Tashfeen Malik, the female suspect in the San Bernardino, California, shooting rampage, had expressed support for the Islamic State terrorist group and its leader, Abu Bakr al-Baghdadi, in a social media post, according to two U.S. officials.

While there was no indication yet that the extremist group, also known as ISIL or ISIS, directed the massacre in California that left 14 people dead, the posting represents the strongest link yet that the killings may have been rooted, at least partially, in terrorism.

The officials, who are not authorized to comment, said the post pledging support to al-Baghdadi, was made under another name than Malik, but they declined to comment on when the message was posted — before or after the shooting at the Inland Regional Center. The Associated Press reports that Malik made the posting on Facebook using an alias, then deleted the postings.

Syed Rizwan Farook is pictured in his California driver's license, in this undated handout provided by the California Department of Motor Vehicles, December 3, 2015. Farook, one of the alleged shooters in the California rampage that left 14 dead, visited Saudi Arabia in the summer of 2014, the Saudi Embassy in Washington said on Thursday. REUTERS/California Department of Motor Vehicles/Handout ATTENTION EDITORS - FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS

Al-Baghdadi, 44, became leader of the Al-Qaeda-affiliated group, Al-Qaeda in Iraq, in 2010. The group later spread into parts of Syria and in 2014 declared itself a caliphate, under the name Islamic State, with al-Baghdadi as the leader, or caliph.

The latest developments come investigators delve into past travel, contacts and communications by Malik and her husband, Syed Rizwan Farook, for clues to the murder spree that left 14 people dead, family members say they are shocked and saw no sign that the American-born county health worker had been radicalized.

Related: Terrorists’ Baby, American Victims

A search of a residential townhouse rented by the suspects turned up a staggering arsenal of firearms, thousands of rounds of ammunition, a dozen pipe bombs and a virtual bomb-making factory, police say.

A number of electronic devices, including cellphones and a hard drive, linked to the suspects were believed to have been intentionally damaged in an attempt to thwart investigators from tracking their communications, a law enforcement official said. The official said an undisclosed number of devices were taken to the FBI laboratory in Virginia where analysts were attempting to salvage the information histories on the devices.

“Clearly they were equipped and they could have done another attack.”

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Farook had attended a holiday party Wednesday at the Inland Regional Center then left briefly, returning with his wife to open fire on the group of friends and co-workers. They wore masks and tactical clothing and carried hundreds of rounds of ammunition. The pair also left a primitive pipe bomb,which did not detonate, before returning to their rental house and its stockpile of weapons.

“Clearly they were equipped, and they could have done another attack,” San Bernardino Police Chief Jarrod Burguan said Thursday. “We intercepted them before that happened, obviously.”

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Investigators are examining evidence from three locations: the Inland Regional Center, where the killings occurred; the rented townhouse in nearby Redlands; and the rented black SUV in which the couple was fleeing when they were intercepted and killed in a gun battle with police.

Federal, state and local investigators are particularly focused on the confiscated electronic devices to find out with whom the couple may have been in contact. The New York Times reports that Farook was deleting information from electronic devices at least one day before the attack, indicating it was planned in advance and may not have come in response to any argument or slight during the holiday party.

The U.S.-born Farook worked as an environmental health specialist for San Bernardino County for five years, conducting health inspections. Farook’s co-workers describe him as pleasant, but none of the colleagues contacted remember a lot about him.

Malik, 27, was born in Pakistan, entering the U.S. on a fiancée visa in 2014, the FBI says. The pair apparently met online, while she was living abroad.

Federal officials note that Farook had visited Saudi Arabia several times, including a trip in 2013 for the annual hajj, or pilgrimage, to Mecca that all Muslims are expected to complete at least once.

If he had become radicalized, his own family didn’t appear to detect it.

Farook’s brother-in-law, Farhan Kahn, expressed shock at the killings, calling the Farook he knew a “good religious person, just like a normal, anybody would be.”

Asked by NBC News if Farook was someone who had been radicalized, he says, “Not the person I know. He was not radical.”

He calls Farook simply a “bad person” for the attack, but says he has “no idea” what prompted it. Nor does Farook’s sister Saira Khan.

“I can never imagine my brother or my sister-in-law doing something like this. Especially because they were happily married, they had a beautiful 6-month-old daughter,” Khan, who is married to Farhan Khan, told CBS News.

“It’s just mind-boggling why they would do something like this.”

When CBS reporter David Begnaud noted that people can’t fathom how a couple could drop off their infant in the morning then go out and commit murder, Saira responded, “Yeah, we can’t either.”

“It makes us very upset and angry that how could you leave a 6-month-old daughter,” Farhan added. “And he put us in this predicament,” Saira said.

Authorities have been careful not to speculate as to whether the attack, which also left 21 people injured, was a terrorist act until the investigation is complete.

“We do not yet know the motive; we cannot rule anything out at this point,” said David Bowdich, the assistant F.B.I. director in charge of the Los Angeles office.

“We don’t know if this was the intended target or there was something that triggered him to do this immediately,” Bowdich said.

Farook and his wife lived with Farook’s mother at a different location, and lawyers for the family tell CNN that the family didn’t know anything about Farook’s deadly stockpile of ammunition.

The family was “completely shocked” to find out about Farook’s involvement in the massacre, David S. Chesley, an attorney for Farook’s family, told CNN.

He said family members had never seen Farook with any of the weapons found at the townhouse.

“They haven’t seen him with them, the pipe bomb, no one had ever seen him use or have anything like that,” Chesley said.

Nor did anyone in the family think that Farook had any kind of training for such an assault.

“This person was not aggressive,” Chesley said.

Christian Nwadike, a colleague who worked beside Farook for almost four years, told CBS News that Farook was different after he returned from Saudi Arabia, where he went on a pilgrimage.

“Do you believe that he was radicalized?” Begnaud asked him.

“Yes, by the wife, I think he married a terrorist,” Nwadike said.

“He married a terrorist?”

“Yes, he was set up through that marriage,” Nwadike told CBS News.

This article originally appeared in Religion News Service and USA Today with contributions from Kevin Johnson.