I remember that also. It was Mansoor Ijaz on Fox News who when questioned one-on-one by Brit Hume said he had "irrefutable evidence" of a convoy of WMD being driven into Syria. Brit stopped him and said, "now let me get this straight so there is no confusion, you are stating that sources will come forward with evidence of this WMD convoy going to Syria. Mansoor dramatically looked directly in the camera and said "irrefutable evidence". Haven't seen Mansoor since.
Good example ... another one that comes to mind is TWA Flt. 800.
if we could locate Al Douri (in Syria), we might know the answer to that.