Kerry said Sunday that hat blood and hair samples taken from medics at the scene of the alleged attack point to the nerve agent sarin. The samples reached U.S. hands "through an appropriate chain of custody, from east Damascus, from first responders," he said.
But David Kay, the former head of the U.S. weapons hunt in Iraq, said the "shadowing effect" of that war makes the U.N. inspectors' jobs more difficult.
"Remember, these results will be analyzed and re-analyzed around the world," said Kay, the former U.N. weapons inspector who ultimately determined Iraq had dismantled the chemical, nuclear and biological weapons programs used to justify the American-led invasion in 2003. "So as an inspector, you want to get it right rather than necessarily get it quick"
Kay told CNN the question has been settled for the Obama administration "and for many Americans, including myself. But that's not enough, because of Iraq."