Interesting, that would lead us to akiyama's parents' divorce, but I think it would add unnecessary mystery element to something as trivial as a divorce, considering that the robber(who Is implied to have some dirty(not "that" way) connection with takeda) mentioned "X". I'd put my guess on the woodpeckers association... Btw, that was some mind blowing trick!! Nice idea! ^^ that basically put us closer to calling akiyama the murderer, but since he also died, someone else(like saegusa) must've dealt with him(my guess would be with the intention of hiding the meaning of the X) and to finish the deal, they are planning to put the blame on kansuke, who was already akiyama's scapegoat, so that they can finally hide the secret of the X(looking at kuroda's suspicious behavior in ch 916, he's probably in on it)..............and then gosho will throw a bomb at us at the end by revealing that the woodpeckers are fraction of or connected to the BO, with RUM being their leader...