IMO, hindsight is giving a clarity that's just not reasonable to expect. Now every little thing this shitbag did is a "missed sign". But for neighbors and co-workers that doesn't seem to be the case. For all they knew, he was being deployed, worried he wasn't going to survive, and decided to give stuff away. And I think we've all been handed religious literature.
I know it's early, but from what I've been hearing so far, most people took him for a good, quiet, decent officer who wasn't thrilled with the war. I know several officers and even more enlisted who aren't fond of the war. That doesn't mean they're going on killing sprees. And everytime they do something weird or say something I don't agree with, doesn't justify a full investigation into their lives.
Acting as though "somebody" should have put all the pieces together is just unreasonable.
Maybe we'll get lucky and one of the nurses will accidentally give him a lethal dose of medication.