WASHINGTON — The woman who helped carry out the shooting in San Bernardino, Calif., on Wednesday had pledged allegiance to the Islamic State in a Facebook posting, according to federal law enforcement officials.

There’s 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, said the officials, who spoke on the condition of anonymity because the investigation is continuing.

“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 s

The posting had been removed from the social media site and it’s not clear when federal authorities obtained it.

In recent months, the F.B.I. has been particularly concerned about individuals inspired by the Islamic State staging attacks in the United States, law enforcement officials say. Even before the shootings and bombings in Paris last month, the agency had under heavy surveillance at least three dozen individuals who the authorities were concerned might commit violence in the group’s name.

The F.B.I. refocused its efforts on these individuals earlier this year in response to a shift in tactics by the Islamic State, law enforcement officials said. Instead of trying to persuade Americans to travel to Syria to join the Islamic State, the group began calling on its sympathizers and followers in the United States to commit acts of violence at home.

“We’ve especially focused on the portfolio of people we’re investigating for the potential of being homegrown violent extremists,” the F.B.I. director, James B. Comey, said last month at a news conference. “That is, people consuming the propaganda. So those investigations are designed to figure out where are they on the spectrum from consuming to acting.”

“Within that group we’re trying to focus on those we think might be at the highest risk of being a copycat,” Mr. Comey said, referring to those who may try to follow the attackers in Paris. “And so we are pressing additional resources, additional focus against those. That’s the dozens.”

In the days leading up to the shooting, the couple in San Bernardino took several steps to delete their electronic information, in an apparent effort to cover their tracks, officials said. Those efforts have led authorities to believe that the shooting was premeditated.

Islamic terrorists have used the oath of allegiance, called a bayat, to declare their loyalty to specific groups and leaders. To become a member of Al Qaeda, for instance, terrorists historically swore their devotion to Osama bin Laden.

As investigators search for signs of a political or religious motivation for the massacre, the discovery of Ms. 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.

Ms. Malik, 27, was born in Pakistan and traveled on a Pakistani passport, but had recently lived in Saudi Arabia. Mr. Farook, 28, was a United States citizen, born in Illinois, whose parents were from Pakistan.

Mr. Farook had posted profiles on Muslim dating websites, and apparently the couple met online. He told co-workers last year that he was traveling to Saudi Arabia to meet his bride, and both American and Saudi officials have confirmed that he spent more than a week in that country in July 2014.

Mr. Farook, was an American citizen, and he and Ms. Malik traveled to the United States together in July 2014, David Bowdich of the F.B.I. in Los Angeles said at a news conference. He said she had traveled with K-1 visa, a special visa that allows people to come to the country marry an American citizen. A couple has to marry within 90 days; after that the K-1 visa expires.

Mr. Farook applied for a permanent resident green card for Ms. Malik on Sept. 20, 2014, within the legal 90-day limit, a federal official said. She was granted a conditional green card in July 2105. As a routine matter, to obtain the green card the couple had to prove that their marriage was legitimate. Ms. Malik also had to pass criminal and national security background checks that used F.B.I. and Department of Homeland Security databases.

Courtesy: New York Times