CIA Leak Investigation Could Entangle President's Closest Aides

Indictments in the ongoing investigation into who leaked the name of a CIA operative working undercover could come as early as this week, and two powerful players at the White House could be caught in the cross hairs -- President Bush's senior adviser and chief political strategist, Karl Rove, and Vice President Dick Cheney's chief of staff, I. Lewis "Scooter" Libby.

The investigation began after someone disclosed to the press the identity of CIA officer Valerie Plame. Plame is married to retired U.S. diplomat Joe Wilson, who had been critical of the Bush administration's case for the war in Iraq. Wilson says his wife's name was leaked to discredit him.

When the investigation was first launched, it seemed a nearly impossible case to prosecute. First, reporters don't talk about confidential sources:

"In all due respect to your profession [journalism], you do a very good job of protecting the leakers," the president told reporters during a press conference earlier this month.

Second, the law that makes it a crime to reveal an undercover agent has almost never been enforced. The law's author says it sets a high bar:

"The person revealing the information must absolutely know that the government is taking measures to protect this person's identity," said Victoria Toensing, former U.S. deputy assistant attorney general.

But when special prosecutor Patrick Fitzgerald threatened to jail reporters who did not reveal sources, Time magazine writer Matthew Cooper revealed his source was Rove.

New York Times reporter Judith Miller went to jail for 85 days before finally revealing her source was Libby.

Now the reporters' testimony raises the possibility of additional charges:

Perjury -- If either Rove or Libby denied talking about Wilson's wife to reporters, that could put them in direct conflict with the reporters who told the grand jury they did.

Obstruction of justice -- In a letter Libby wrote to Miller in jail, he told her all other reporters had testified "they did not discuss Ms. Plame's name or identity" with him. Libby could face charges that he was trying to influence her testimony.

Lawyers familiar with the case say Fitzgerald also may be looking at broader conspiracy charges if the investigation finds that White House staffers conspired to illegally leak classified information.

Even as the universe of possible charges expands, there is yet another possibility. Fitzgerald could decide to end his investigation with no charges at all. Only Fitzgerald knows for sure, and he's not talking.

ABC News' Jonathan Karl filed this report for "World News Tonight."