Rewatched Wanted last night and noticed an odd bit. While chasing Cross, Wesley quickly turns around and shoots someone behind him. This turns out to be The Exterminator--the guy with who liked to feed the rat explosives and use them as bombs. When The Repairman gets there, he is shocked to find The Exterminator, implying The Exterminator has no business being there.
The Exterminator mentions multiple times that Wesley's father had though about using thousands of rats in this way. Later, when Wesley finds Cross's plans to attack the Textile Mill, it seems to involve using such rats.
So, why was The Exterminator there? Specifically, was he working with Cross as an inside agent?