Pre-planned, and yet the couple involved was living the American Dream by all accounts. Ayed Farook inspected retaurants for the county health department. Religious but not overt about it. Brought a wife back from Saudi Arabia. Tumultuous home life as a child. Said to have gotten along with workers but came to an office party, argued, left and returned in ten minutes dressed for killing.
A sweep of his computer, phone records and social media will reveal much.