Investigators looking into last week's California massacre think the husband-and-wife shooters may have been preparing their attack for as long as a year.
They say the two practiced at several gun ranges, and they suspect the couple took out a $28,500 bank loan knowing they would never pay it back. One official thought the money was earmarked to take care of the couple's 6-month-old daughter after they were killed.
There are still no signs that U.S.-born Syed Rizwan Farook and his Pakistani wife, Tashfeen Malik, were part of a terror cell or group. But investigators say the pair had been radicalized for some time, and the FBI is looking into the attack as an act of terrorism.
Farook and Malik killed 14 and wounded 21 at a gathering of local government workers at a regional center in San Bernardino, California, east of Los Angeles.
They fled in a car and were gunned down in a shootout with police in a nearby residential neighborhood.
Malik pledged allegiance to an Islamic State militant leader in a Facebook post, and Farook had contact with individuals linked to terror groups.
Officials say the San Bernardino office where the killings took place was heavily damaged and will not reopen until next year.
The guns used in the attack were bought legally by someone who police say is distantly related to Farook by marriage. So far, he is not facing any charges.
In a rare televised address from the Oval Office late Sunday, President Barack Obama again called on Congress to tighten U.S. gun laws. He said no matter how effective law enforcement is, it cannot identify every would-be shooter. He called it a matter of national security to prevent potential killers from getting guns.
He said his administration had hardened its defenses against terrorist threats, and he noted how agents had disrupted countless plots, both at home and overseas.
The president sought to discourage Americans from letting what happened in California turn into a war between the United States and Islam, reminding them that the two killers had embraced "a perverted interpretation of Islam."