Well - unfortuntely - that is what I read about being often the case. It seems that when a person meets an untimely death - sometimes - the spirit of the dead person remains in or near the location where they died. I don't know why and I don't delve into the "spiritual" realm - outside of the Christian faith. HOWEVER - I do know the personal reports that have been given me of such events - the one by my nephew - cannot be disputed. He is not a liar. He also was not drunk (DOES NOT DRINK ALCOHOLIC BEVERAGES)....and he is of very sound mind. This young man will always know he was visited by a genuine "ghost" or "spirit" of a dead man. No one will be able to convince him that such "things" cannot be.
Fortunately, he has not had the experience of your Aunt in that he has been able to revisit that same house without being bothered by the ghost - as long as he does not sleep in that basement bed!!!!! (He will NEVER do that again, I have been told).
By the way - did you read the stories here on FR of the "sightings" made of the "ghosts" of the passengers on Flight 93 near the crash site in Pennsylvania???? I'll try to find those stories.