Some horror movies/stories are based on true crimes (some are purely fiction). We all know this. Sometimes the movie is just based on some fact. However, let's look at Amityville Horror. There are two separate incidents here: the murder in 1974, then the paranormal activity in '75.
The house has been drastically changed, but still... would you live there?
This is the updated house: http://www.zillow.com/homedetails/108-Ocean-Ave-Amityville-NY-11701/32596605_zpid/ 
It really does look different, but I'm not sure I'd want all that bad juju. LOL