I believe there is a point in some people's physical lives when their soul no longer has any interest in staying in a tortured body and leaves before the physical death of that person. The body that remains is certainly vulnerable to spirits invited or not. I do no know if a soul would have wanted to have come back to my granfather's body but it may have comforted those watching his body die if they could have been removed from off of his body? The spirit that visited me that night's face was like my grandfather's but it was burning red and as large as the room. An intention left undone, searching for peace.