San Bernardino shooting : Female Suspect Made Facebook Pledge to ISIS

The report quoted officials as saying that there is  no evidence the group directed the woman, Tashfeen Malik, and her husband Syed Rizwan Farook, to launch the attacks, which killed 14 and wounded 21.

"At this point we believe they were more self-radicalized and inspired by the group than actually told to do the shooting," one of the officials was quoted as saying.

As investigators search for signs of a political or religious motivation for the massacre, the discovery of Malik's Facebook posting has forced them to consider whether any radical impetus for it came from her more than from the husband, or from both. The couple were killed in a shootout with the police after the attack.

FBI officials came up with no hits when they searched agency databases for Farook's name, according to law enforcement officials. That is significant because it meant that not only was Farook never the focus of an investigation, he was also never mentioned by anyone else interviewed by the FBI, even in unrelated cases.

The bureau, however, has uncovered evidence that Farook had contact with five individuals on whom the FBI had previously opened investigations for possible terrorist activities, law enforcement officials said. It was not clear, however, how significant the contacts were.

One individual contacted was associated with the al-Shabab, the Islamist militant group in Somalia. Another was associated with the Nusra Front, the Qaeda wing in Syria. None of the other three were tied to the Islamic State or core al-Qaida. All five inquiries was closed, and the contacts were made a few years ago, not recently, the authorities were quoted as saying.