A US TV network has revealed the name of "Curveball" - an Iraqi man whose information was central to the US government's argument to invade Iraq.
The US cited Mr Alwan's bio-weapon claims in its war argument
The CBS show 60 Minutes identifies him as Iraqi defector Rafid Ahmed Alwan.
The programme says he arrived in a German refugee centre in 1999 where he lied to win asylum and was not the chemical expert he said he was.
His claims of mobile bio-weapons labs in Saddam Hussein's Iraq were backed until well after the 2003 invasion.
'Playing the system'
The CBS 60 Minutes programme airs on Sunday but material released on its web site says Curveball was "not only a liar, but also a thief and a poor student instead of the chemical engineering whiz he claimed to be".
It also says it assumes Mr Alwan is now living in Germany under a different name.
The programme says he claimed to be a star chemical engineer at a plant that made mobile biological weapons in Djerf al-Nadaf.
However, its investigation showed he received only low marks in chemical engineering at university and was the subject of an arrest warrant for alleged theft from a TV production company he worked for in Baghdad.
The programme also includes footage of his wedding in 1993 in the Iraqi capital.
It quotes former CIA senior official Tyler Drumheller as saying: "It was a guy trying to get his green card essentially, in Germany, and playing the system for what it was worth."
German intelligence agents warned the US in a letter that there was no way to verify Mr Alwan's claims.
Colin Powell used the information in a speech to the UN
However, his information was used in a speech by then Secretary of State Colin Powell at the UN to back military action in Iraq.
The 60 Minutes report says the information was passed on by then CIA director George Tenet, who denies ever seeing the German intelligence letter.
The programme says Mr Alwan's story unravelled once CIA agents finally confronted him with evidence contradicting his claims.
Back in November 2005, Col Lawrence Wilkerson, the chief of staff to Mr Powell, told the BBC's Carolyn Quinn he was aware the Germans had said that they had told the CIA of the unreliability.
"And then you begin to speculate, you begin to wonder was this intelligence spun; was it politicised; was it cherry-picked; did in fact the American people get fooled?," Col Wilkerson said.
A presidential intelligence commission into the matter found that Curveball was a liar and an alcoholic.