What is known so far:

Does the assault have a link to terrorism?

The FBI has not concluded that Syed Farook, 28, and his wife, Tashfeen Malik, 27, were terrorists – only that investigators have gathered enough preliminary information to move their probe in that direction.

That’s a step beyond earlier this week, when police said they knew nothing conclusive about the possible motivation of Farook or his wife.

David Bowdich, assistant director of the FBI’s Los Angeles office, said Friday that the shooters tried to destroy evidence, including crushing two cellphones and discarding them in a trash can.

A U.S. law enforcement official said Friday that Malik, who later died with Farook in a gunfight with police, used an alias on Facebook to make her declaration of support for the Islamic State and its leader. But there is no sign anyone from the group communicated with her or provided any guidance for the attack.

FBI Director James Comey noted the bureau’s investigation so far has shown no evidence that the suspects were part of a larger group or members of a terror cell.

What did Farook’s family know?

Nothing, according to attorneys David Chesley and Mohammad Abuershaid, who represent Farook’s mother and three siblings.

Farook’s mother, Rafia Sultana Farook, lived with the couple in a modest Redlands apartment but never saw anything that would suggest they were planning a massacre at a holiday party for Farook’s co-workers or building explosives for use in the attack, the attorneys told reporters in Los Angeles. The mother stayed mostly to herself at the home, upstairs, and “everyone was in shock” after details of the rampage emerged, Chesley said.

Family and friends have expressed disbelief that the quiet, religious couple staged the deadly attack.

Who is Tashfeen Malik?

In the days since the shooting, only sparse details have emerged about her life.

Farook told friends he met his future wife online and she was Pakistani. Malik arrived in the United States on a K-1 visa for fiancées and with a Pakistani passport in July 2014, authorities said.

The two were married Aug. 16, 2014, in nearby Riverside County, according to their marriage license. Both listed their religion as Muslim. The couple had a 6-month-old daughter; they left the baby with relatives Wednesday morning before the shooting.

Pakistani intelligence officials say Malik moved as a child with her family to Saudi Arabia 25 years ago. They say the family is originally from the Pakistani town of Karor Lal Esan, about 200 miles southwest of the capital of Islamabad in Punjab province. Malik didn’t stay in Saudi Arabia, eventually returning to Pakistan and living in the capital, Islamabad, though she returned to Saudi Arabia for visits.

Are there any other indications of a possible terrorism link?

On Thursday, a U.S. intelligence official said Farook had been in contact with known Islamic extremists on social media.

But the official said the contact was with “people who weren’t significant players on our radar” and dated back some time. There also was no immediate indication of any “surge” in communication ahead of the shooting.

Farook had no criminal record, and he and his wife weren’t on the FBI’s radar before the shooting. Also, police are looking at the possibility that the shooting was tied to a workplace dispute.

Investigators say they had more than 1,600 bullets with them when they were killed and well over 4,500 rounds of ammunition at their home. Chesley said it wasn’t unusual for gun owners – Farook owned two pistols, and also had two rifles – to buy thousands of rounds of ammunition to save money.

– The Associated Press