The FBI and the Army on Sunday were investigating whether the military psychiatrist suspected in the Ft. Hood shooting rampage had an association with militants at a mosque in Virginia or in cyberspace.
A senior federal law enforcement official said there was no immediate evidence of such a link, nor of any direct connection between the suspected gunman, Army Maj. Nidal Malik Hasan, 39, and terrorist groups or individuals, either in person or online. Hasan is accused of opening fire at a readiness center in Ft. Hood, Texas, on Thursday, killing 13 and wounding dozens. He reportedly had been depressed about his upcoming deployment to Afghanistan.
But authorities are still scouring "voluminous" hard drives, multiple e-mail accounts and website trails "to see what's out there, and to see what it all means," said the official, who spoke on condition of anonymity because the investigation is ongoing. "There's a lot of work being done."
The official said investigators were looking into Hasan's association with the Dar al Hijrah Islamic Center in Falls Church, Va., in early 2001, about the same time that a radical Islamist prayer leader and two of the Sept. 11 hijackers were there.
The mosque is one of the biggest in the United States, and the official cautioned that thousands of people go there for prayer services and other events. The funeral of Hasan's mother was held there on May 31, 2001, the Associated Press reported.
Authorities were focusing aggressively on whether Hasan more recently had been following the fiery online sermons and blog postings of that imam, Anwar al Awlaki, the official said.
Awlaki, a U.S. citizen, left the United States in 2002 and is believed to be in Yemen. He is actively supporting the Islamist jihad, or holy war against the West, through his website.
Early this morning, after Awlaki's name was publicly linked to Hasan's, a posting on Awlaki's site was titled "Nidal Hassan Did the Right Thing."
In it, a writer claiming to be Awlaki described Hasan as a hero and "a man of conscience who could not bear living the contradiction of being a Muslim and serving in an army that is fighting against his own people."
"Nidal opened fire on soldiers who were on their way to be deployed to Iraq and Afghanistan. How can there be any dispute about the virtue of what he has done? In fact the only way a Muslim could Islamically justify serving as a soldier in the U.S. army is if his intention is to follow the footsteps of men like Nidal," the writer said.
There was no way to confirm immediately whether the posting was actually from Awlaki.
The London Telegraph first reported the potential link between Hasan and the mosque.
In recent days, authorities poring over Hasan's computer, Internet records and multiple e-mail accounts have found evidence that he visited other radical Islamist websites with some frequency, according to several officials familiar with the investigation.
"Obviously, people who visit these websites can be influenced by or affected by them, by the influence of the clerics, as opposed to being directed by them," said the senior federal law enforcement official. "It goes back to his state of mind."
Some counter-terrorism officials and experts said that although Hasan's connections to Awlaki, if any, are unclear, the imam has had a major effect on aspiring violent extremists around the world.
"Awlaki is one of the principal jihadi luminaries for would-be homegrown terrorists," said Evan Kohlmann, a terrorism consultant for the U.S. and other governments. "His fluency with English, his unabashed advocacy of jihad and mujahideen organizations, and his Web-savvy approach are a powerful combination."
Kohlmann said Awlaki's lecture on "Constants on the Path of Jihad" -- based on a similarly named document written by the founder of Al Qaeda in Saudi Arabia -- is the "virtual bible for lone-wolf Muslim extremists."
FBI agents and military investigators continued to work methodically to retrace Hasan's steps in an effort to determine what might have set him off and who, if anyone, might have known about his alleged plans.
There was no indication from a thorough search of his computer and other seized evidence that the suspect had any conspirators, federal law enforcement officials said, but they were not willing to rule that out.
Those officials said that Hasan's apparent interest in websites focusing on radical Islamist ideology came at a time when he had grown increasingly -- and publicly -- unhappy with the U.S. war effort and his possible deployment.
"There is nothing that we have found thus far linking him to a terrorist group, but we have intelligence that he made postings in chat rooms," said Scott Stewart, vice president of tactical intelligence for Stratfor, a Texas-based private firm that gathers intelligence for corporations and divisions of the U.S. and foreign governments. He said the group got its information from open-source intelligence on the Internet and elsewhere, and from authorities of various agencies involved in the investigation into Hasan.
"Everything that I'm seeing so far is that he was a lone wolf. It does seem that there was a religious element to this, but there could have been some other workplace violence issues too, since it seems he was a loner who had few friends," Stewart said. "But it's hard to separate sometimes, especially with a lone-wolf actor, where the mental disturbance ends and the religious convictions and political beliefs start."
Meanwhile, the chairman of the Senate Homeland Security Committee, Joe Lieberman (I-Conn.), said he wanted to launch a congressional investigation into the shooting.
"If Hasan was showing signs, saying to people that he had become an Islamist extremist, the U.S. Army has to have zero tolerance," Lieberman said on "Fox News Sunday." "He should have been gone."
But Army Chief of Staff George W. Casey Jr. urged caution and said it was too early to arrive at conclusions about the suspect's motives. Casey warned on ABC's "This Week" that focusing on Hasan's ties to Islam could "heighten the backlash" against enlisted Muslims.
Hasan's relatives have said that he was taunted for his faith. They have also said that he was a good doctor and, if he was the shooter, must have snapped.