We had a poaching "ring" get busted in my area a few years ago. They were spotlighting the deer at night and shooting the big bucks, then after a day or two would come back to where they shot it and collect their "bounty". That sounds an awful lot like what you have going on up there, its just too dangerous for them to shoot and collect the deer in the same night (in case someone heard the shots). Hope they catch whoever is doing it, I know how it feels to lose a 3 year old investment like a 150 class buck...