Board Thread:Questions and Answers/@comment-24826159-20140425195736/@comment-8986886-20140425220731

Alaba wrote: just wondering as i would feel quite bad if they didnt.

If they bothered to question Don Kanonji, Tatsuki, and the others witnesses, about what happened, they should've been able to figure it out. Also, when Rangiku first confronted Gin and Aizen, Gin was fine. Rangiku was then rendered unconscious from the effects of Hakufuku, and after she woke up, she eventually found Aizen, in a new Hogyoku form, standing next to a mortally wounded Gin. She must have put two and two together. Ichigo arrived at the same time, so he should have come to the same conclusion. Though, the circumstances revolving Gin's death were never discussed in the manga, or in the anime.