(Ariga's prequel to Resident Evil)
Vickers was a member of the Special Tactics and Rescue Service, a law enforcement unit in Raccoon City.
In 1998, the S.T.A.R.S. Bravo Team was sent to investigate a mansion where a series of murders were occuring near. When they disappeared, Captain Wesker sent in Alpha Team along with Chambers; Frost and Vickers to investigate.
Vickers is neither part of Alpha or Bravo team in this universe; instead, he; Chambers and Frost form a third, unnamed unit.