The family of the alleged Fort Hood shooter held his mother's funeral at the same Virginia mosque that two Sept. 11 hijackers attended in 2001, at a time when a radical imam preached there.

Whether the Fort Hood shooter associated with the hijackers is something the FBI will probably look into, according to a law enforcement official who spoke on condition of anonymity because the investigation is ongoing.

The family of Maj. Nidal Malik Hasan, the Army psychiatrist who killed 13 and wounded 29 at the Texas military base, held his mother's funeral at the Dar al Hijrah Islamic Center in Falls Church, Va., on May 31, 2001, according to her obituary in the Roanoke Times newspaper.

In 2001, Anwar Aulaqi was an imam, or spiritual leader, at the Washington-area mosque. Aulaqi told the FBI in 2001 that, before he moved to Virginia in early 2001, he met with 9/11 hijacker Nawaf al-Hazmi several times in San Diego. Al-Hazmi was at the time living with Khalid al-Mihdhar, another hijacker. Al-Hazmi and another hijacker, Hani Hanjour, attended the Dar al Hijrah mosque in Virginia in early April 2001.

In his FBI interview, Aulaqi denied ever meeting with al-Hazmi and Hanjour while in Virginia.

Aulaqi, a native-born U.S. citizen, left the United States in 2002, eventually traveling to Yemen. He was investigated by the FBI in 1999 and 2000 after it was learned that he may have been contacted by a possible procurement agent for Osama bin Laden. During this investigation, the FBI learned that Aulaqi knew people involved in raising money for Hamas, a Palestinian group on the U.S. State Department's terrorist list.

Imam Johari Abdul-Malik, outreach director at Dar al Hijrah, said he did not know whether Hasan ever attended the mosque but confirmed that the Hasan family participated in services there. Abdul-Malik said the Hasans were not leaders at the mosque and their attendance was utterly normal.

The Falls Church mosque is one of the largest on the East Coast, and thousands of worshippers attend prayers and services there every week. Abdul-Malik said it's a mistake for people to conflate regular attendance at a mosque with extremism.

Many Muslims pray at the mosque multiple times a day, he said. "It's part of family life. It's like going out for ice cream after dinner."

Faizul Khan, former imam of the Muslim Community Center in nearby Silver Spring, Md., where Hasan also worshipped, said he was not aware that Hasan had attended services at Dar al Hijrah but said it would not be unusual for Hasan to attend more than one mosque concurrently.

Khan said he did not recall Hasan mentioning having been taught or preached to by Aulaqi.

The London Telegraph first reported the potential link between Hasan and the mosque.

Army Chief of Staff Gen. George Casey said Sunday it's important for the country not to get caught up in speculation about Hasan's Muslim faith, and he has instructed his commanders to be on the lookout for anti-Muslim reaction to the killings at the Texas post.

He says focusing on the Islamic roots of the suspected shooter could "heighten the backlash" against all Muslims in the military.

Casey says diversity in the military "gives us strength."

Casey declined to answer questions about the investigation into the shooting, but said evidence to this point shows that Hasan acted alone. He toured Fort Hood on Friday with Army Secretary John McHugh.

Casey appeared on ABC's "This Week" and CNN's "State of the Union."