Witnesses at the trial of former White House aide Lewis Libby have testified that he discussed the identity of a CIA agent before he has admitted doing so.
Lewis Libby says he forgot conversations about Valerie Plame
Mr Libby, former chief of staff to Vice-President Dick Cheney, told FBI investigators that he learned Valerie Plame's identity from a reporter.
But Mr Cheney's spokeswoman Cathie Martin told the court that he had discussed Ms Plame days beforehand.
Mr Libby denies five charges including perjury and obstruction of justice.
They carry a combined tariff of up to 30 years in jail.
The trial in Washington scrutinises the conduct of the White House in the run-up to the Iraq war.
It has been alleged Valerie Plame was "outed" in revenge for her husband's attack on President George W Bush's use of intelligence to justify the war.
Deliberately revealing an agent's name is a serious offence in the US, though the case is not about who leaked her name, but the alleged cover-up.
Mr Wilson argues that his wife was betrayed
Mr Libby told FBI agents and a grand jury investigating the leak that he learned Ms Plame was a CIA agent from reporters.
But several witnesses have told the trial in Washington that they had already spoken about her with Mr Libby.
Ms Martin said when Ms Plame's husband, Joseph Wilson, criticised Mr Bush for citing intelligence suggesting Saddam Hussein was trying to buy uranium from Niger - even though he had debunked those claims after visiting Niger - she phoned the CIA to see who had sent Mr Wilson to the African country.
The CIA spokesman told her that Mr Wilson's wife worked for the CIA.
When she was told this, she said, she immediately passed on the information to Mr Libby and Mr Cheney.
Other witnesses have testified that Ms Plame conceived the idea for the trip.
Prosecutors aim to show that Mr Cheney's office wanted to make her involvement clear to reporters, to weaken Mr Wilson's accusations, and therefore deliberately leaked her name and identity.
Mr Libby says he did not lie about the date he heard about Ms Plame's identity, but simply forgot the previous conversations at a time when his priority was national security.
It is thought prosecutors will claim his priority at the time was actually to undermine Mr Wilson.