STEVE INSKEEP, HOST:
No matter why two suspects opened fire in San Bernardino yesterday, 14 people are dead. But the motive, if it's ever known, will affect how we think about the attack. Here's what little we do know. One suspect was a coworker of people at a holiday party yesterday. Another was a girlfriend or partner. A man who says he is the brother-in-law of suspect Syed Rizwan Farook has spoken briefly. Reporter Susan Valot was there.
SUSAN VALOT, BYLINE: Farhad Kahn introduced himself as the brother-in-law of alleged shooter Syed Farook. His wife, he says, is Farook's sister. He says the family has no idea why Farook would do something like this.
(SOUNDBITE OF PRESS CONFERENCE)
FARHAD KAHN: I don't have words to express how sad and how devastated I am.
VALOT: Kahn says he and his family are still in disbelief.
KAHN: On behalf of my family, we all are shocked and very sorry for what happened. I mean, you know, we all are just completely shocked. We have no idea that something - this could happen.
VALOT: When reporters tried to ask Kahn more questions about Farook, Hussam Ayloush of the Council on American-Islamic Relations, which hosted the press conference, stopped the questioning. He says the family has no more information to offer.
(SOUNDBITE OF PRESS CONFERENCE)
HUSSAM AYLOUSH: 'Cause we don't know the motives. Is it work, rage-related? Is it mental illness? Is it extreme ideology? At this point, it's really unknown to us, and it's too soon for us to speculate.
VALOT: Kahn was surrounded by local Christian and Muslim clergy. One Christian pastor called on Christians and Muslims to join together in prayer. For NPR News, I'm Susan Valot in Anaheim, Calif.
INSKEEP: So we have more questions than answers, but let's try to frame those questions with David Sterman of the New America Foundation, who joins us once again. And what questions are on your mind, David, as you listen to what little we do know of these suspects?
DAVID STERMAN: So the big one is certainly motivation, but we just don't know yet. One thing a lot of people have been discussing is whether they're U.S. citizens. However, people should not read into citizenship as a marker for motivation.
INSKEEP: This is a question people are asking. We do know, according to the authorities, that Syed Rizwan Farook was born in the United States. That would make him a natural-born American citizen. The other person, Tashfeen Malik - we don't know. Go on.
STERMAN: Right. In fact, if you look at jihadist terrorism cases, eight out of 10 of the people we examined at New America were either U.S. citizens or legal residents.
INSKEEP: Oh, so we cannot assume anything about people's loyalties based on where they were born?
STERMAN: Right.
INSKEEP: OK. So that's question. What else is on your mind?
STERMAN: The sophistication of the attack is certainly one thing that deserves a lot of focus. What were the weapons? How many people? What were the particular targets?
INSKEEP: And these are things that we can hear the police struggling with. We hear the San Bernardino police chief pointing out that this man seems to have gone to the party. He had some kind of disagreement. He went away, which would imply, if you're trying to create a narrative - would imply some kind of snapping or instant event. But then he had tactical gear available, which suggests some kind of planning. That's part of the mystery here, I suppose.
STERMAN: Right.
INSKEEP: Is - when you study these past cases - you said you've studied many past mass shootings - do the shooters have anything in common?
STERMAN: It's very difficult to develop a profile. White men are certainly overrepresented among mass shooters, but mass shooters come from a variety of ethnicities, a variety of ages, generally male. On jihadist terrorism, it's also a diverse profile - each and every ethnicity, a variety of ages, though it tends younger now.
INSKEEP: OK. Well, David Sterman, thanks very much. We'll be hearing more from you. And again, we're continuing to follow the story of the mass shootings in San Bernardino, Calif., where 14 people were killed yesterday. Transcript provided by NPR, Copyright NPR.