Weeks into the invasion of Iraq, as the Bush administration panicked over its failure to find any weapons of mass destruction, the Iraq Survey Group was hastily assembled.
It was headed by the controversial and outspoken CIA adviser David Kay and later by Charles Duelfer, who told journalists he was convinced of a link between Saddam Hussein and the 11 September attacks.
The ISG, manned by 1,200 intelligence officers and weapons experts mostly from the US and Britain, spent six months searching for WMD and issued its interim report a year ago.
The best it could come up with was that Saddam Hussein's regime was engaged in "WMD-related programme activities" but had no actual chemical, biological or nuclear weapons.
But this proved a great embarrassment for Washington and London. The British Government, in particular, placed heavy emphasis on intelligence indicating Iraq had WMD as a primary justification for the invasion.
Then in January Mr Kay, resigned, saying that he believed WMD would not be found in Iraq. He told the Senate Armed Services Committee: "We were all wrong and that is most disturbing."
Mr Duelfer has said the chances of finding WMD in Iraq are "close to nil".
The ISG continued the work of UN inspectors, led by Hans Blix and Mohamed ElBaradei, sent by the UN Security Council to search for illegal weapons before the conflict.
After Saddam's capture, Mr Blix played down suggestions that he would reveal the whereabouts of illegal weapons stockpiles. "I doubt he will reveal any WMD, because I think both the UN inspectors and the American inspectors have come to the conclusion that there aren't any. He might be able to reveal when they were done away with. I am inclined to think it was early in 1991 or 1992."