Attorney General Loretta Lynch said Sunday that the FBI is looking into whether the mother of one of the San Bernardino attackers knew anything about the shooting in advance.
"Obviously it's something that we're looking at very, very closely," Lynch told NBC's "Meet the Press," when asked about what the woman may or may have not known before the massacre.
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Law enforcement officials have said that Rafia Farook lived in the same house in Redlands, California where her son, Syed Farook, and his wife, Tashfeen Malik, were building at least 15 pipe bombs and stockpiling thousands of rounds of ammunition.
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Senior law enforcement officials said Sunday they do not yet know whether it was specifically the terror group ISIS that played a significant role in the couple's radicalization.
"At this point, we don't know enough to say whether it was ISIS or something else," one official said.
Another official said there's still no evidence that the couple was in direct contact with any terror groups or individuals overseas leading up to the attack.
The Italian newspaper La Stampa reported Sunday that Farook's father, also named Syed, said that his son agreed with the goal of ISIS leader Abu Bakr al Baghdadi to create an Islamic state.
U.S. officials have said that around the time of the San Bernardino shooting attack, Tashfeen Malik sent a post to her Facebook page pledging loyalty to al Baghdadi.
READ MORE: Tashfeen Malik, mom in California rampage, became very devout
A representative of the newspaper told NBC News that the father said he had been interviewed by the FBI for seven hours.
On "Meet the Press," Attorney General Lynch said the pattern of people in the United States becoming radicalized by a terrorist group's propaganda has become a familiar one.
But as for the couple that committed last week's mass shooting, "We're not sure which one (fanatical ideology) they picked in this case, despite the media accounts."
WATCH: Attorney General Lynch on 'Meet the Press':
Lynch said that after conducting 300 interviews and carrying out several searches, investigators "do not have evidence that they were part of either a larger group or cell, or that they were planning anything else."
Rep. Michael McCaul, R-Texas and chairman of the House Homeland Security Committee, said he's been told that federal investigators are working hard to determine what Malik was doing overseas before she came to the U.S. in 2014 to be Farook's wife.
"There's a serious investigation ongoing into what she was doing in Pakistan and in Saudi, including if she attended the red mosque in Islamabad, which is a very radicalized mosque," he said on "Fox News Sunday."
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