User blog comment:God of nothing/Shiba clan logic/@comment-1332195-20130501062344

Which happened first, Isshin's desertion or Kaien's death? Not been able to find anything concrete either way. Knowing who was in charge when (and by extension, if one succeeded the other) may help determine which if either was the straw that broke the camel's back or just a contributing factor.

I said back when Isshin was revealed as 10th's captain that this could have something to do with the clan's fall; we now know the manner of how he left (without Aizen being a spotlight stealing drama queen for once. Was that part of the plan? ,:\ ), and desertion is possibly the lowest of the low in military eyes, so I'd wager this was the coup de grace for the Shibas.

As for cover-ups, I'd say that's more Central 46's shtick; I'd think Yama'd be more 'I want him found and I want him dead!'.