WASHINGTON — On the day she and her husband killed 14 people and wounded 21 others in San Bernardino, California, a woman pledged allegiance to the Islamic State in a Facebook post, officials said Friday, as the FBI announced that it was treating the massacre as an act of terrorism.
"The investigation so far has developed indications of radicalization by the killers, and of potential inspiration by foreign terrorist organizations," the FBI director, James B. Comey, said at a news conference here. But he said that investigators had not found evidence that the killers were part of a larger group or terrorist cell. The couple died in a shootout with the police on Wednesday.
"There's no indication that they are part of a network," he said.
The woman, Tashfeen Malik, declared allegiance to the Islamic State on Facebook at roughly the time of the shooting on Wednesday, according to a Facebook spokesman. At a news conference in San Bernardino, David Bowdich, the FBI assistant director in charge of the Los Angeles office, said he was aware of the post, which was taken down by Facebook on Wednesday, but he would not elaborate.
"There's a number of pieces of evidence which has essentially pushed us off the cliff to say we are considering this an act of terrorism," he said.
The attack could prove to be the deadliest Islamic State-inspired attack on American soil. Al-Qaida and other groups have carried out — or inspired — lethal assaults in the United States, but the Islamic State, which has a base of operations in Syria and Iraq, and carried out the attack on Paris that killed 130 people last month, has turned into a leading terrorism threat with spreading influence around the world.
What began as a local police response to gunfire in San Bernardino turned into a global investigation into the deadliest terrorist assault in the United States since the Sept. 11, 2001, attacks, an inquiry being headed by the FBI and stretching from California to Saudi Arabia and Pakistan. It is the nation's worst mass shooting in almost three years, since the slaughter at an elementary school in Newtown, Connecticut.
Early this year, the Islamic State shifted tactics, and instead of just trying to persuade followers to travel to Syria to join the group, it began calling on sympathizers in the West to commit acts of violence at home. The FBI has refocused its resources on that threat of so-called homegrown, self-radicalized extremists who might be inspired by Islamic State propaganda. Even before the Paris attacks, the bureau had heavy surveillance on at least three dozen people who the authorities feared might commit violence in the Islamic State's name.
The exact motives of Malik, 29, and her husband Syed Rizwan Farook, 28, remain unknown, and law enforcement officials say the couple had not been suspected of posing a danger. But after two days of insisting that terrorism was just one of many possibilities, the FBI's statements on that prospect grew much stronger on Friday. Officials pointed to evidence like the Facebook post, and what they described as a bomb-making workshop at the couple's home, where they found 12 completed pipe bombs and a stockpile of thousands of rounds of ammunition. Officials say that weaponry could indicate that the couple were planning more attacks.
Among the components investigators seized from the couple's house were items common to the manufacture of pipe bombs but also "miniature Christmas tree lamps." A recent issue of Inspire, an online magazine published by an arm of al-Qaida, included an article, "Designing a Timed Hand Grenade," with step-by-step instructions for making a delayed igniter with a Christmas tree lamp.
Investigators have also found evidence that in their final days, Farook and Malik tried to erase their electronic footprints, another sign of premeditation. They destroyed several electronic devices, including two smashed cellphones found in a trash can near their home, and erased emails, officials said.
When they were killed, Malik had what investigators believe might have been a "burner phone," meant to be used for a short time and discarded, with no social media apps or other identifying information on it. Despite their efforts, the couple's computers, phones and other electronics provide the best hope for reconstructing their communications and motives.
"We are going through a very large volume of electronic evidence," Comey said. "This is electronic evidence that these killers tried to destroy and tried to conceal from us."
On Wednesday morning, law enforcement officials say, Farook and Malik walked into a conference center at the Inland Regional Center, a social services center, and gunned down people at a combination training session and holiday lunch held by the county health department. Most of the victims were co-workers of Farook, who worked for the department as a health inspector. The couple wore masks and military-style vests, carried assault rifles and semiautomatic handguns, and left behind a bomb that failed to explode.
Law enforcement officials have noted that the case defies typical patterns for mass shootings or terrorist attacks. "A number of things in this case don't make sense," Comey said.
The Facebook posting provides one of the first significant clues to the role that Malik played in the attacks.
She was born in Pakistan, according to officials there, who added that intelligence officials were in the area Friday, searching for her relatives. Those officials, and Mustafa H. Kuko, director of the Islamic Center of Riverside, which Farook attended for a few years, said the family moved when she was a child to Saudi Arabia, and she grew up mostly in that country.
