Curve Ball is an Iraqi defector named Rafid Ahmed Alwan, who arrived at a German refugee center in 1999. To bolster his asylum case and increase his importance, he told officials he was a star chemical engineer who had been in charge of a facility at Djerf al Nadaf that was making mobile biological weapons.
He eventually wound up in the care of German intelligence officials to whom he continued to spin his tale of biological weapons. His plan succeeded partially because he had worked briefly at the plant outside Baghdad and his descriptions of it were mostly accurate. He embellished his account by saying 12 workers had been killed by biological agents in an accident at the plant.
More than a hundred summaries of his debriefings were sent to the CIA, which then became a pillar - along with the now-disproved Iraqi quest for uranium for nuclear weapons - for the U.S. decision to bomb and then invade Iraq. The CIA-director George Tenet gave Alwan’s information to Secretary of State Colin Powell to use at the U.N. in his speech justifying military action against Iraq.
Tenet gave the information to Powell despite a letter - a copy of which 60 Minutes obtained - addressed to him by the head of German intelligence stating that Alwan appeared to be believable, but there was no evidence to verify his story.
Obviously he was lying and apparently some in the CIA caught him at it and were ignored, which I think is the more important story.
Of course this being 60 Minutes they have to trot out the yellowcake uranium chestnut again so I once again have to point to the SSCI report which found that Joe Wilson's report tended to support the contention that Iraq was trying to acquire uranium.
There is also a new book out about this episode:
Iraq, War, CIA, Curveball, 60 Minutes, WMD