WASHINGTON — The woman who carried out the San Bernardino massacre with her husband came to the U.S. last year on a special visa for fiances of U.S. citizens, raising questions about whether the process can adequately vet people who may sympathize with terrorist groups.

Authorities said Friday that Pakistani citizen Tashfeen Malik, 27, pledged allegiance to the Islamic State group and its leader under an alias account on Facebook just moments before she and her husband, Syed Farook, opened fire on a holiday banquet for his co-workers, killing 14. They later died in a gunbattle with police Wednesday.

Malik, who had been living in Pakistan and visiting family in Saudi Arabia, had passed several government background checks and entered the U.S. in July 2014 on a K-1 visa, which allowed her to travel to the U.S. and get married within 90 days of arrival.

Malik was subjected to a vetting process the U.S. government describes as vigorous — including in-person interviews, fingerprints, checks against U.S. terrorists watch lists and reviews of her family members, travel history and places where she lived and worked. The process was began when she applied for a visa to move to the United States and marry Farook, a 28-year-old Pakistani-American restaurant health inspector for the county who was raised in Southern California.

Foreigners applying from countries recognized as home to Islamic extremists, such as Pakistan, undergo additional scrutiny before the State Department and Homeland Security Department approve permission for a K-1 visa.

It was not immediately clear what information Malik provided as a part of the background check by the State Department and U.S. Citizenship and Immigration Services or when she became radicalized.

“This is not a visa that someone would use because it is easy to get into the US, because there are more background checks on this type of visa than just about anything else,” said Palma Yanni, a Washington-based attorney who has processed dozens of K-1 visas. “But fingerprints and biometrics and names aren’t going to tell you what is in somebody’s head unless they somewhere have taken some action.”

The government’s apparent failure to detect Malik’s alleged sympathies before the shootings will likely have implications on the debate over the Obama administration’s plans to accept Syrian refugees. Attorneys representing Farook’s family deny that he or his wife had extremist views.

On Friday, ABC News reported that the address in her Pakistani hometown that Malik listed on her visa application does not exist. In response to a question about the ABC report, State Department spokesman Mark Toner said: “We are actively reviewing all of the information provided in the visa application and sharing it with our interagency partners as it relates to the investigation.”

The vetting process for refugees is similar, though not identical, to the one for fiance-visa applicants.

“Uncle Sam just looks on as an approving Cupid and doesn’t pay as much attention as he should to the issuance of these visas,” said David North, a senior fellow with the Center for Immigration Studies, which advocates for stricter immigration policies.