A relative of one of the San Bernardino shooters described his brother-in-law as "a bad person" who committed "a personal act" that is not tied to Islam.

The mass shooting occurred on Dec. 2 when Syed Rizwan Farook and his wife, Tashfeen Malik, opened fire at the Inland Regional Center during a Christmas party, killing 14 people and wounding 21 others. Following the massacre, Farhan Khan, who is married to Farook's sister, condemned the shooting and insisted that Farook was "a bad person," not a Muslim extremist in an interview with NBC News.

During the interview, Farook admitted that he had "no idea" what incited his brother-in-law's rampage, adding that he and his wife were "a happy couple" who loved their newborn daughter.

Khan also expressed outraged at the egregious act.

"What's the outcome?" Khan asked. "You left your six-month-old daughter ... in this life. Some people cannot have kids. God gave you a gift of a daughter. And you left that kid behind. What ... what did you achieve?"

He said Farook, who was born in Chicago to Pakistani parents, was not a political person, nor did he show any signs that he and his wife were harboring four firearms and bombs for a planned attack.

"I wish we could have ... some slightest idea," Khan said.

NBC News reported Thursday that Farook appeared to have been radicalized and had been in contact with people in the Los Angeles area who have expressed jihadi-oriented views, according to authorities. Intelligence sources also said the gunman was in touch with people of interest overseas.

However, Khan described the 28-year-old gunman as "a good religious person ... just like normal anybody would be," but insisted: "He was not radical."

He added: "It's his stupid action, nothing to do with religion at all. It's always going to be a question ... you know, why he did something like that. A normal person living with my family. Why would he do something like that?

"Did somebody brainwash him? Something snap him? What -- did he have -- a fight at work? And I'm waiting ... to hear, like, you know, what really happened," he questioned. "God knows. I have no idea. And I really want to know what made him do something horrible like that."