While we strive to investigate and find proof of the paranormal, proof of an existence beyond our life here, we also try to rationalize why those that have trancended this life but refuse to leave for whatever reason and have stayed. Some of them may not know they are dead and  they stay around to be with loved ones. They might have some personal business and remain thinking they can complete whatever it is that keeps them here. So many reasons can be argued, there are the skeptics that do not believe that there is an afterlife or that spirits and ghosts dont exist.