WASHINGTON -- Maj. Nidal Hasan, the Army psychiatrist accused of killing 13 at the Fort Hood, Texas, Army base, communicated 10 to 20 times with a radical Islamic cleric in Yemen who on Monday called Maj. Hasan a "hero" and criticized U.S. Muslim groups that condemned the killing spree.

Federal officials said Monday that terrorism investigators conducted a summary look into the contacts that began last year and continued into this year between Maj. Hasan and Anwar al-Awlaki. Mr. Awlaki was once the imam, or spiritual leader,...