Good points all.
Yes, the Intuition skill does say "detect lie". Sorry, I was essentially giving my "houserule" on that.Lots of the time, in simple situations I let it work pretty much as that but still giving more general description, "the halfling insists he doesn't have it anymore- he seems nervous and keeps glancing at the boxes in corner" (probably the thing you're looking for, possible the skaven he was just speaking to before you came in and hiding over there....)
I do find the scripts for the 3 suspects in Part 3 a bit lacking on some points such as Black Cowl and have been annotating them - and having fun doing it. By this point, they have all heard of this figure due to the PC's actions in Averheim. In my game it's understood by all that the BC is behind mutant bandits stealing blackpowder and mutant gold wizards doing strange things with effigy from South Lands - almost certainly thus a Chaos cultist etc.
In my game, all 3 were part of the "conspiracy" to "prolong the situation" in Averheim as part of being politically avaunt-garde or exploiting it or hoping to see a better candidate emerge than same-old/same-old nobles who have been disastrous for Averand etc.
My conspiracy is fracturing at this point between "wealthy liberal reforms who want money ahem talent I meant, to replace the dead hand of nobility and let us do more research, reform courts - and really don't want a typical Leitdorf or Alptraum in charge, willing to get a dirty to do it." and the "inner core of BC loyalists, villains to the core"
Going with what you say, Baerfaust and Kaufman might both have contacted, through their lieutenants Schaffer and Weiss, to "go along" with the BC's move to control criminal world" as an expedient way of keeping it from getting too wild - both "shocked to learn there were mutants and cultists involved". Neither ever met the BC, it was their lieutenant who did in both cases (because the real BC has not one but three lieutenants).
Having made my BC choice, I'm revising Part III a fair bit. Also the trip from Middenheim as Adele will be along (a week in a coach with a witch hunter - who says travel is boring).