A special blu-ray edition of the hit horror film The Exorcist is coming out on Tuesday, October 8, 2013 to celebrate the 40th anniversary of the film based on a novel of the same name by Peter Blatty who was inspired by real events.

The film tells the story of the possession of Regan MacNeil and the exorcism by Father Merrin and Father Karras. The Exorcist director William Friedkin has written a book titled “The Friedkin Connection: A Memoir” about the 1973 hit horror film. An excerpt is included in the anniversary edition of the film.

Blatty first learned about the 1949 exorcism of a Maryland boy in a New Testament class in White-Gravenor Hall at Georgetown and that inspired Blatty to write about the possession of Regan, named under the pseudonym of Roland Doe. Roland’s parents began to notice strange occurrences such as his bed shaking and furniture moving across the room. He was admitted to the Georgetown University Hospital, but the doctors found nothing wrong with his health.

Roland’s parents met with Catholic priest Father Albert Hughes, who believed Roland was possessed and got permission from the Archbishop of Washington D.C. to begin the rite of exorcism. Relocated in Saint Louis, Missouri, nine priests participated in Roland’s exorcism over several weeks.

One of the priests, Father Bowdern, kept a diary of the exorcism. The Daily Mail reprinted his entry, “Even while the institution of the Blessed Sacrament was explained to (Roland) his body was badly scratched and branded.” He went on, “The word ‘HELLO’ was printed on his chest and thigh. Upon the explanation of the Apostles becoming priests and receiving Our Lord at the Last Supper, scratches appeared from (Roland) hips to his ankles in heavy lines, seemingly as a protest to Holy Communion.”

After his exorcism, Roland married, had children and retired in suburban Maryland after working for the US government. He never spoke publicly about the exorcism although his case did appear on the front page of the Washington Post while Blatty was a student at Georgetown.

Friedkin and Blatty, who are both Georgetown alums, shot many of the film’s scenes on Georgetown’s campus. He told the Democrat and Chronicle, “The film is in many ways a hymn to Georgetown.”

The steps in the film’s climactic scene were shot at Georgetown and the crew built an extension with a false front. Before their appearance in The Exorcist, Friedkin remembers they were known as the “Hitchcock steps.” He said, “They evoked something spooky and suspenseful.”

The mystery of faith was important to Blatty when he wrote The Exorcist. The questions of faith were important to Friedkin too. “It was not a promotion of the Catholic Church but definitely a story about the power of Christ and the mystery of faith that continues to this day.” He continued, “I’m flattered when people admire it, but when they call it a horror that’s not how I feel about it.”

The trailer for the film is below. Readers are cautioned that it is very disturbing.