Premise: William Friedkin (born August 29, 1935) is an American film director, producer and screenwriter best known for directing "The French Connection" in 1971 and "The Exorcist" in 1973; for the former, he won the Academy Award for Best Director. Some of his other films include "Sorcerer", "Cruising", "To Live and Die in L.A.", "Jade", "Rules of Engagement", "The Hunted", "Bug", and "Killer Joe".
Hypothesis: William Friedkin had help writing from his brother.