To smoke out a nest of traitors, give them just enough info so they know you're not clueless.
Let that start working on their sleep for a few restless nights.
Wait for them to start scurrying a bit as a result, then feed them a little more to fuel the fear.
The more scurrying, the more distrust amongst the nest, and the paranoia keeps feeding itself.
A few more tidbits - some revoked passports, some financial subpeonas - and one or more will race to give up the others to save their own wretched hide.
And that's when the house of cards comes tumbling down.
In the words of Mr. Miyagi: Patience, grasshoppa