Syed Rizwan Farook and Tashfeen Malik had been radicalized "for quite some time" and practiced shooting at a gun range days before they opened fire on a San Bernardino holiday party, authorities said Monday.
Investigators have interviewed more than 400 people since Wednesday's attack but are still trying to determine how long they plotted the massacre and what links if any they had with Islamic terrorist groups.
The FBI and other agencies are also working to assemble a profile of the couple's life and how exactly they amassed their cache of weapons, ammunition and explosives.
"We are attempting to expand that investigation out and build it and build a picture of each person, the timeline and ultimately the crimes they committed," said David Bowdich, assistant director in charge of the FBI's Los Angeles office. "That takes time. We are in Day 5."
Meanwhile, pieces of the puzzle continued to slowly emerge. John Galletta, a firearms instructor at Riverside Magnum Range in Riverside, said Monday that Farook practiced shooting with a military-style weapon, adding that an employee described him as a "normal guy."
Galletta said the company turned over surveillance footage and sign-in logs to the FBI.
Two of the guns Farook and Malik used in Wednesday's massacre — both semiautomatic rifles — had been given to the couple by a former neighbor, who was interviewed by investigators and checked himself into a mental hospital after the attacks, two law enforcement sources said.
Fallout from the attack continued to play out on the national political stage, with Republican front-runner Donald Trump calling for all Muslims to be barred from entering the United States for an indefinite period until leaders "can figure out what is going on."
The incendiary statement, coming a day after President Obama sought to reassure the nation, drew immediate condemnation from the White House and several of Trump's rivals for the
The developments came as officials described a sprawling global investigation into what drove the married couple to adopt extreme beliefs and whether they had any links to foreign terror organizations.
Bowdich cautioned that terrorists can be bred by online rhetoric and are not necessarily linked to a group.
"We are working with our foreign counterparts to determine as much as we can," he said. "It's like any other investigation, but this one is incredibly large." More than 300 pieces of evidence have been collected — some of which were sent to Washington, D.C., to be analyzed at the FBI's explosive device center. Among the items taken from the shooters' Redlands home were 19 pipes that could be converted into bombs.
The agency is also applying survey technology to the crime scene at the Inland Regional Center, where the shooting began. A reconstruction team is attempting "to ultimately paint that picture of how everything transpired that day," Bowdich said.
"Our job is to continue the investigation at breakneck speed," he added.
John D'Angelo of the Bureau of Alcohol, Tobacco, Firearms and Explosives said five guns were recovered from the shootout scene and the couple's rented two-story townhouse. Farook had legally purchased a Savage Arms .22 rifle, a Llama 9mm handgun and a Springfield Armory 9mm handgun between 2007 and 2012, D'Angelo said.
Acquaintance Enrique Marquez had given the couple the semiautomatic Smith & Wesson M&P15 and .223-caliber DPMS A-15 rifles, authorities said.
Until a few months ago, Farook and Malik lived in Riverside, next door to Marquez. Farook, observed as quiet and withdrawn, struck up a friendship with Marquez, who shared a similar interest in tinkering with cars, a neighbor recalled.
"They would spend hours and hours and hours together," said the neighbor, Rosie Aguirre. "That's the most sociable I ever saw him with anyone."
Federal authorities interviewed Marquez over the weekend, and a law enforcement official familiar with the investigation said the weapons he gave to Farook were legally purchased in 2011 and 2012. There is no paperwork of them being transferred to Farook, he said.
On Sunday, the FBI seized items from Marquez's home after having spent several hours there the day before, according to neighbors. There was no indication at the time that Marquez had any knowledge of the plot, a source said.
Authorities have said it appears Farook, 28, and Malik, 29, did a great amount of planning before the attack.
Scrubbing the backgrounds of the couple — who were killed in a shootout with police hours after their rampage — has been an international effort, with cooperation from foreign governments. In Pakistan, where Malik attended college and Farook's parents were born, the interior minister announced that an inquiry into the shooters' background had been launched. Investigators were also looking to sources in Saudi Arabia, where Malik lived as a child.
Federal investigators are trying to determine if Farook was influenced by Mohamed Abdullahi Hassan, a former Minneapolis resident known as "Mujahid Miski" who became a recruiter for Islamic State and is alleged to have encouraged the attempted attack on a cartoon contest in Garland, Texas, earlier this year. The U.S. State Department said Monday that Hassan turned himself in to authorities in Somalia, where he had been hiding.
FBI officials have said that Farook had "some contact" with someone known to the FBI in this country and also reached out digitally to at least two members of foreign terror groups, including one in Somalia, said a federal law enforcement official who is unauthorized to speak publicly on the matter.
Born in Chicago and raised in Riverside, Farook met Malik on a dating website. The couple were married last year in Islam's holy city of Mecca in Saudi Arabia, and Saudi officials confirmed that Farook spent nine days in the kingdom in the summer of 2014. The couple's daughter was born in May, according to records.
Farook's sister and mother hope to gain custody of the baby, the Council on American-Islamic Relations said in a statement. The organization said it is working to place the baby with a Muslim family as it remains in child protective services. A follow-up custody hearing has been scheduled for January.
On Monday, five days after the massacre that killed 14 and injured 21, many San Bernardino County employees returned to work. Filled with emotion, they draped arms around one another as they walked into the county buildings that had just reopened.
"The purpose of terrorism is to make ordinary people afraid to do the ordinary things that make up their lives," Supervisor Janice Rutherford said. "These were dedicated public servants. They weren't politicians, they weren't celebrities. They weren't law enforcement officers, they weren't soldiers. But they became the front line in a battle against terrorists. To honor them, to express our gratitude for their unimaginable sacrifice, we have to fight to maintain that ordinary."
About a year ago, employees of San Bernardino County's Environmental Health Services division underwent an "active-shooter training."
It was held in the very same room that would one day be a site of bloodshed and horror.
It was not clear if Farook, an environmental health specialist for the county, attended the earlier training, but some of the victims of the mass shooting were likely to have participated, said a county spokeswoman.
Staff members within Farook's division will return to work next week.
Times staff writers Paloma Esquivel, Veronica Rocha, Joseph Serna, Matt Stevens and Matt Hamilton and contributed to this report.
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