I wouldn't buy the "Assad did this" story. First, the media again jumped to this conclusion way too quickly based on basically hearsay. Second, even if the government in Syria still had stockpiles of chemical weapons (which they disposed of under the scrutiny of international community years ago, by the way), why use these weapons when they know all well that the world is watching? Assad is not a fool, he has an upper hand in the conflict and a superior firepower in terms of conventional weapons.  Why jeopardize his position? On the other hand, the "rebels" are losing and this incident (as well as the resulting media narrative) benefits them. How convenient is it to have the government "gas their own people" at this particular time? This story is definitely fishy, and it doesn't add up. I won't have high hopes of finding the real perpetrators, though. The ability to objectively investigate something in a war-zone like Syria is usually very limited.