TORONTO - When horror filmmaker Eli Roth set out to produce "The Last Exorcism," in theatres Friday, he knew there was no way it would provide more chills than the Oscar-winning 1973 fright fest "The Exorcist."

So he and director Daniel Stamm took on a more modest mantra: "Don't try and be scarier than 'The Exorcist.' Be the best version of whatever story you're telling," Roth said in a recent interview.

"I saw 'The Exorcist' when I was six years old and it completely traumatized me," confessed Roth, who is considered part of the "Splat Pack group" of filmmakers for writing and directing bloodbaths including "Hostel" and "Cabin Fever."

"I had never been so scared in a movie and had always wanted to be involved in making an exorcism film. But I thought: 'How can you ever make a movie scarier than The Exorcist?' And the answer is: you won't and you can't.

"But that doesn't mean you can't also make another great exorcism movie, something that's completely different."

What makes "The Last Exorcism" -- written by Huck Botko and Andrew Gurland -- unique is that it doesn't just feature a teen (Ashley Bell) being exorcised of an apparent demon.

We also meet a sly reverend (Patrick Fabian) who believes cases of alleged possession are really just examples of mental-health challenges.

With that, he sets out to perform one last exorcism in Baton Rouge, La., to expose the religious ritual as a fraud.

Using a hidden stereo system with 800 different "demon sounds" and other trickery, the preacher performs a sensational exorcism with the belief that the girl he's treating just has psychosomatic symptoms and will be cured because she believes she is.

Stamm shoots it all in a shaky, documentary-style a la "The Blair Witch Project."

Roth says he first read the screenplay four years ago and at one point considered directing it, but he stepped back because he wants to establish himself as a producer.

He was particularly interested in the material because his father was a psychiatrist/psychoanalyst and professor at Harvard University.

"He had an office at our house, so all day people were going in and out," said Roth, 38, whose acting credits include "Inglourious Basterds" and the recently released "Piranha 3D."

"My father would explain to me why they were coming and why people go to psychiatrists, but he also told stories about what it was like when he trained in Bellevue (Hospital Center) at the mental-psycho ward where people were so gone they couldn't be out in the streets but they couldn't be in prisons either. They were completely insane."

Roth also felt "The Last Exorcism" was timely given the apparent prevalence of cases of possession in today's society.

"We were financing the film in 2008, putting together the money for it, when the Pope came out with a big speech saying: 'We are opening an exorcism academy to train more exorcists,"' said Roth.

"And three years ago there were 25 sanctioned exorcists in Rome and today there are over 300.

"So that means one of two things: either the devil is on the rise or fake exorcisms are on the rise, so either way it's bad news."