If its dioxin then it can't be a pro assassination attempt. Dioxin is poor choice for poison cause in liquid form it is hard to get (and thus a tip off it's a wet work), it needs a lot to kill and is detectable.
Why poison him and let him live and have so much evidence? In Serbia they drove people off the roads, shot them. Like the pro-NATO Drinic (?sp) who was elected in the same type of "revolution", took power, handed everything to the West, got empty promises, got pissed off, threatened to divolge everything and was quickly gunned down....hmmm.