intimidation of witnesses

i've been a bit busy this week - but i somehow missed the leopold article (or at least some of the detail) referred to in this piece

"More than two dozen e-mails related to CIA agent Valerie Plame and her husband, former Ambassador Joseph Wilson, are missing, according to investigative reporter Jason Leopold. The messages were sent to several senior members of the George W. Bush administration between May 2003 and July 2003.

Special Prosecutor Patrick Fitzgerald suspects these messages may have been destroyed.

[snip]

Knowledgeable sources close to the investigation said the e-mails were sent by Libby, Deputy White House Chief of Staff Karl Rove, then Deputy National Security Adviser Stephen Hadley, former CIA official Frederick Fleitz, former aide to Vice President Dick Cheney, John Hannah, former Cheney National Security assistant David Wurmser, former Under Secretary of State for Arms Control and International Security Affairs John Bolton and White House Chief of Staff Andrew Card.

Leopold reported Fitzgerald also believes some e-mails sent to Vice-President Cheney by Libby and some senior officials of the CIA, as well as the replies, were not turned over to his staff.

[snip]

Fitzgerald’s staff, after combing through thousands of documents obtained in the investigation to date, was unable to locate the messages described. The Special Prosecutor became suspicious about possible evidence destruction only a few weeks after he took charge of the investigation early in 2004. By that time, sources said, he already believed Rove and Libby were impeding his investigation.

Fitzgerald received a tip in the early stages of the investigation that Karl Rove might have withheld or destroyed an e-mail that would have implicated him in the Plame leak. Sources said in January 2004, Fitzgerald sent a letter to his boss, then acting Attorney General James Comey, asking for confirmation that he had the authority to investigate and prosecute individuals for additional crimes, such as obstruction of justice, perjury and destroying evidence. Up to that point, the probe had been closely focused on a little-known federal law making it a felony for any government official to knowingly reveal the identity of an undercover CIA officer.

Comey confirmed Fitzgerald’s authority in February 2004, saying he had the power to prosecute “perjury, obstruction of justice, destruction of evidence, and intimidation of witnesses.”"

i'm quite interested in that last paragraph. i'd previously kinda assumed that the list - “perjury, obstruction of justice, destruction of evidence, and intimidation of witnesses” was boilerplate language - however we now know that fitz was specifically looking into items 1, 2 and 3. is it possible that there was evidence of 4 - "intimidation of witnesses” as well?

i'd love to know what Fitz knows about that...