Wesker then appeared alongside William Birkin in "Resident Evil Zero", a prequel to the original game where it is revealed that he attended the Umbrella Executive Training School as a prospective executive, and later in "Resident Evil 4" as a conspirator manipulating events from behind the scenes, where he would issue orders to Ada Wong. He is also unlockable in "The Mercenaries" scenario. He is also the protagonist of ' and a playable character in several of the game's scenarios, expanding upon events alluded to in early games, as well as his involvement in Umbrella's downfall after the events of "Code: Veronica" and his development in "Resident Evil 4". In the end he kills Sergei Vladimir, a loyal Umbrella executive. Wesker also very briefly appears in ', as he at one point is seen by Jack Krauser. He also gave Javier a sample of the virus within Steve Burnside.