Klaus has been digging around just about everywhere and has some trained vampires he's paid for (*cough* Minions in the underground compelled to obey him, two of which serve as hired hands to Torchwick, so long as Torchwick's orders don't implicate Klaus in any way).
In keeping a careful balance, anyone human in the Survey Corps interested in a little plot whereupon Klaus compels them (vampire mind magic, literally) to give him intel on a consistent basis for a bit?
Same goes for the Interior! Though he might compel Marie to get the in just so I can villain my way into more things. Seriously, pray for Elijah to come soon.