Lewis "Scooter" Libby was one of the highest-ranking White House officials ever to stand criminal trial.
Lewis "Scooter" Libby had been seen as Dick Cheney's alter ego
He was enmeshed in the inquiry into the leaking of the identity of a CIA operative - who happened to be the wife of a prominent critic of White House Iraq policy.
As chief aide to Vice-President Dick Cheney, Libby had been involved in almost every major decision made by the Bush administration.
He immediately resigned after a federal grand jury indicted him on five counts in the CIA leak case. They included charges of obstruction of justice, making a false statement and perjury.
He was convicted of all but one of the charges in March 2007. He was sentenced to two-and-a-half years in prison, two years of probation and a fine of $250,000 (£125,000) in June.
But in July, President George W Bush intervened to commute Libby's sentence, describing it as "excessive".
Though no longer required to go to jail, Libby is still due to serve the probation period and pay the fine.
Key Iraq role
Seen as an arch neo-conservative - schooled at Yale by the hawkish former Deputy Defence Secretary Paul Wolfowitz - Libby had been described as "a force multiplier for Cheney's agenda and views".
He played a key role in compiling the White House's allegations over Iraq's weapons of mass destruction, and opponents said he tried to firm up a number of discredited allegations that had been used to build the case against Saddam Hussein.
These included the assertion that a Saddam agent met one of the lead hijackers in Prague in the months before the 9/11 attacks on the US.
Libby also took flak from opponents after reports that he had met Pentagon officials before a substantial contract to repair Iraq's oil fields was awarded to Halliburton - Mr Cheney's old firm.
Libby was a lawyer before becoming an adviser to Mr Wolfowitz at the State Department in 1981, at the start of the Reagan administration.
After another spell in private practice, he returned to Mr Wolfowitz's side in 1991, this time at the Pentagon in the administration of President George Bush senior.
It was there that a policy paper he wrote, calling for the US to build up its military strength to a point at which it could not be challenged, caught the eye of Mr Cheney, who was then defence secretary.
Libby is also an accomplished skier, and the author of a highly praised 1996 novel - The Apprentice, a tale of passion and murder set in rural Japan in 1903.
In a US TV interview to promote the paperback edition of the book in 2002, Libby told host Larry King: "I'm a great fan of the vice-president. I think he's one of the smartest, most honourable people I've ever met.
"So, I'd like to consider myself fully on his team, but there's always a novel kicking around in the back somewhere."
The nickname "Scooter" reportedly derives from the way he scooted about his cot as a baby.