"Actually, it kind of does add up," Derevko said slowly. "Hertz had this lab running. He wasn't too careful with it. It wasn't really legal- wasn't documented, anyway, no one expected it to be here. Then this guy who's got some idea of the Government messing with his head- and yeah, it's not real. If it was real, the CIA wouldn't have let it pass down to us. They're a lot of things, but a global conspiracy with fingers everywhere who are simultaneously stupid enough to let this go to the fucking Mulder and Skully division, they are not..." The scarred agent's lips pursed.
"Maybe he overhears this guy. Maybe he just caught a glimpse. Anyway, it tips him over the edge in his delusions. He goes apeshit. Starts killing. Only snaps out of it when he runs out of space in the wall... douses the bodies in caustic chemicals to destroy them, maybe."