Anwar al-Awlaki, a radical imam in Yemen with alleged terror links, whom Maj. Nidal Hasan corresponded with.
Nidal Malik Hasan in 2007
Nidal Malik Hasan's graduation photo when he completed his M.D. degree in 2003.
Senior Sergeant Mark Todd and Sergeant Kimberly Munley, who both apparently shot Hasan, were interviewed on the Oprah Winfrey Show this week.
Business cards like this one were found in the apartment of Maj. Nidal Malik Hasan.
The sparse one-bedroom apartment of Major Nidal Malik Hasan, charged in the massacre at Fort Hood that killed 13.
Bottles of drugs that Major Nidal Hasan had reportedly prescribed to himself are photographed in his apartment in Texas.
A map showing the location of a mass shooting at Ft. Hood Army post in Killeen, Texas.
The Army psychiatrist accused of killing 13 people in the Fort Hood massacre told a radical Muslim imam, "I can't wait to join you" in the afterlife, in one of several e-mails exchanged between the two men, ABC News reported on Thursday.
An unnamed official "with top secret access" told the network 18 e-mails were exchanged between Maj. Nidal Malik Hasan and Anwar al-Awlaki, who encouraged Muslims to kill U.S. troops in Iraq, from Dec. 2008 until June of this year.
Other e-mails, the official said, included discussion of when jihad is considered "appropriate," and if it is acceptable for innocent people to die in suicide attacks.
"Hasan told Awlaki he couldn't wait to join him in the discussions they would having over non-alcoholic wine in the afterlife," ABC quoted the official as saying.
Hasan — with an annual salary around $92,000 — also wrote, "My strength is my financial capabilities," the source said. Investigators have found the Army major donated as much as $30,000 per year to Islamic "charities." American authorities have found several such charities to be conduits to terrorist networks.
A military analyst told ABC: "It sounds like code words ... That he's actually either offering himself up or that he's already crossed that line in his own mind."
A joint terrorism task force overseen by the FBI learned late last year of Hasan's repeated contact with al-Awlaki. The FBI said the task force did not refer early information about Hasan to superiors because it concluded he wasn't linked to terrorism.
Secretary of Defense Robert Gates called it disturbing that Hasan has e-mail contact with the radical cleric in Yemen, but stressed that his review is separate from the criminal investigation into Hasan and should not be interpreted as a finger-pointing exercise against Muslims or anyone else.
Investigators have said e-mails between Hasan and the imam did not advocate or threaten violence. After the shootings, al-Awlaki's Web site praised Hasan as a hero.
Gates would not comment Thursday on whether he considers the Fort Hood attack a terrorist act. Sen. Joseph Lieberman, an independent, told a Senate hearing that he does, and urged a government investigation "to learn whether the federal government could have acted in a way that would have prevented these murders from occurring."
Sen. Susan Collins, a Republican, questioned whether the government failed to connect dots about Hasan.
"We must better understand why law enforcement, intelligence agencies and our military personnel system may have failed in this case," Collins said.
An attorney for Hasan says his client will have his first court hearing inside his hospital room at the Brooke Army Medical Center in San Antonio Saturday.
The hearing is to determine whether Hasan will be placed in pre-trial confinement — which usually means jail. But John Galligan says he'll argue that Hasan should remain in intensive care because he is paralyzed and still needs hospital care.
Hasan's psychiatry supervisors at Walter Reed Army Medical Center had expressed concerns in May 2007 about what they described as Hasan's "pattern of poor judgment and lack of professionalism."
President Barack Obama already has ordered a review of all intelligence related to Hasan, including his contacts with al-Awlaki, concerns raised about Hasan by some of his medical colleagues, and whether warnings were properly shared and acted upon within government agencies. Results of that inquiry are due Nov. 30.
The Pentagon said Thursday it will scour its procedures for identifying volatile U.S. military service members hidden in the ranks following the Fort Hood shooting rampage and lapses that might allow others to slip through bureaucratic cracks.
"It is prudent to determine immediately whether there are internal weaknesses or procedural shortcomings in the department that could make us vulnerable in the future," Defense Secretary Gates said.
A 45-day emergency investigation will examine personnel, medical, mental health, discharge and other policies in all corners of the vast Defense Department. It will also look at ways to improve security and emergency response at Defense Department facilities.
"The shootings at Fort Hood raise a number of troubling questions that demand complete but prompt answers," Gates told a Pentagon news conference.
The quick review will be led by two former Pentagon officials, former Army Secretary Togo West and former Navy chief Vernon Clark.
A longer, second review lasting about six months will look at what Gates called "systemic institutional shortcomings." Gates, who has fired several top officials in three years heading the Pentagon, did not address any possible consequences of the inquiries he announced Thursday.
Gates broached little new information about the case of Hasan, the Army psychiatrist accused of killing 13 people and wounding more than 30 in the shootings at the Texas military post on Nov. 5.
Both Gates and Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, said the chief goal of the Pentagon probe is preventing another such attack and improving future responses by disaster teams.
West was Army secretary in the mid-1990s and later became secretary of veterans affairs. Clark was the chief of naval operations from 2000 to 2005.
In 2007, Gates named West co-chairman of a panel created to review rehabilitation care problems at the Walter Reed Army Medical Center in Washington and the National Naval Medical Center in suburban Bethesda, Maryland.
In 1995, as President Bill Clinton's Army Secretary, West ordered a review of the Army's racial climate, including whether there were ties between extremist groups and members of the military. The investigation was prompted by the arrests of two paratroopers in connection with the murders of two black people and concerns that the two men may have had ties to white supremacist groups.
The Associated Press contributed to this report.