Margot Williams

Known or suspected terrorists who cooperated with federal investigators in at least six major terrorism investigations over two decades were granted protection under the federal witness protection program –- and two of them temporarily could not be found by federal authorities, according to a report from the Justice Department's inspector general.

Opening statements are set to begin Thursday in Boston at the trial of Tarek Mehanna, a 29-year-old American charged in U.S. District Court with conspiracy and providing material support to al-Qaida, as well as planning to attend training camps abroad and making false statements to authorities. He faces a possible life sentence if convicted.