Psychopath, Islamic sleeper, government conspiracy, Las Vegas finances ?? Something has to be the answer. His finances need to be checked, when and from whom; travel itineraries; computer needs to be dissected; contact list from cellphone; etc. And if the police and government continue to shrug their shoulders, then the people should sue the hotel and Las Vegas for negligence in security.
Didn't anyone enter the room for cleaning during this guy's stay at the hotel ? And they saw nothing? Also extremely planned operation - cameras to watch hallway, massive amount of guns and ammo, perfect locale and view (must have asked for room months in advance).