"They were actually radicalized before they started courting or dating each other online, and online as early as the end of 2013, they were talking to each other about jihad and martyrdom before they became engaged and then married and lived together in the United States," FBI Director James Comey said at a Senate oversight hearing.
"We also believe they were inspired by foreign terrorist organizations," he added. "We're working very hard to understand exactly their association and the source of their inspiration."
Investigators are also looking at whether Syed Rizwan Farook
and Tashfeen Malik
had "other plans either for that date (last week) or earlier," Comey said.
When asked by the Senate panel whether a terrorist operative or group arranged the couple's marriage, Comey stated: "I don't know the answer to that yet."
When pressed whether such an arranged marriage would be a "game changer" in the FBI investigation, Comey added, "It would be very, very important thing to know."
New details emerge on visa interview
If Malik had already radicalized years ago, how did she get the go-ahead to immigrate to the United States in 2014?
A senior State Department official told CNN on Wednesday that Malik was not asked about jihadist leanings when a U.S. consular official interviewed her in Pakistan for her fiancee visa application last year. That's because no red flags were found in the Department of Homeland Security application that was submitted and checked before the interview, the official said.
The consular officer who did the interview reported that Malik was able to answer enough questions about Farook to prove that she knew him well and that they had a personal relationship, a main focus of the consular interview process, according to two senior State Department officials.
After the interview, Malik passed two other security database checks before her visa was adjudicated. Records show the visa was decided on the day after the interview: May 23, 2014. Malik came to the United States on July 27 of that year. According to California marriage records, she married Farook just one month later.
Past plot with former neighbor?
As federal authorities attempt to piece together the circumstances surrounding the San Bernardino attack, they've been questioning Enrique Marquez, a former neighbor and friend of Farook.
Marquez bought two AR-15s years ago that were among the weapons Farook and his wife used in the shooting. He's also told investigators that he plotted another attack in California with Farook in 2012
, U.S. officials said. The pair abruptly abandoned their plan, according to the account Marquez gave investigators, because they were spooked by unrelated FBI arrests of four people charged with attempting to travel abroad to carry out jihad.
Marquez has told investigators he didn't know about the plans for the San Bernardino shooting attack. He has not been charged with a crime.
Officials caution that Marquez's claim of a 2012 attack could turn out to be false and an attempt to deflect his role in helping buy weapons that Farook later used in the San Bernardino attack.
Combing online communications
Investigators are still trying to piece together profiles of the Farook and Malik, who killed 14 people at the Inland Regional Center in San Bernardino last week and died the same day in a gun battle with police. They're also working to pinpoint whether anyone in the United States or abroad helped finance and shape the plot.
The FBI has found online communications between the two killers from late 2013, before they began dating, indicating the two discussing jihad, Comey said.
Investigators have found data on a tablet computer and other cell phones at the couple's home. The FBI also has the benefits of data from U.S. intelligence agencies that collect foreign communications and from service providers for the accounts they used to communicate.
The final post on a Facebook page believed to be associated with Malik used the word "we" and pledged allegiance to ISIS, an indication, a U.S. official said, that it was a statement on behalf of both killers.
Investigators are working to determine whether the pair ever met or took orders from ISIS
leaders, or if anyone outside the United States had a hand in or knew of their plans. Officials say it's possible the husband and wife did everything, from becoming radicalized to planning and executing the attack, on their own.