President Barack Obama will attend Tuesday's memorial service for the victims of last week's deadly attack at Fort Hood, Texas.
Thirteen people were killed and 29 were wounded during a gunman's rampage at the U.S. Army base last Thursday.
The chairman of the Senate Homeland Security Committee is calling for a probe into the deadly shooting at the fort.
Senator Joe Lieberman, I-Conn. told Fox News he wants to know whether the army missed warning signs that Major Nidal Malik Hasan was becoming extreme in his Islamic views.
"If Hasan was showing signs, saying to people that he had become an Islamic extremist, the U.S. Army has to have zero tolerance," Lieberman said on Fox News Sunday. "He should have been gone."
And the warning signs seem to have been there. The London Daily Telegraph reported Hasan allegedly gave a lecture to other doctors saying non-Muslims should be beheaded and have boiling oil poured down their throats.
The army psychiatrist also worshipped at the same mosque as two of the September 11 terrorists.
Fellow doctors say Hasan openly claimed to be a Muslim first and American second.
The news has many lawmakers concerned, but maybe not all are surprised.
"A couple of years ago, after a two-year investigation, my committee put out a report that said the new face of terrorism in America would not just be the attacks as 9/11, organized abroad and sending people in here," Lieberman explained. "It would be people within this country, home-grown terrorists, self-radicalized, often over the Internet, going to Jihadist web sites. And there's concern from what we know now about Hasan that, in fact, that's exactly what he was, a self-radicalized home-grown terrorist."
Even the co-founder the Islamic community near Fort Hood told Nidal, "There's something wrong with you."
Army Chief of Staff Gen. George Casey said he doesn't want a backlash against other Muslim soldiers, because of Hassan's actions.