Washington ? Investigators questioned Vice President Dick Cheney recently in the probe of who in the Bush administration leaked the name of a covert CIA operative last year, a source familiar with the investigation said Saturday.

The interview of the vice president follows an acknowledgment by President Bush that he has consulted with a private attorney regarding the probe, indicating that Bush, also, expects to be questioned.

A federal grand jury in recent months has questioned numerous White House and administration officials to learn who revealed the name of CIA operative Valerie Plame, wife of former Ambassador Joseph Wilson, to the news media.

Disclosure of an undercover officer’s identity can be a federal crime.

Cheney’s office said last week that if the vice president were to seek counsel on any issue, he would turn to Terrence O’Donnell, a senior partner in the Washington law firm of Williams & Connelly. Cheney has consulted with O’Donnell for years.

“Given the fact that there is an ongoing investigation, it is appropriate to refer requests for comment to the Office of Special Counsel,” said Cheney spokesman Kevin Kellems.

U.S. Atty. Patrick Fitzgerald of Chicago, whose office declined to comment, was chosen to run the investigation in late December after Atty. Gen. John Ashcroft disqualified himself from the politically sensitive case to avoid an appearance of conflict of interest.

Cheney was not under oath when he was questioned, according to the source, who spoke on condition of anonymity because the investigation involves a criminal matter. The source did not know what Cheney said or what he was asked or whether he had an attorney present. But the central issue of the investigation is who disclosed Plame’s name.