Did something change in the defense after its opening statement about Rove (Libby "will not be sacrificed so Karl Rove can be protected") that led to its refusal to follow up during the trial? Did the prosecutor have new information that has not yet been made public about Libby and Cheney? If so, that evidence would have been irrelevant to the precise charges against Libby but might have come into play if Libby and Cheney testified. Their appearances might have made them vulnerable to additional perjury and obstruction charges if they were found to have lied on the stand. But who might have proved that?

The missing piece in the extensive evidence and testimony that detailed the administration's concerted attack on Wilson, orchestrated by Cheney, is the conversations among Libby, Cheney -- and Rove. Rove had made a deal with Fitzgerald. Rove changed his testimony, escaped prosecution and went back for a fifth time before the grand jury. Fitzgerald owned Rove.

Only if Libby and Cheney appeared could Fitzgerald cross-examine them about their discussions with Rove, which presumably Rove had already testified about before the grand jury. Rove was the hostile witness against Cheney whom the prosecution had waiting in the wings, the witness who was never called. If Libby had come to the stand in his own defense, and summoned Cheney as well, Fitzgerald might have been prompted to call Rove from the deep to impeach Libby's and Cheney's credibility and reveal new incriminating information about them. Instead, Libby remained silent, Cheney flew off to Afghanistan and Rove never appeared. Rove was the missing witness for the prosecution.