FBI agents investigating the disclosure of a CIA officer's identity have begun by examining events in the month before the leak, when the CIA, the White House and Vice President Cheney's office first were asked about former ambassador Joseph C. Wilson IV's CIA-sponsored trip to Niger, according to sources familiar with the probe.

[Robert D. Novak] has said he began interviewing [Bush] officials about Wilson shortly after July 6, asking why such an outspoken Bush policy critic was picked for the Niger mission. Novak reported that Wilson's wife worked at the CIA on weapons of mass destruction and that she was the person who suggested Wilson for the job.

On July 17, the Time magazine Web site reported that "some government officials have noted to Time in interviews, (as well as to syndicated columnist Robert Novak) that Wilson's wife, [Valerie Plame], is a CIA official who monitors the proliferation of weapons of mass destruction." On July 22, Wilson appeared on NBC's "Today" show and said that disclosing the name of a U.S. intelligence officer would be "a breach of national security," could compromise that officer's entire network of contacts and could be a violation of federal law.