Three days after a heavily armed Muslim couple who lived in a home investigators described as "an IED factory" burst into a Southern California office building and gunned down 14 people, the FBI finally -- and awkwardly -- acknowledged Friday that it is treating the case as an act of terrorism.

In an unusual and brief address to reporters at which Attorney General Loretta Lynch appeared and questions were not taken on camera, FBI Director James Comey affirmed the bureau's LA office's characterization earlier in the day.

"This is now a federal terrorism investigation," Comey said, alluding to evidence collected from electronic devices and reports that Syed Rizwan Farook and Tashfeen Malik may have been sympathetic to radical terrorist groups prior to the attack. After his comments, Comey asked pool reporters if they had any questions, but the pre-taped event, which was later distributed to media outlets, was cut off abruptly and no questions were permitted.

The director, a Republican appointed in 2013 and a former deputy attorney general under President George W. Bush," did not allude to the Muslim faith of suspects Syed Rizwan Farook and Tashfeen Malik. But in pronouncing it a case of terrorism, he seemed to be stating the obvious while at the same time going farther than President Obama has been willing to go and possibly hinting at some behind-the-scenes dissent. Sources told Fox News Lynch was there to "ensure [Comey] didn't take it too far" in his characterization of the attacks.

“Tashfeen remains the biggest mystery. She’s the one no one knows anything about and has little to no presence on the Internet or having interacted with others in the Muslim community.”

- Southern California Pakistani-American leader

On Thursday, in the face of mounting evidence of a terror motive, President Obama refused to rule out an office dispute as the possible motive for the attack. The equivocation stoked outrage among many of Obama's critics, who noted his insistence on labelling as "workplace violence" the 2009 Fort Hood shooting, in which a Muslim Army major killed 13 people and injured another 30 while shouting “Allahu Akbar” and his ongoing refusal to characterize acts of terror as driven by radical interpretations of Islam.  

More On This...

"If you can't come to a conclusion at this point that this was an act of terror, you should find something else to do for a living than being in law enforcement. I mean, you're a moron," former New York Mayor Rudy Giuliani, who led the city during the 9/11 attacks and their aftermath, thundered hours later on Fox News.

Then, on Friday, hours before the FBI announcement, Fox New confirmed that Malik had pledged her allegiance to ISIS as the morning attack began. She and her husband were killed hours later in a shootout with police just two miles away. Those developments confirmed the suspicions of many, and left it obvious that Malik, at least, was driven by radical Islam.

"We are investigating it as an act of terrorism, for good reason," David Bowdich, the assistant FBI director in charge of the Los Angeles office, told reporters in an afternoon news conference before his boss spoke.

Bowdich, who said neither of the two were on law enforcement's radar prior to the attack, cited several factors for the focus on terrorism, including "extensive planning" that went into the attack. The pair attempted to cover up their digital trail, damaging hard drives and other electronic devices, Bowdich said. Investigators did find two cell phones recovered from trash cans near the couple's Redlands home, and recovered evidence of communications with others who are now being investigated.

“They tried to wipe out their digital fingerprints,” he said, adding that digital communications will likely provide further substantiation of the motive, but "it's not a three-day process."

The post by Malik, in which she pledged allegiance to ISIS leader and self-proclaimed “caliph” Abu Bakr al-Baghdadi, was confirmed by Facebook official. They said she posted the pledge just before she and Farook stormed a San Bernardino party for his co-workers before escaping. The couple died hours later in a shootout with police, and in the aftermath the 29-year-old Pakistani woman has remained largely a name without a face. No confirmed pictures of her have surfaced, and few details have emerged. The aura of mystery surrounding Malik has given rise to suspicions she may have been the radicalizing force who turned Farook from an aloof county restaurant inspector into her cohort in carnage, an Islamist fanatic capable of murdering co-workers who had embraced him for years.

"Usually it's ISIS supporters trying to radicalize young girls online as they try to find new wives, but this may be the first case I know of where the opposite happened," said Ryan Mauro, a national security analyst for Clarion Project, which tracks international terrorism.

Mauro noted that Farook's older brother, who shares his name, served in the U.S. Navy, which would seem to indicate that Farook's radical leanings did not come from within his own family.

