Too bad she's so slow at catching the culprit. If she was a bit brighter, she would've dealt with the individual responsible for all of this a long, long time ago.
I mean, why didn't she even suspect the messenger? He's not a part of the household, so he'd be the one to really suspect in the first place, since he'd be easier to bribe. But she is a dum-dum, so can't expect her to understand anything.