Government Missed Red Flags re Naval Yard Shooter

How did the Navy Yard gunman pass at least two background checks? Why wasn't he prosecuted for prior criminal acts? Why wasn't his clearance pulled.?  Why wasn't security seriously beefed up at every military facility after the Fort Hood mass murders?  Why weren't there armed guards all-over the Navy Yard?  Why didn't some of the staff there carry sidearms? (I know the Obama administration doesn't like guns and self-defense, but this is inexcusable)The ball was dropped by governments and innocent people paid the price.  Anyone who thinks government has enough care, smarts or resources to protect them 24/7 everywhere, and thus people don't need guns for defensive purposes, is living in a dream world.