Destination America is streaming a live exorcism from the fabled "The Exorcist" house in St. Louis on the eve of Halloween. Bishop James Long will perform a minor rite of exorcism. (Destination America)

All reality TV producers have to prepare for worst-case scenarios when they air a live event. Jodi Tovay’s worries are a bit more unusual, because she is sending paranormal investigators into a house they believe is infested with demonic spirits.

“The worst-case scenario is that one of these entities will attach to someone,” Tovay said. “It is dangerous.”

Luckily, Tovay says, the physical symptoms are usually obvious when an evil spirit attaches itself to a person: nausea, scratches, superhuman strength. A team of paramedics will be on standby, as will police. She’s ready.

Welcome to “Exorcism: Live!” airing at 9 p.m. Friday on Destination America, a cable channel owned by Discovery Communications. The two-hour telecast tasks a clergyman, a psychic and the team from the network’s “Ghost Asylum” series to go into the spooky suburban St. Louis home that inspired “The Exorcist” book and movie. Ghost hunters insist that the house is filled with a dark, sinister energy, and “Exorcism: Live!” is determined to cleanse it.

“People have called it the biggest supernatural mystery in American history — so many tales that have come out of that house and still exist around it,” Tovay said. “So we almost had to do something.”

“The Exorcist,” William Blatty’s 1971 horror novel, was based on the real-life case of a Maryland teenager known as Roland Doe. In 1949, Doe became violently ill, screaming in languages he was never taught, and doctors couldn’t figure out what was wrong. Eventually, religious leaders decided that Doe was possessed by the Devil. Through exorcism rituals, a Catholic priest freed Doe of his demons. At the time, The Washington Post called it “perhaps one of the most remarkable experiences of its kind in recent religious history.”

Doe traveled between Maryland and St. Louis for exorcisms as doctors and members of the clergy examined him. He stayed with relatives in the house in St. Louis and underwent an exorcism on the second floor. “Ever since the attempted exorcism of Roland Doe rumors have swirled that the house is still possessed by an evil entity,” Destination America explains on its Web site.

“It’s waiting there to attack somebody else who is going to come in and let themselves open themselves up so it can attach itself to that individual in our reality,” said Nick Groff, the former star of Travel Channel’s “Ghost Adventures.” “That’s what scares me more than anything.”

Have chills yet? That’s what Destination America is counting on, even if they are of the campy variety. During the special, camera operators will squeeze into the small house with the team of paranormal experts, including psychic Chip Coffey and Bishop James Long. Six cameras throughout the house will allow viewers to watch footage online and use Twitter to alert the crew if something happens in another room.

The suburban St. Louis home that inspired "The Exorcist." A team will try to cleanse it of evil spirits Friday. (Destination America)

Chip Coffey is the psychic who recently visited the house and felt a very sinister presence. (Destination America)

The most thrilling aspect for Tovay is that this will be live. No one can accuse them of manipulating anything, she said — a criticism often leveled at paranormal shows.

“We can’t fake it on live TV. We can’t fake evidence or pump in sound effects. The drama is unfolding right in front of you,” Tovay said.

But what about the people (okay, lots of people) who believe that this is all completely made up? Long, the clergy member who will accompany the group, is used to that. He just doesn’t have time to worry about it anymore.

“I’m not here to prove that demons exist. I am here to help families who know they do,” Long said. He is the founder of the ­Kentucky-based Paranormal Clergy Institute, which assists homeowners who think that their house has a demonic infestation. This isn’t just for when things go bump in the night — this is for when people experience loud sounds in the walls, violent scratches and the desecration of religious objects. Clergy members investigate whether it’s demonic spirits or simply odd noises.

Long said he hopes the special will give hope to people suffering with infested houses, letting them know that they’re not alone.

Still, he knows there are skeptics. “I know for a fact that demonic possession exists, I know that without question,” Long said. “If I didn’t know, I would be doing something else.”

So he joined “Exorcism: Live!” and will be on hand to: (a) keep everyone as safe as possible, and (b) perform a minor rite of exorcism, trying to force the evil entity in the house to manifest itself so the team can get rid of it. Long said he had spoken to Coffey, the psychic, who checked out the house in advance to see whether it was haunted. He immediately felt something evil lurking, he said. Afterward, Coffey told the bishop, “James, this is going to be a very intense ritual.”

“Everybody will be signing a waiver, and they know the activity could be very violent — there’s no guarantee about safety,” Long said. “I can’t guarantee anyone’s safety when I walk into this place. [We’re] going against a demonic entity.”

This program is somewhat a natural progression for Destination America, which mostly airs shows such as “BBQ Pitmasters” and “BBQ Pit Wars” but also broadcasts paranormal series, such as “Ghost Stalkers,” “Ghosts in My House” and “Ghostly Encounters.”

“People are so fascinated by ghost stories,” Tovay said, citing the network’s success with shows such as “A Haunting.” “We do have lots of paranormal content. People are really interested in a good story.”

Friday’s special also will have footage of diaries from people who saw Doe’s exorcism, along with other scary anecdotes from the St. Louis house, such as the one about a local investigator who once went inside and came back out with a white cross burned onto his neck.

And don’t worry, the family that lives in the house won’t be around to see their home taken over for a live TV exorcism.

Wait, what? A family actually lives there?

Oh, yes, they do. Even Tovay, a self-described “super fan” of the “Exorcist” story, admits that she doesn’t really understand that one.

“I haven’t quite wrapped my mind around that,” Tovay admitted. “But it is a beautiful neighborhood with great schools.”

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