Pues nada, aquí está:
Investigative journalist Mark Opsasnick investigated the case and concluded that the Mount Rainier story, as popularly held (and which Blatty used as a basis for the novel), could not be true. For one thing, the family that occupied the home at the time the alleged possession took place did not have a boy there, demon-possessed or otherwise: the occupants were childless. Long-time neighbors denied that anything horrific or supernatural had ever occurred there. There was, however, an actual exorcism done (not in Mount Rainier but in Garden City, Maryland), though virtually all of the gory and sensational details were embellished or made up. Simple spitting became Technicolor, projectile vomiting; (normal) shaking of a bed became thunderous quaking and levitation; the boy’s low growl became a gravelly, Satanic voice. And so on. Those interested in the full details can find them in articles by Opsasnick. One is «The Haunted Boy,» published in Fortean Times, Number 123, page 34; another is in Strange Magazine, 1998, Number 20. The piece is also available online at www.strangemag.com.