Secretary of State Colin Powell recently testified before a federal grand jury investigating the leak of the identity of CIA covert officer Valerie Plame, NEWSWEEK has learned. Powell's appearance on July 16 is the latest sign the probe being conducted by prosecutor Patrick Fitzgerald is highly active and broader than has been publicly known. Sources close to the case say prosecutors were interested in discussions Powell had while with President George W. Bush on a trip to Africa in July 2003, just before Plame's identity was leaked to columnist Robert Novak. A senior State Department official confirmed that, while on the trip, Powell had a department intelligence report on whether Iraq had sought uranium from Niger--a claim Plame's husband, Joseph Wilson, discounted after a trip to Niger on behalf of the CIA. The report stated that Wilson's wife had attended a meeting at the CIA where the decision was made to send Wilson to Niger, but it did not mention her last name or undercover status. At the time, White House officials were seeking to discredit Wilson, who had become a public critic of the Bush administration. There's no indication Powell is a subject of the probe; the department official said the secretary never talked to Novak about the Plame matter. Still, sources say the decision to question Powell shows the thoroughness with which Fitzgerald is conducting the probe--and that knowledge about Plame was circulated at the highest levels of the administration. Though most lawyers thought the investigation was nearly complete, sources say Fitzgerald has recently recalled witnesses before the grand jury--apparently to ask about issues raised by a new Senate intelligence committee report that seemed to contradict some of Wilson's public statements about Plame's role in his trip to Niger.