So I've read all the books, but i only have ToM at the moment, and I've seen all these posts about Asmodean's killer being obvious, but i can't find anyone actually mentioning who his killer was. (sorry if i've overlooked this on another thread, i went through quite a few but couldn't find it :/ )

Prior to TOM, it's intuitively obvious to the most casual observer. TOM material is forbidden on this board for now, but there are several threads on the TOM spoiler board about any new developments in identifying Asmodean's killer. This, for instance. Or my post here.