Karl Rove (search) and the man who could indict him were in a federal courthouse throughout Friday morning and into the afternoon as President Bush's top political adviser testified in the ongoing investigation into who leaked the identity of a CIA operative.

Rove was in the building for over four hours, and left without speaking to reporters. Instead, his attorney, Robert Luskin, issued a brief statement saying Rove appeared voluntarily.

"Karl C. Rove testified voluntarily today before the grand jury investigating the disclosure of a CIA agent's identity," the statement said. "The Specal Counsel [Patrick Fitzgerald (search)] has not advised Mr. Rove that he is a target of the investigation and affirmed that he has made no decision concerning charges."

Luskin's statement also said Fitzgerald has asked Rove not to discuss his testimony, but did not anticipate the need for Rove to testify further.

Friday was the fourth time Rove has been before that grand jury, which is set to wrap up its term Oct. 28, barring a possible extension.

The investigation centers around the question of who "outed" Valerie Plame (search) as a CIA operative back in 2003 — an action Bush critics say was taken in retaliation for Plame's husband's public criticisms of the White House regarding the Iraq war.

Rove has acknowledged talking to two reporters on the subject, but saying he only spoke about Plame and did not name her or disclose her status at the CIA — whether she was covert or not. At the time of the alleged "outing," Plame was working at CIA headquarters in Langley, Va. Whether or not she technically was considered "covert" at the time of the name leak is part of the controversy.

If Fitzgerald does not obtain an indictment before Oct. 28, he might have to start all over again and presenting evidence and testimony before a brand new grand jury. He could, alternatively, obtain a six-month extension of the grand jury.

Fitzgerald has reportedly declined to assure Rove's attorney that the White House official will not be indicted.

Legal experts say it is not unusual for a witness to be called back before the grand jury, although with repeat appearances comes the risk of inconsistent statements.

White House: 'No Comment'

The White House has gone from issuing strong denials that Rove and Vice President Dick Cheney's chief of staff, Lewis "Scooter" Libby (search), were involved in the leak and promising to fire anyone involved in the leak to a posture of "no comment" on Friday.

After Rove's testimony, White House spokesman Scott McClellan was asked whether Rove still had the president's confidence. He would say only, "Karl continues to do his duties."

McClellan said he was declining to comment on all questions that touched on the grand jury matter. "The president made it very clear, we're not going to comment on an ongoing investigation," he told reporters.

Instead, the spokesman said the president and his staff are focusing on Saturday's constitutional referendum in Iraq, continuing the rebuilding efforts after Hurricane Katrina (search), avian flu (search) concerns and other issues.

In an exclusive interview Friday with FOX News' Brit Hume, Cheney would not discuss the topic.

"I'm simply not at liberty to discuss the issue. I understand you've got to ask those questions, but it is an ongoing investigation, and we're under instructions not to discuss the matter, so therefore I can't discuss the matter," Cheney said.

Watch the Cheney interview on FOX News' "Special Report with Brit Hume" tonight at 6 p.m. EDT.

Whether Rove's involvement in the scandal will hurt the White House remains to be seen, as does what will happen to Rove when the CIA leak investigation is over, political observers told FOX News on Friday.

"Certainly, the specter of this grand jury investigation hanging over the White House doesn't help the president's approval ratings," Washington Times columnist Bill Sammon told FOX News.

But whether Rove will be charged, "it's anybody's guess," Sammon said. "We just don't know what [Special Prosecutor Patrick Fitzgerald] will do."

Democratic strategist Doug Schoen told FOX News that the White House's backing off of Rove and Libby's assertions that they were not involved puts the two men in jeopardy.

"I think they are both at risk and it creates a [political] diversion at the very least," Schoen said.

The spotlight in Fitzgerald's investigation recently has fallen on Libby, who was the focus of prosecutors' questions in two grand jury appearances by New York Times reporter Judith Miller (search).

Miller was recently released after spending more than 80 days in jail over her refusal to testify on the matter. After getting confirmation that she had been released by her confidential source, Libby, to talk, she agreed to testify.

Miller has since discussed her conversations with the vice president's top aide about Plame, and her husband, former ambassador Joseph Wilson (search).

Legal Options

But the legal path that Fitzgerald could take is yet to be determined, FOX News senior judicial analyst Judge Andrew Napolitano told FOXNews.com.

Napolitano says the Intelligence Identities Protection Act of 1982 is the main law that could be used to show criminal wrong-doing, however, it poses a difficult standard for prosecutors to prove.

For one, Rove would have had to have learned Plame's identity from some officially classified source. Learning the identity from a reporter does not meet the test, Napolitano said.

Also, Plame would have to have been covert, but Napolitano said her covert status is highly questionable because of reports that Plame's role with the CIA was widely known throughout Washington.

The government must also prove that it had spent considerable efforts in maintaining her covert identity either at the time of her outing or in the recent past, Napolitano said.

While a specific violation of that law might be difficult to prove, Napolitano said others might not be so complex, and Fitzgerald's historical background leads him to believe that it's likely a charge will emerge.

The grounds for other possible charges include: perjury — lying about subjects directly related to the investigation; a lesser charge for making up information not directly related to the investigation; obstruction of justice; or conspiracy-related charges.

Napolitano said the most worrisome charge likely would be a conspiracy charge related to the 1982 law. For instance, if Rove and Libby agreed at one point to out Plame to get back at Wilson, and either one of them took any action to continue on that agreement, the prosecutor could pursue a conspiracy charge. A conviction on the charge would net no less than four years in prison.

The investigation's roots lie in statements Wilson made in a newspaper column that the administration had twisted prewar intelligence on Iraq. Eight days after Wilson made his allegations, columnist Robert Novak (search) identified Wilson's wife as a CIA operative, saying she had suggested her husband for a mission to Africa for the agency.

Novak said his sources were two senior administration officials. Rove spoke to Novak about Wilson's wife and is apparently one of Novak's sources. The other is still a public mystery. Novak is believed to have cooperated with Fitzgerald's investigation, though he has declined to comment on the matter.

The White House denials of Rove's and Libby's involvement collapsed three months ago, when Time magazine reporter Matt Cooper (search) testified that Rove had been one of his sources for a story that identified Wilson's wife. Libby was another of Cooper's sources for the story.

FOX News' Megyn Kendall, Greg Simmons and The Associated Press contributed to this report.