Joe Bob Briggs has an excellent retrospective column on the film The Texas Chainsaw Massacre.
Many people believed, and still believe, that the movie is entirely true, in part because of its effective cinema verit351 documentary style. In this respect, Tobe Hooper anticipated "The Blair Witch Project" by 26 years, and he did it without the advantage of cheap video. Far from being an artless "shaky-cam" documentary, "Chain Saw" is Hitchcockian in its complex editing: in a film less than 90 minutes long, there are a total of 868 edits, some of them as short as four frames, or one-sixth of a second. No wonder it shocked the world. Forry Ackerman, the writer and film historian who has watched every horror film since 1922, said even his jaded eyes believed the actors were real people. "It's a watershed work," he told Brad Shellady in the video documentary "Texas Chainsaw Massacre: A Family Portrait." "It brought a new dimension of reality to horror films."
And that reality, in 1974, was not entirely welcome.