Ralph Sarchie hasn't been on coasttocoastam.com since 2004.
http://www.amazon.com/Deliver-Us-Evil-Investigates-Supernatural/dp/1250059496/ctoc
A lot of times movies will take dramatic licence to a story that has some factual connections.
http://theweek.com/article/index/264245/the-real-story-behind-deliver-us-from-evil
Also, a lot of paranormal phenomenon is difficult, if not impossible to prove.
http://www.dailymail.co.uk/news/article-2682409/NYPD-cop-turned-demonologist-believes-demonic-possessions-rise.html
Such is the case of a house in Amityville, NY.
http://jfvrinfo.blogspot.ca/2011/11/amityville-enigma.html
http://literaryfictions.com/2014/07/28/know-the-devil-by-his-name