The couple authorities say carried out the San Bernardino massacre last week had trained for the carnage, including partaking in target practice only days before the Wednesday attack, according to the FBI.
So far there's no evidence they were helped, said David Bowdich, assistant director in charge of the FBI's Los Angeles area office, "but we will leave no stone unturned."
Both 28-year-old Syed Farook and 27-year-old wife Tashfeen Malik were "radicalized" and had prepared for the attack that took the lives of 14 and injured 21 others at the Inland Regional Center in San Bernardino.
"We have learned both subjects were radicalized and for some time," Bowdich told reporters during a news conference today.
Farook had attended a workplace event at the facility that morning and returned with Malik to carry out the shootings, authorities said. They had two Smith & Wesson 556 assault rifles that had been modified as well as two handguns, authorities said.
The FBI said the weapons were purchased legally in California between 2007 and 2012. Neighbor Enrique Marquez purchased the rifles, authorities said, but he's not suspected of helping the couple plan the carnage.
Farook and Malik had been married two years.
He was born here. She was a Pakistani brought here from Saudi Arabia on a so-called fiancee visa, according to reports. Both reportedly professed allegiance to the Islamic State recently.
"Right now our major concern ... is determining how those firearms ... got from Marquez to Farook and Malik," said John D'Angelo, assistant special agent in charge of the L.A. office of the Bureau of Alcohol, Tobacco & Firearms.
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The couple appeared to be ready for a bloodbath, the FBI indicated.
"We do have evidence that both of these subjects participated in target practice ... within days of this event," Bowdich said.
On Wednesday afternoon the pair died in a gun battle with cops. The couple had 1,600 rounds of ammunition at the ready, and one officer sustained a non-life-threatening injury.