KETR

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.

Five men convicted in a recent wave of high profile domestic terrorism cases are now in special communications management units (CMUs) in the American Midwest, where their conversations are monitored 24 hours a day by counterterrorism analysts at the U.S Bureau of Prisons in West Virginia.

A new analysis by NPR's Investigations unit shows several new arrivals into the secretive CMU units, based in Terre Haute, Ind. and Marion, Ill.: