Why bury a body in shackles? They must have been pretty expensive items at the time and it's not like the headless corpse was going to escape!
LOL.
That is interesting. Chains were to restrain the body so it didn't come back, and the head was removed so even if the body came back it wouldn't be able to navigate accurately. There was a lot going on with bodies, they didn't cease all function and they didn't have the modern juridical State to declare them dead.