The club only had five members according to the AW, and it wasn't accessible to the public. He probably thought a grave there would be least likely to be stumbled upon.
Wow...sneaky...I would have made a very bad criminal and dug a hole in the wide open, thinking OH trees and vegetation will cover it! That and already sung like a canary. I think these 3 are going to deny deny deny - even KM all the way thru long circus like trials....