Four years ago, Marquez said, he and Farook planned to toss pipe bombs into the cafeteria at Riverside Community College and then shoot people as they fled.
They also planned to throw pipe bombs on a busy section of freeway that has no exits, bringing traffic to a halt and then picking off motorists. Marquez would shoot from a nearby hillside, targeting police, as Farook fired at drivers from the road.
As part of the plan, Marquez bought two assault rifles -- in November 2011 and February 2012. He said he agreed to buy them because "Farook looked Middle Eastern."
Authorities previously said Marquez had legally purchased the guns Farook and Malik used. But the charges allege that Marquez lied by signing paperwork that said the guns were for himself or a family member.
The FBI has said Farook and Malik, 29, were radicalized before they met online in 2013, but the court documents show Farook had turned down the path to violent plots much earlier.
Marquez said he and Farook aborted their plans after authorities interrupted a terror plot in the area in November 2012 that involved four men who wanted to join either the Taliban or al-Qaida fighting U.S. forces overseas.
He said they didn't see much of each other after it unraveled, though he deepened his connection with the Farook family, marrying the Russian sister of the wife of Farook's brother last year.
Prosecutors said it was a sham marriage to help the woman obtain U.S. residency.
According to the affidavit, Marquez was paid $200 per month for the union and said his own mother and brother didn't know about it.
When his mother visited him at the hospital two days later after the shootings, her son again referred to Syed Rizwan Farook by an expletive and said he did not know "he was going to do that," Anderson said in the affidavit. Marquez also said he no longer wanted Farook as a friend.