"It is possible that she radicalized him or that suspected terrorists inside America he was communicating with are responsible for the radicalization, which led him to be attracted to a more hardline Salafi girl," Mauro said.

What is known is that Malik met Farook online and that the two became engaged after Farook traveled to Saudi Arabia in September 2013. Malik applied for a K-1 visa at the American embassy in Islamabad in May, 2014 and two months later Farook again traveled to Saudi Arabia, met her there and brought her to the U.S. on a K-1 visa, a 90-day visa given to fiancés planning to marry Americans.

“Tashfeen remains the biggest mystery,” said a leader of the area’s Pakistani-American Muslim community. “She’s the one no one knows anything about and has little to no presence on the Internet or having interacted with others in the Muslim community.”

They were married on Aug. 16, 2014, in nearby Riverside County, Calif. according to their marriage license. The marriage and passage of criminal and national security background checks using FBI and Department of Homeland Security databases resulted in a conditional green card for Malik in July 2015, two months after she gave birth to their baby daughter.

Malik and Farook, an American citizen born in Chicago and raised in Southern California by parents of Pakistani descent, lived with their daughter and his mother, Rafia Farook, in a Redlands, Calif., apartment described by one investigator as an “IED factory” and ammo arsenal.

However, Farook’s mother claimed not to have suspected any potential plots or problems pertaining to her son and daughter-in-law, telling others that the weaponry didn’t raise any eyebrows as he “was always into guns” from a young age and shooting was very much a part of his life.

Attorneys representing Farook's family said at a late afternoon press conference that none of Farook's relatives had any indication he or his wife held extremist views.

Federal officials confirmed that the four guns Malik and Farook carried when they were killed in a shootout Wednesday afternoon, some three hours after storming the San Bernardino social services facility where his department was holding a holiday party, were purchased legally. Law enforcement sources told Fox News that investigators believe the couple's death prevented a second attack Wednesday, though they have not established what the target would have been. 

There have been reports Farook had ties to radicals in Pakistan and had a trip made there in recent years, but a source connected to the Pakistani Consulate in Los Angeles told FoxNews.com that he did not possess a Pakistani passport and that there is no record of him applying for a visa to travel to Pakistan through his local consulate. That did not preclude the possibility that he may have entered the country illegally or obtained a visa overseas or elsewhere.

Farook is a third-generation American from a family hailing from Karachi. Sources close to his family insisted that his marriage to Malik was not arranged. He told co-workers, who hosted a baby shower for him and his wife earlier this year, that Malik was a pharmacist. The California Board of Pharmacy has no record of her working as either a pharmacist or a pharmacist’s assistant.

Farook was a devout Muslim who prayed every day and recently memorized the Koran, according to brothers Nizaam and Rahemaan Ali, who attended Dar Al Uloom Al Islamiyah mosque in San Bernardino with Farook. Rahemaan Ali said he last saw Farook three weeks ago, when he abruptly stopped going to the mosque. Ali said Farook seemed happy and his usual self, and the brothers never saw a violent side.

"He never ever talked about killing people or discussed politics, or said that he had problems at work," Rahemaan Ali said. "He always had a smile on his face."

Prior to their marriage, Farook had multiple online dating profiles claiming he was a Sunni Muslim from a “religious but modern family” and that he was “looking for a girl who has the same outlook, wear hijab, but live life to the fullest, be my partner for snowboarding, to go out and eat with friends, go camping, working on cars with me.”

Farook was remembered as reserved by co-workers, who said he had grown his beard out in recent months – often a sign among Muslims of heightened religious devotion. He also had gotten into several heated arguments with a co-worker, Nicholas Thalasinos, about Islam. Thalasinos reportedly questioned whether Farook’s faith was truly a “religion of peace.” He was one of the 14 killed in Wednesday’s attack.

Neither Malik nor Farook had a criminal record, and the couple did not mix with the larger Pakistani-American community, and few people claim to have seen, let alone met, Malik, including neighbors. The Pakistani-American Muslim community leader, who asked that his name not be used, said the community believes is is clear that someone radicalized Farook.

“This event has shaken everyone,” said the source. “The fact that Syed and his wife seemed to be so removed from the community and no one really knows much about him or his wife at all can often be a key indicator something is wrong.”

Fox News Channel's Matthew Dean, Adam Housley and Hollie McKay contributed to this report