I'll go a ahead and say that the biggest found cluster consisted of over 200 accounts.
Now imagine someone comes to you with plausible data that indicate such clusters ? What would you have done ?
I'm pretty sure noone would have said "Well we said we wouldn't do another investigation. So no, let em have it".

Regarding the question of whom to contact - Just contact me. Prefferably only with questions but sure if you need to blow of some steam go ahead.