TWO days after 14 people were killed and more than 20 injured when two shooters opened fire in San Bernardino, federal investigators have said they were investigating the "horrific act as an act of terrorism".
David Bowdich, assistant director of the FBI's Los Angeles office, said the amount of ammunition recovered, the degree of planning involved and the "digital footprint" left by the husband and wife suspects, had led them to that conclusion.
A day earlier, both Mr Bowditch and President Barack Obama, said investigators had not yet concluded whether the attack was terrorism, work-related violence or else a combination of the two.
But on Friday lunchtime, Mr Bowditch told reporters: "There are a number of pieces of evidence to push us off the cliff to say we are looking at this as an act of terrorism."
Earlier, it was reported that Ms Malik had pledged allegiance to Isis leader Abu Bakr al-Baghdadi.
A number of US media outlets said that according to US officials, Ms Malik, the wife of Mr Rizwan, pledged allegiance to al-Baghdadi in a posting on Facebook under an account that used a different name.
The posting, since deleted, was made under an alias account at 11am on Wednesday - the same time that first emergency calls came in about the shooting.
The Associated Press said Facebook discovered the account on Thursday. It removed the profile from public view and reported its contents to law enforcement officials.
The fact that Ms Malik apparently made a posting on Facebook had added to suspicions and claims that a "deeper terror matrix" may lie behind the shooting attack.
In the days leading up to the shooting, the couple took several steps to delete their electronic information, in an apparent effort to cover their tracks. Those efforts were among the clues that led authorities to believe that the shooting was premeditated.
Mr Bowdich said investigators were aware of the reported Facebook posting. Yet he said it was unclear yet whether the couple had received any sort of instructions from extremist overseas. He said investigators were looking into the hard drives from the couple's computers and phones.
One official told the New York Times: "At this point we believe they were more self-radicalised and inspired by the group than actually told to do the shooting."
Mr Rizwan, was born in Illinois and raised in Southern California, and worked worked for the San Bernardino County health department.
He met his wife online and brought her to the US from Saudi Arabia in the summer of 2014 on a K-1 visa, which designated her his fiancée, and required a rigorous background check.
He applied for a permanent resident green card for her in September 2014, and she was granted a conditional card last July.
Ms Malik's family is originally from Pakistan and the intelligence services in Islamabad have reportedly been in touch with in touch with her family.
The Isis-affiliated news agency, Aamaq, said the two shooters were supporters" of the Islamic State group, but it stopped short of claiming responsibility for the attack.
Mr Farook, 28, and Ms Malik, 27, lived with his mother in Redlands, about five miles from where the attack took place. It was with his mother that they left their six-month-year child before setting off on Wednesday morning.
It was also in Redlands on Wednesday afternoon, that police encountered the couple in their black SUV, and engaging in a gun-battle in which more than 450 bullets were exchanged and in which the couple died.
Laywer David Chelsey, who represents the family of the couple, told CNN he believed it was impossible that the 90-lb Ms Malik could have been involved in the shooting.
"There are a lot of disconnects and there is a lot of unknowns and there is a lot of things that quite frankly don't add up or seem implausible," he said.