Responding to a question from KPCC, a lead FBI investigator on the San Bernardino shooting said agents were looking into whether the 12 pipe bombs discovered in a Redlands home were based on designs from Al Qaeda’s "Inspire" magazine.
"We knew that question would come up," said Los Angeles Field Office Assistant Director David Bowdich. "We’re looking into it as we speak."
The bombs were discovered in a home linked to Syed Rizwan Farook and Tashfeen Malik, who officials say killed 14 and wounded 21 at a San Bernardino social services center on Wednesday.
In its first issue published more than five years ago, the English-language magazine featured an article titled “How To Make A Bomb In The Kitchen Of Your Mom.” That same article was cited as the blueprint for the improvised bombs used by Dzhokhar and Tamerlan Tsarnaev in the 2013 Boston Marathon bombings.
The article gives detailed instructions on how to build an improvised explosive device using components readily available at grocery and hardware stores. While the Tsarnaevs chose pressure-cookers as the container for their bombs, Farook and Malik chose sealed pipes to enclose their bombs, law enforcement officials said.
San Bernardino police chief Jarrod Burguan revealed the discovery of the bombs during a press conference.
No details were given as to whether or how the pipe bombs were defused, but witnesses reported hearing loud bangs coming from the Redlands home during the search Wednesday night. The noises could come from tools used by bomb squad technicians to disable pipe bombs.
"We have continued collecting evidence, and are continuing to collect evidence at the multiple [crime] scenes," Bowdich said. "We are going to fly some evidence back to our laboratory in Washington D.C. today on a plane. That is because we want expeditious analysis of that evidence."
The FBI will likely take the remnants of the disabled bombs to their Terrorist Explosive Device Analytical Center in Quantico, Va., where agents can pull biometric data from parts and pieces that could show whether anyone other than the two attackers had a hand in making the bombs.
Burguan said the attackers had two assault rifles capable of firing .223-caliber ammunition, which indicates they are likely AR-15 style civilian versions of military weapons like the M-16 rifle or M-4 carbine. The chief said he did not know if the weapons were “California compliant” — a designation given to assault rifles that have certain features making them less easily used for mass shootings. Specifically, it relates to how much ammunition can be fed to the weapon at a single time and the ease with which empty ammunition magazines can be swapped out with fully-loaded ones.
Detachable AR-15 style ammunition magazines typically hold 30 rounds of .223-caliber ammunition, but in California those magazines must be limited to hold only 10 rounds.
Also, typical AR-15s have a large ‘magazine release button’ that must be pressed in order to swap out empty magazines for full ones. In California, that button must have a feature that makes it harder to release the magazine — often called a ‘bullet button’ — in order to be legal.
But both of these restrictions can be easily circumvented.
Higher-capacity 30-round magazines can be easily purchased, even in bulk, in other states bordering California. Similarly, regular magazine release buttons can be easily purchased in many other states and can be easily swapped out using common hand tools.
Chief Burguan also reported that a large amount of ammunition was recovered on the attackers and also in their home. About 1,600 rifle and pistol rounds were found on their bodies after they’d been killed, and police found an additional 2,500 .223-cal rounds for their assault rifles and 2,000 9-mm pistol rounds in the Redlands home.
Correction: An earlier version of this story misspelled the name of Los Angeles Field Office Assistant Director David Bowdich. KPCC regrets the error.