"They were living in Saudi Arabia, but they were Pakistanis," Kuko said. "They had been in Saudi Arabia for a long time. She grew up in the city of Jiddah."
U.S. officials have not confirmed that, but a person close to the Saudi government confirmed that Malik had spent time in Saudi Arabia over the years, staying with her father there. That person said Saudi intelligence agencies had no information that she had any ties to militant groups, and that she was not on any terrorism watch lists.
Malik returned to Pakistan for college, graduating in 2012 with a degree in pharmacy from Bahauddin Zakariya University in Multan, a major city in Punjab. Pakistani officials consider the area a center of support for extremist jihadist groups, including Lashkar-e-Taiba. A Pakistani intelligence official, speaking on the condition of anonymity to discuss a continuing investigation, said security officials were looking into Malik's time in Pakistan, as well as travel there by Farook.
Farook was a U.S. citizen, born in Illinois, whose parents were from Pakistan, and he earned a degree in environmental health from California State University, San Bernardino, in 2010. Officials said that not only had he never been a criminal suspect, but that he was also never mentioned by anyone interviewed by the FBI.
The bureau has uncovered evidence that he had contact, a few years ago, with five peoples whom the FBI had investigated, but not charged, on suspicion of links to terrorism. Comey said the FBI was re-examining those contacts, but he added, "I would urge you not to make too much of that."
Farook had posted profiles on Muslim dating websites, and the family's lawyers said the couple met online. American and Saudi officials have confirmed that he spent more than a week in Saudi Arabia in July 2014, and returned with Malik, flying from Jiddah to Chicago, via London. She traveled on a Pakistani passport and an American K-1 visa, the type that allows people to come to the country to marry U.S. citizens.
Farook applied for a permanent resident green card for Malik on Sept. 20, 2014, and she was granted a conditional green card in July 2015. As a routine matter, to obtain the green card the couple had to prove that their marriage was legitimate, and Malik had to pass criminal and national security background checks that used FBI and Department of Homeland Security databases.
In a news conference Friday afternoon, two lawyers for the Farook family said the couple's family were shocked by the massacre. One of the lawyers, David Chesley, also questioned whether the Facebook post was actually by Malik.
"We all want an answer," Chesley said. "We all are angry. We're all frustrated. We're all sad. We want justice. But unfortunately some things in life aren't as clear cut as that."
Chesley said Farook's mother, who lived with the couple, "stayed to herself" upstairs and was "not aware of what was taking place in the rest of the house." Law enforcement officials said the couple turned part of the house into a bomb-making factory. Chesley added that just before the massacre, Farook told his mother that he was taking Malik to the doctor and then left their 6-month-old daughter in her care. The mother has been interviewed by investigators for seven hours, the lawyer said. And the baby is with child protective services.
A second lawyer, Mohammad Abuershaid, described Malik as a "caring" and "soft-spoken" housewife who spoke Urdu and broken English. She prayed five times a day, he said, and did not drive. He added that male relatives of Farook had never seen her face because she always kept it covered in their presence.
"She was a very, very private person," Abuershaid said. "She kept herself pretty isolated."
The two assault rifles the attackers used, variants of the .223-caliber AR-15 rifle, both having been illegally modified in an effort to make them more lethal, said Meredith Davis, a special agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives in Los Angeles. One had been altered to allow a larger magazine than the 10-round maximum allowed under California law, and someone had made an unsuccessful attempt to convert the other from semiautomatic to a fully automatic machine gun.
The bureau has stated that all of the couple's guns were originally bought legally. Farook was the original purchaser of the two 9-millimeter handguns. The original buyer of the assault rifles was a person who had been interviewed officials said, and is not considered a suspect; it was not clear how Farook and Malik obtained them, or whether that transaction was legal.
After searching the couple's town house, the FBI left behind a long list of items it had confiscated. Reporters were able to see the list when the landlord opened the home to them. It included a .22-caliber rifle purchased by Farook, boxes of ammunition, holsters, a cellphone SIM card, a laptop, a wireless router, and a variety of tools and hardware.
The Islamic State has not released an official statement on the San Bernardino attack, but the Amaq News Agency, which intelligence officials believe is run by Islamic State supporters, released a statement claiming that the killings had been carried out by "supporters of the Islamic State," according to a translation provided by the SITE Intelligence Group.