Officials say a joint terrorism task force -- overseen by the FBI -- learned that Nidal Hasan had been communicating with a radical overseas cleric. The information was turned over to a Defense Department investigator for the task force -- who determined that there was no reason to investigate the Army psychiatrist any further.

Officials say the assessment concluded that Hasan's communications with the imam were centered around a research paper he was writing at the time.

The FBI is already conducting its own internal review about how it handled the early information about Hasan, amid questions about whether there were missed opportunities to prevent last week's rampage.