Updated at 9:23 p.m. EST
Federal law enforcement officials said the suspected Fort Hood, Texas, shooter had come to their attention at least six months ago because of Internet postings that discussed suicide bombings and other threats.
The officials said the postings appeared to have been made by Maj. Nidal Malik Hasan, who was first reported dead, but is now known to be custody following a shooting incident that left least 13 dead and 31 wounded. The officials said they are still trying to confirm that he was the author and an official investigation was not opened.
The officials spoke on condition of anonymity because they were not authorized to discuss the case.
More coverage of the tragedy at Fort Hood:
Ft. Hood Suspect ID'd as Army Psychiatrist
Soldier Opens Fire at Ft. Hood; 13 Dead
What was Shooter's Motive?
U.S. Army Base Violence Has Bloody History
Obama: Fort Hood Shooting "Horrific"
Fast Facts: Fort Hood
Tragedy at Fort Hood
CBS News reports that Hasan, 39, is a licensed psychiatrist who has lived in Bethesda and Silver Spring, Md. and Roanoke, Va. A spokesman for Texas Sen. Kay Bailey Hutchison says Hasan was upset about an upcoming deployment to Iraq.
One of the Web postings that authorities reviewed is a blog that equates suicide bombers with a soldier throwing himself on a grenade to save the lives of his comrades.
The posting originated with an essay posted on Scribd.com, the popular document-sharing Web site, which argued that suicide bombings were not authorized by Islamic law. It said, for instance, that "it should be quite obvious that all of the 'evidences' used to justify suicide bombing by way of analogy are rather tenuous."
A subsequent, poorly-spelled comment from a user named "NidalHasan" posted in May 2009 seemed to take issue with that analysis. "If one suicide bomber can kill 100 enemy soldiers because they were caught off guard that would be considered a strategic victory," the comment said. "You can call them crazy i [sic] you want but their act was not one of suicide that is despised by Islam."
It's difficult to know from a single comment, of course, if that "NidalHasan" was the account used by the same person now in custody after the shooting. A public records search lists at least half a dozen people in the United States with the same first and last name.
After news of the shooting began to spread on Thursday, Internet pranksters quickly took action. On Vitals.com, a Web site featuring profiles of doctors, someone posted a comment purporting to be from a "conscientious objector" treated by Hasan. A statement from Vitals.com said the comment -- featuring yesterday's date stamp -- was nevertheless posted an hour after the shooting and appears to be "fictitious."