It couldn't have been a ghost
SPOILERS ***** SPOILERS ***** SPOILERS
Another post critisized this movie with some clarity. It followed the, "Blair Witch" hit movie formula which was novel and uniquely successful in its time over ten years ago, but now is dated. In other words, had this movie appeared around that time period or soon after, it might have stood more on its own.
Still there's some entertainment value to this movie.
My only criticism comes from the observations of paranormal researchers, ghost hunters, secular and religious demonologists, who seem to agree on one hypothesis.
Human ghosts (souls) exist in actual hauntings, but human ghosts are near powerless, if not completely powerless. Bereft of their physical bodies, human ghosts have no telekinetic powers. One paranormal researcher feels that maybe at most, a human ghost can move about 10 pounds in weight, if even that.
Now, demons and devils, that's another matter. All the above people agree that demons and devils (higher levels of demons) exist, do haunt places and people, and more, possess actual, non-visible physical power. That is, the invisible demon can move a refrigerator across the room. Demons and devils were created as non-corporeal entities with actual powers of their own.
If you believe in all of this, then there was no 'Richard Speck' malevolent ghost in 100 Street, even though it wouldn't be unexpected if it was hanging around. But all Speck's ghost could do is frighten people, feeding off their fear. It would take an actual demon to do the physical attacks. The rape of Sarah would have to have been demonic in origin, although, lacking an actual physical phallus, such an attack would be more, 'simulated', even though the terror inflicted would be the same. By the way, that's one of the most effective realistic special effects since the 1983 sci-fi flick, The Entity.