I was a little stressed when I heard on the radio that the FBI was going to get involved in the Las Vegas massacre. I thought, "There goes the evidence! We'll never get the truth now." Why this crime isn't purely a state jurisdictional matter I cannot say. However, I believe that there is reason to believe that powerful, dangerous forces diffused among America's elite do not want to endanger their evolving nefarious operations by allowing some state or local law officer of the Sheriff Joe Arpaio sort to expose and render to the courts for adjudication guilty parties [re Obama]. Better assassinate a patsy, send in the FBI to seize and hide any evidence which might point to sinister elites [re 9/11], and trust in the controlled, simpatico Major Media [CNN et al] to flood the citizens with disinformation pointing at the patsy and away from the Resident Evil.
There are many cameras inside and outside the Mandalay Bay Casino, as well as in adjoining hotels, and telling video must be revealing. Look for the FBI to seize all videos. However, videos that can support, or be edited to appear to support, the FBI's public testimony subsequent to its investigation may well be shown via Major Media outlets.
The only good part of this tragedy will be the fertile analysis by lay investigators shared across the Internet. By means of this collective "people's investigation," the American people will have more by which to judge the event than the Establishment's "one-armed, bushy-haired Neo-Nazi Klansman, acting as a "Lone Wolf."