[Langus]

The way I read the Rangiku situation, it could turn out one of two ways. The obvious being that she was an original carrier of the hougyoku and is somehow involved (perhaps even without her knowledge).

The second, and I think more plausible theory, is that she has nothing to do with it whatsoever. Aizen's cronies roughed her up/raped her (her yukata is all spread open etc.) and Gin put two and two together himself when he saw them with Aizen. The two incidents aren't related - just happen to be a coincidence - and from that Gin built up a lifetime of hatred towards Aizen and planned to make him pay.

Given Kubo's past writing style, having it be revealed at some point that Aizen had nothing to do with Rangiku being attacked and furthermore had no knowledge of it could be very plausible.