Enrique Marquez, the dude who either gave/sold the guns to Farook is his childhood friend, but not only that, he's married to the sister of Farooks brothers wife.
He also just admitted him and Farook were planning an attack back in 2012.
Farooks mother lived with them at the house, as well. She's being question as to how she never knew what they were doing in the garage. (bomb making, guns, bullets etc)
If, if, there is a third suspect and he did get away, I wouldn't be surprised if it was that childhood friend Enrique. He immediately went to a mental health facility, after the attacks, and was placed on a 72-hour hold.