Judy Miller

WaPo:

Fitzgerald may learn more details from Cooper's notes. Sources close to the investigation say there is evidence in some instances that some reporters may have told government officials -- not the other way around -- that Wilson was married to Plame, a CIA employee.
...
It is a felony to knowingly identify a covert CIA operative. But lawyers for some media say they believe Fitzgerald has no evidence that a government official committed that crime. Time Inc. argued last week to Hogan that Fitzgerald may have evidence that an official perjured himself during the investigation, but contended that the effort to prove that does not justify jailing reporters.

So why does Fitzgerald want these two reporters to testify? Because one of them - most likely Judy Miller - leaked the name of Valerie Plame to White House officials. Someone else, most likely Rove or Libby, at some point in their grand jury testimony denied identifying Plame or - more likely - denied knowing she worked undercover for the CIA - thereby perjuring themselves.

So, how's this for a theory? The day Wilson goes public - Bush apologist Judy Miller calls up Karl Rove, ostensibly to get his reaction, and in the course of the conversation explains that Wilson's wife is CIA, that perhaps this is revenge for a war the CIA didn't fully support. This information works it's way to Novak, Pincus, Cooper, et. al. who are being told things like, "Talk to Judy Miller" or, "We hear his wife works for the CIA." Once Novak publishes his column, thinking he's in the clear, Rove pounces, calling water-boy Matthews saying Plame is "fair game." However, when it's learned that Valerie Plame uses her maiden name undercover, all hell breaks loose.

This would explain why Miller, Cooper and Rove are under such pressure. What exactly Cooper knows may help confirm what Fitzgerald already suspects is the connection between Rove and Miller - minus Miller's testimony - and also explains why he is adamant that this isn't about 1st amendment rights. If Fitzgerald suspects Miller to be the source of the leak of plane's name, one can understand his frustration at being told by the New York Times that what he's attempting to do is a violation of press freedoms.