Sorry about the ambiguous title, but I want to prevent spoilers. Read no further if you haven't read through at least The Fires of Heaven in Robert Jordan's Wheel of Time series.
At the end of the 5th book of The Wheel of Time, The Fires of Heaven, Asmodean is killed by an unknown figure right after a shock of recognition.
At what point in the series do we find out who the killer is, and at what point in the series should we have gathered enough clues to figure it out on our own?
Note that I'm not looking for the identity of the killer (if that's even known yet). If you know who it is, please use spoiler text.