The federal prosecutor investigating the leak of an undercover CIA officer's name says his work is complete except for one large omission: hearing from two reporters who are fighting a court order to answer questions under oath.

Chicago U.S. Attorney Patrick Fitzgerald said the refusal of Matthew Cooper (search) of Time magazine and Judith Miller (search) of The New York Times to divulge their sources has stalled his probe.

Neither Cooper nor Miller wrote the original story that revealed the identity of CIA officer Valerie Plame (search). Her name was first published in a 2003 column by Robert Novak, who cited two unidentified senior Bush administration officials as his sources.

It is unclear whether Novak has cooperated with the investigation or whether the grand jury hearing evidence has returned any indictments. Fitzgerald is trying to determine who leaked the name and whether that was a crime.

"By October 2004, the factual investigation — other than the testimony of Miller and Cooper and any further investigation that might result from such testimony — was for all practical purposes complete," Fitzgerald said in two filings asking the U.S. Court of Appeals for the District of Columbia to end its consideration of the case.

A three-judge appellate panel in February upheld a lower court ruling ordering Cooper and Miller to talk. They are asking the full appellate court to reverse the order.

"The public's right to have this investigation concluded should be delayed no further," Fitzgerald said, opposing the request.

The filings, submitted in late March, were first reported by Newsday.

Floyd Abrams, who is representing both reporters, said Fitzgerald has not explained why the reporters' testimony is important to his case.

"He doesn't indicate that it's crucial, just that it's unresolved," Abrams said Wednesday. "He's done with everyone else, done with Robert Novak one way or the other and done inquiring of various government officials."

Novak has refused to say whether he has testified or been subpoenaed.

The column appeared after Plame's husband, former Ambassador Joseph Wilson (search), wrote a newspaper opinion piece criticizing the Bush administration's claim that Iraq had sought uranium in Niger. The CIA had asked Wilson to check out the uranium claim. Wilson has said he believes his wife's name was leaked as retaliation for his critical comments.

Disclosure of an undercover intelligence officer's identity can be a federal crime if prosecutors can show the leak was intentional and the person who released that information knew of the officer's secret status.

Cooper is a White House correspondent for Time who has reported on the Plame controversy. He agreed in August to provide limited testimony about a conversation he had with Lewis "Scooter" Libby (search), Vice President Dick Cheney's chief of staff, after Libby released Cooper from his promise of confidentiality.

Fitzgerald then issued a second, broader subpoena seeking the names of other sources.

Miller gathered material for an article about Plame but never wrote a story.

Prosecutors have interviewed President Bush, Cheney, then-Secretary of State Colin Powell (search) and other current or former administration officials in the investigation. Journalists from NBC and The Washington Post also have been subpoenaed.