Petrov and Nickerson had dropped a number of hints to Victor and other Salemites that John might be the presumed-dead Roman Brady, a police captain and former ISA agent of high value due to his abilities and knowledge of various highly classified subjects (and who was actually being held captive by Stefano at the time). Indeed, using the brainwashing techniques learned from Petrov, Stefano had implanted enough facts from Roman's life into John's subconscious that he was able to convince everyone, including John himself, that he was in fact Roman Brady, for a period of over five years. Stefano did this to exact revenge on Roman's family, with whom it was later revealed Stefano's father had a longstanding vendetta.