The woman who carried out the Southern California massacre with her husband immigrated to the U.S. legally last year on a special visa for fiances of U.S. citizens.

Authorities say 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 with her family in Saudi Arabia and Pakistan, 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.

Foreigners applying from countries recognized as home to Islamic extremists, such as Pakistan, undergo additional scrutiny.