I. Lewis Libby, known to the world as "Scooter", has been described as the archetype of a senior Bush Administration official.

A taciturn veteran of the State Department and the Pentagon, Mr Libby, 55, has been called "a neo-con's neo-con" and "the man behind the guy behind the guy", a nod to his important role in the affairs of Dick Cheney, the Vice President.

Taught at Yale by Paul Wolfowitz, the current head of the World Bank and an architect of neo-conservative foreign policy, Mr Libby began his career in public service at the State Department in 1981, where he worked as a policy adviser with a special focus on East Asia and the Pacific.

Under George Bush Sr, Mr Libby rejoined Mr Wolfowitz at the Pentagon and worked under Mr Cheney, then Secretary of Defence, for the first time.

At the Department of Defence, Mr Libby helped develop a confrontational post-Cold War foreign policy that became discredited during the Clinton years, but has become the guiding principle of the Bush Administration since the September 11 attacks.

According to The Washington Post, Mr Libby, like Mr Cheney, "greatly admires the work of Victor Davis Hanson, a classicist and military historian who posits that warfare is an inevitable part of civilization, evil is a basic condition of humanity, and tyrants must be confronted by the harshest possible means."

As well as serving as Mr Cheney's Chief of Staff, Mr Libby is President Bush's top foreign policy adviser.

Interviews and profiles of Mr Libby portray a man very different to Karl Rove, the bustling, bare-fisted Texan strategist who has also been named as a key figure in the CIA leak inquiry. Unlike some of his White House colleagues, Mr Libby is proud of his academic achievements - he is a graduate of Yale and Columbia - and intellectual reach.

In 1996, he wrote a novel set in early 20th-century Japan that was praised in The New York Times for "its delicate prose and stirring descriptive passages".

Many observers are surprised that Mr Libby, of all the senior figures in the White House, has been caught up in the Valerie Plame affair.

He is known to be discreet, almost mysterious. He refuses to confirm the exact form of his first name - variously reported as Irv, Irving and Irve - and has given various explanations of his nickname, the best known of which is that his father looked down at him as a baby in his crib and said: "He's a Scooter."

In his dealings with journalists, Mr Libby is said to be courteous but cautious, always insisting that his name is never used and, in most cases, "telling you absolutely nothing" according to William Kristol, a conservative columnist .

As if to accentuate the point, Mr Libby's conversations with Judith Miller, The New York Times reporter with whom he allegedly discussed Ms Plame, sound like extracts from a novel.

According to Ms Miller, her most recent meeting with Mr Libby came in August 2003 when she happened to go to a rodeo in Jackson Hole, Wyoming, on the way back from a conference. A man in dark glasses, jeans and a stetson broke away from the crowd and asked her how the conference was.

"I had no idea who he was," wrote Ms Miller in The New York Times last month. '''Judy,'' he said. ''It's Scooter Libby.'''

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