Wouldn't Johnny Ola's men been the obvious suspects? Since it was Roth that wanted Mike killed, and Ola was his Sicilian messenger boy, doesn't it make sense that Ola's men did it?
I agree with you. These were probably Johnny's men and Fredo probably helped them make their way onto the compound w/o being accounted for by security.)
I don't think they were "snuck" into the compound. If you remember they accompanied Johnny Ola into see Mike (I always liked his entrance, the door opened, and he announced Johnnnny Olaaaa sort of like how Ed McMahon would have announced him
). Mike and everyone else knew they were there. Remember Mike offered to feed Johnny's men.
