WASHINGTON -- U.S. Sen. Susan Collins wanted to know if 13 people died at Fort Hood earlier this month because someone failed to "connect the dots." U.S. Sen. John McCain, R-Ariz., wanted to know if "political correctness" prevented the Army from identifying Army psychiatrist Maj. Nidal Hasan as a potential threat to his fellow soldiers.

Senators examined those questions and others Thursday during a Senate Homeland Security and Governmental Affairs Committee hearing that focused on Hasan's Nov. 5 shooting rampage at the Army post in Texas, where 12 soldiers and one civilian were killed and 29 others injured. Hasan has been charged with 13 counts of premeditated murder and could face the death penalty if convicted.

The committee's chairman, U.S. Sen. Joseph Lieberman, I-Conn., said the purpose of the hearing was to investigate whether the shootings "could have been prevented, whether the federal agencies and employees involved missed signals ... in a way that enabled Hasan to carry out his deadly plan."

Lieberman called the shootings a "homegrown terrorist attack."

Collins, the ranking Republican on the committee, compared the information that was available to officials about Hasan before the shootings with the missed warning signs that preceded the terrorist attacks of Sept. 11, 2001.

Collins said the investigations that followed the 2001 attacks uncovered vital information "that might have prevented the deaths and destruction of that terrible day if only the dots had been connected. In the wake of the mass murder at Fort Hood, we once again must confront a troubling question: Was this another failure to connect the dots?"

During the hearing, billed as "The Fort Hood Attack: A Preliminary Assessment," committee members referred to publicly reported information that Hasan, a Muslim, had communicated with a cleric known as an al-Qaida associate and had made statements questioning his military oath to defend the U.S. Constitution. Members and panelists questioned whether this information was shared appropriately and acted upon, and whether Hasan's position in the military or concerns about "political correctness" may have shielded him from inquiry.

"I have talked to military officers who stated that, at least up until now, that they have had a significant reluctance to pursue these implications because of political correctness," McCain said.

Frances Fragos Townsend, former Homeland Security and Counterterrorism Assistant to President George W. Bush, testified at the hearing and echoed the concerns raised by McCain.

"I do fear that because this was a senior member of the military," Townsend said, "there was a reluctance to follow the facts" because of a fear of being criticized.

Collins told reporters after the hearing that the issue deserves further scrutiny.

"I do believe there was a hesitancy to investigate Maj. Hasan due to the fact that there was such a severe shortage of psychiatrists in the Army, and I believe the fact that he was a pretty high-ranking officer may have insulated him from questions," she said. "I think beyond that we need to do more investigative work to reach a conclusion."

Retired Gen. John M. Keane, former Army vice chief of staff, encouraged a review of Department of Defense policies regarding commander response to extremist jihadist behavior. Keane said that racially motivated murders at Fort Bragg, N.C., in 1996 last prompted a review of those policies.

"It should not be an act of moral courage for a soldier to identify a fellow soldier who is displaying extremist behavior; it should be an obligation," Kean testified.

Members and panelists also raised the issue of First Amendment rights and questioned where the line may be drawn for a soldier's freedom to express his or her beliefs.

Lieberman asserted that diversity of religion should be respected but that it "shouldn't be a cover for bad behavior."

Panelists also noted that the Fort Hood attack was hard to predict because Hasan is believed to have acted alone.

"The threat of an American lone wolf in the United States presents that most difficult problem for U.S. law enforcement," said Juan Carlos Zarate, senior advisor for the Center for Strategic and International Studies.

Thursday's session was the first public hearing related to the Fort Hood incident, but it was the latest in a series of investigations by the Homeland Security Committee into the issue of homegrown terrorism. The committee first examined the issue in 2006 with a hearing on prison radicalization.

Collins and Lieberman scheduled the hearing despite resistance from President Barack Obama, who discouraged congressional hearings to avoid potential "political theater."

Lieberman said the committee was obligated to investigate the shootings.

"We are conducting this investigation because we believe it is our constitutional and legal responsibility to do such oversight of executive branch actions," he said.

Collins said the issue of information-sharing should be investigated further.

"It is clear to me that information that I believe should have been shared was not," she said. "I don't yet know enough about why it wasn't shared, who decided not to share it -- those kinds of critical questions will I hope be answered through our investigation."

Lieberman said the committee will continue to investigate the issue and will hold another hearing "when and if it's appropriate to do so."