Got to thinking about the extent of this unimpressive outcome thus far…
Problem: how to flush out the guilty assuming you know absolutely nothing.
How:
Warn of impending justice and name members of a group exposing deep knowledge of serious wrongdoing. Persist at message and watch who reacts and goes on strong offense and feigns outrage.
You now find out who’s guilty, but not exactly to what degree and without any real knowledge or evidence of specific wrongdoing. However, now you have the target time to investigate.
Occasionally disclose nearing in on closing the loop and monitor reaction of target for additional clues.
Targets that begin to show signs of relaxation are guilty, but likely have learned that they are being targeted and without damaging evidence.