What happened to transform a trained pharmacist and a county health inspector into terrorists, and when did they take that dark turn?

Officials say it could have been years before last week’s deadly attack in San Bernardino, California.

Investigators believe shooter Syed Rizwan Farook may have been plotting an earlier attack in California with someone else, two U.S. officials told CNN on Tuesday. One of the officials said the two conspired in 2012 and a specific target was considered. The pair “got spooked” and decided not to go through with the earlier attack after a round of terror-related arrests in the area, an official said.