You heard it from Leatherface himself, a real Pro at the chainsaw game! His character Leatherface torments and chases people around with his chainsaw looking for his next kill. His "leather" face is actually made of the skin of his victims, and he is completely mute throughout all of the movies.
The Texas Chainsaw Massacre may not be based on entirely true stories, but it is still known as one of the scariest horror franchises to this day. The directors' intentional lie at the beginning that the "film you are about to see is true", was a response to being "lied to by the government about things that were going on all over the world", which at the time included Watergate, the 1973 oil crisis, and the massacres and atrocities of the Vietnam War.