Karl Rove, George Bush's chief political adviser, was today giving evidence for the fourth time to an investigation into the leaking of a covert CIA agent's identity.
Mr Rove, who had unexpectedly offered to give more evidence to a grand jury, made no comment as he arrived at a federal courthouse in Washington.
The two-year inquiry is due to conclude in the next few days and prosecutors will soon decide whether or not to charge anyone.
Last week, the special counsel in the inquiry, Patrick Fitzgerald, said in a letter to Mr Rove's lawyers that he could not guarantee the presidential aide would not be indicted.
Under US court procedures such warnings are required before a witness gives evidence to a grand jury if there is a possibility that the witness could be charged. No such caution was issued before Mr Rove's previous appearances to give evidence in the case.
Today's appearance is likely to be Mr Rove's last chance to convince grand jurors he did nothing criminal in the case.
If Mr Rove is indicted, it will be a huge blow to the Bush administration. Mr Rove has been Mr Bush's closest political aide for more than 10 years, masterminding his election to the Texas governorship and to the presidency.
