Farook, 28, a public health inspector, and his wife, Tashfeen Malik, 29, used the guns to ambush his colleagues Dec. 2 at what was supposed to be a festive annual meeting of county employees, killing 14 people and wounding 21.
The FBI has labeled the killings a terrorist attack and investigators are also trying to determine if Farook had abandoned plans to launch an attack in 2012, according to two people familiar with the investigation who were not authorized to discuss the matter publicly and spoke on condition of anonymity.
Risch said Marquez and Farook "were plotting an actual attack" that year, including purchasing weapons, but became apprehensive and shelved the plan because of law enforcement activity and arrests in the area.
Marquez, whose security guard license in California expired last year, had worked at Wal-Mart since May, but has since been fired, spokesman Brian Nick said.
Viviana Ramirez, 23, a fellow student with Marquez at Riverside Community College, told the Los Angeles Times they bonded over a mutual desire to join the military.
Raheel Farook is a Navy veteran, serving from 2003 to 2007 and earning the Global War on Terrorism Expeditionary Medal and the Global War on Terrorism Service Medal, among other awards.