Obama: 'We are a Nation That Endures'

President Barack Obama and the first lady arrived early to speak with wounded soldiers and their families. Mr. Obama addressed the Fort Hood community during the service, hailing the valor of the first responders and denouncing the attack as "twisted."

"It may be hard to comprehend the twisted logic that led to this tragedy," he said. "But this much we do know -- no faith justifies these muderous and craven acts; no just and loving God looks upon them with favor. And for what he has done, we know that the killer will be met with justice- in this world and the next."

Listen to President Obama's remarks at the memorial service:

Army Chief of Staff Gen. George Casey also spoke, lauding the "uplifting" and "heroic" actions of those first on the scene.

"Those who have fallen did so in service of their country," he said. "Yet their willingness to sacrifice... is a great strength of our nation."

On Tuesday, new details emerged about the suspected gunman, army psychiatrist Maj. Nidal Malik Hasan. Hasan allegedly warned Army physicians more than a year ago of “adverse events” if the military did not allow Muslim soldiers to be released as conscientious objectors rather than forcing them to fight against other Muslims, the Washington Post reported.

In June 2007, while serving as a senior resident at Walter Reed Army Medical Center in Washington, D.C., Hasan made a presentation to supervisors and about 25 other mental health staffers, lecturing on Islam, suicide bombers and potential threats to the military from Muslims fighting wars in Iraq and Afghanistan, according to the Post.

"It's getting harder and harder for Muslims in the service to morally justify being in a military that seems constantly engaged against fellow Muslims," he said, according to a copy of the presentation obtained by the Post.

The revelations come on the heels of new information released on Monday connecting Hasan to the radical cleric Anwar al-Awlaki, a former imam at the Virginia mosque Hasan once attended. Intelligence agencies intercepted 10 to 20 messages to Awlaki, and monitored Hasan long before his deadly attack at Fort Hood, reported the New York Times.

Federal authorities dropped the inquiry, however, believing that the messages did not suggest a threat of violence.

"At this point, there is no information to indicate Maj. Nidal Malik Hasan had any co-conspirators or was part of a broader terrorist plot," the FBI said in a statement Monday.

Rep. Peter Hoekstra of Michigan, the ranking Republican on the House Intelligence Committee, denounced intelligence officials on Monday and criticized authorities for ignoring warning signs.

The correspondences might have seemed insignificant at the time, however "for me, the number of times that this guy tried to reach out to the imam was significant," Hoekstra told the Dallas Morning News.

Hasan, 39, remains in a San Antonio hospital under guard. He was shot four times. FBI and Army investigators tried to interview him on Sunday, but he invoked his right to counsel, senior government officials said. Hasan will reportedly be charged by the U.S. military rather than in a civilian court.

On Monday, Hasan's family hired retired Army Col. John P. Galligan, a former military judge at Fort Hood, to be his attorney. Galligan said he planned to speak with Hasan on Monday night.

---- Compiled from wire reports and other media sources