According to Risen, the CIA's Russian contact/messenger noticed flaws in the schematics for the TBA 480 high-voltage block during his briefing for the operation in San Francisco.[1] After recognizing the errors, the Russian asked nearby agents about said discrepancies and his inquiry was ignored. Some members of the CIA were unsettled by the Russian's observations, but Operation Merlin progressed nevertheless. Shortly before flying to Vienna for the delivery, the Russian was handed a sealed envelope, containing the blueprints for the "firing set", and was ordered to not open the envelope.