Not sure what you mean?
First off, going by what Ive read / experienced.. theres differences between ghost, demons, poltergeists..etc.
Ghost is a lost soul that is usually oblivious... living in a sort of dream world that repeats over and over again. Possibly some sort of static echo in time...
Then there are spirits that are actually conscience and responsive... but pretty much harmless. Most spirits have no ability to do anything physical. Only other humans sensitive and open can act as a gateway, giving them enough energy/permission to transfer thoughts, a feint voice, and once in a rare while... to move something light such as rolling a ball. Doing anything physical usually draining them to the point of not being able to do it again for several days or much longer afterwords. (which is why activity usually isnt consecutive)
Poltergeist are said to be angered souls, bent on causing harm. They can toss objects across the room. However, its my belief that these are not one spirit... but instead, a team of spirits acting together to make physical things possible. Even so, I believe these things still need a gateway person to get power in this realm. Fear is sort of an enabler... because the person who fears, sort of allows them to have power by default. They will believe that the spirits have more power/control than them... and it only gets worse with time.
Demons - Supposedly non-human type spirits. But Im not so certain about this. These often do their best to take possession of a living body. Usually a weak willed person, who is an easy target. Altering their moods, and forcing their control little by little.
If anyone was killed by a poltergeist... It would probably be ruled as an accident or seizure. (falling / pushed down stairs) If it was a Demon, they would probably make the person commit suicide.
Its pretty rare that any occurrences happen to begin with, because most spirits move on to the next realms... where as only a few bitter / confused souls stay behind. Even then, there usually has to be a gateway person to enable them. Most people dont believe in such things... and so these things cant exists in their reality (cant manifest). But fear sometimes gets the better of even the non-believers, and allows a doorway to open.
The people who have experienced things tend not to tell others, unless they are very good friends, and very confident there will be no spilling of the details. Ive met many people who are trustworthy, who have seen and experiences paranormal things on several occasions.
The worst being my own mother, when she was a child. Some of those stories confirmed by my moms sister. They lived in a very messed up house as children.
To date, Ive seen a translucent ghost from 12 ft away in a well lit hallway... as well as 2 large shadow figures running past me in mid-afternoon, in the sun lit appt.