The FBI issued a press release today, November 9, in which they said Major Malik Nidal Hasan was noticed by them as early as December 2008. His activities at the time attracted the interest of "one of their Joint Terrorism Task Forces (JTTFs)." Hasan was communicating with the subject of an unrelated investigation by the JTTF team.
They stated that a review of the interaction between Hasan and the subject of the JTTF investigation was explainable by his position as a psychiatrist at the Walter Reed Medical Center. The content of the communications was consistent with his research. They said nothing else derogatory was found. This led them to conclude that "Major Hasan was not involved in terrorist activities or terrorist planning." They also said other communications of which they were aware were similar to the ones reviewed by the JTTF.
The press statement did not elaborate as to the nature of those communications or exactly why they believed them to be consistent with Major Hasan's research.
The FBI stresses that "at this point, there is no information to indicate had any co-conspirators or was part of a broader terrorist plot." Yet, they did not seem to rule out the possibility that the suspect was a lone actor in a terrorist act - only that he acted alone.
They are examining forensic evidence to ascertain Hasan's motive for the massacre. However, they are limited as to what they can disclose to the public at this time.
The Army Criminal Investigative Division is leading the investigation with the assistance of the FBI and the Texas Rangers. As with any criminal investigation the suspect is presumed innocent.