Army Maj. Nidal Hasan, the accused killer of 13 at Fort Hood last month, "sent 18 e-mails to a radical imam in Yemen before the Fort Hood shootings, but law enforcement officials in Washington who were looking into his behavior saw only two of them," NPR's Dina Temple-Raston reports.

Dina writes that "confusion between two FBI field offices kept law enforcement officials from reviewing all pertinent information about Hasan, investigators told NPR."

Click here for much more of NPR's coverage of the Fort Hood shootings.