Not only rumour, no; Bella was not able to break her occlumency shield entirely, but there were one or two slips. Apparently it was not only Pomona, but Aurora as well -- Bella reported a brief thought of Pomona regretting that she'd gotten Aurora involved in all this. And, from what happened afterward, one must presume Poppy and David were both involved as well. (I cannot make that much make sense. Poppy and Pomona were inseparable, of course, and Auri was close to them both, but David was never particularly part of their circle.)

We'll need to question everyone left. And talk to the students, as well. This is going to be miserable to clean up from.