David Kay — American Scientist

David A. Kay is a weapons expert, political commentator, and senior fellow at the Potomac Institute for Policy Studies. He is best known for his time as United Nations Chief Weapons Inspector following the first Gulf War and for leading of the Iraq Survey Group's search for weapons of mass destruction following the 2003 invasion of Iraq. Upon presentation of the Group's finding that there had been significant errors in pre-war intelligence concerning Iraq's weapons programs, Kay resigned. The ensuing controversy served as impetus for the formation of the Iraq Intelligence Commission... (wikipedia)

But the most important thing about that story, which is not often told, is that as a result after the Cuban missile crisis, immediate steps were taken to correct our inability to collect on the movement of nuclear material out of the Soviet Union to other places.
I've seen looting around the world and thought I knew the best looters in the world. The Iraqis excel at that.
The result is - document destruction - we're really not going to be able to prove beyond a truth the negatives and some of the positive conclusions that we're going to come to. There will be always unresolved ambiguity here.
Both of us are known for probably at times regrettable streak of independence.
The Germans certainly - the intelligence service believed that there were WMD. It turns out that we were all wrong, probably in my judgment, and that is most disturbing.