Got news today suggested the guard was part of the plot.
I have a couple of problems with that theory, which as I understand it is that the guard offed Paddock, shot himself to appear a victim and then greeted police at the elevators.
First problem is that I gather the guard was actually on another floor beforehand talking to people who pointed him up to where the sound of the shooting had been coming from. Seems not to fit.
Second, I don't think Paddock would have allowed the accomplice to put a revolver in Paddock's mouth, he would have resisted and the accomplice would have had to shoot him differently.