The wife of the Pakistani-American man who together carried out the deadly California shooting, pledged allegiance to Islamic State (Daesh) leader Abu Bakr al-Baghdadi on Facebook and had radicalised her husband before the attack that killed 14 people, US investigators said on Friday.
Officals said that as the attack in San Bernardino was happening, 27-year-old female shooter Tashfeen Malik posted a pledge of allegiance to IS leader al-Baghdadi on Facebook, three US officials familiar with the probe told CNN.
They said Malik's post was made on an account with a different name, one US official said. The officials did not explain how they knew Malik made the post.
A law enforcement official said it appeared that Wednesday's attack - which left 14 people dead and 21 wounded before the two attackers, Malik and her husband, 28-year-old Syed Rizwan Farook, were killed in a shootout with police -- may have been inspired by IS terror group. But none of the officials said that IS directed or ordered the attack.
"This is looking more and more like self-radicalisation," a law enforcement official said.
Another official said authorities haven't ruled out that others may have influenced this radical view. In addition, the law enforcement source said investigators have a greater focus on whether the shooting occurred after a workplace issue with religion.
Malik may have radicalised her husband investigators said a day after the heavily-armed couple opened indiscriminate fire during a party at a social service centre for people with disabilities in San Bernardino, California.
Law enforcement sources said that there was a "very strong" possibility that Malik functioned as Farook's terror trainer and may have even put together pipe bombs found by authorities at the various crime scenes.
Investigators also believe that the parents of a 6- month-old daughter, had planned a second attack after the shooting at the social service centre that killed 14 people and injured 21 others.
Law enforcement sources said that investigators believe the couple's death in police action prevented a second attack on Wednesday, though they have not established what the target would have been.
They point not only to the sheer amount of weaponry left unused, but also to the fact that the couple's rented SUV was due to be returned on Thursday.
Little is known about Malik's background prior to her meeting Farook. However, a US official said that the two met and became engaged after Farook traveled to Saudi Arabia in September 2013.
Malik, a Pakistani citizen, applied for a K-1 visa at the American embassy in Islamabad in May 2014 and Farook travelled to Saudi Arabia that July to bring her to the US.
They were married on August 16, 2014, in nearby Riverside County, California, according to their marriage license.
Investigators believe that on at least one of those trips to Saudi Arabia, one or both members of the couple contacted suspected al-Qaeda terrorists. The exact nature of that contact was not immediately clear, the Fox News report said.
Officials said that Malik underwent and passed a Department of Homeland Security counter-terrorism screening as part of the process of getting the K-1 visa. The visa would have been effective for 90 days, after which Malik would have had to apply for green card status through the Department of Homeland Security as the wife of an American.
As part of the complex investigation, authorities were trying to piece together a money trail that would have enabled the suspects to acquire over USD 30,000 worth of guns and explosives.
Public records show that Farook earned nearly USD 51,000 per year as an employee of the San Bernardino County Department of Public Health, making it unlikely he could have afforded such an arsenal out of his own pocket. There is no evidence that Malik had a job.