What are exorcisms, why does the Catholic Church do them, who was Anneliese Michel and what’s the story behind The Exorcist?

HOLLYWOOD has dramatised the chilling and horrific religious ceremony of exorcisms - but real life versions often make international headlines.

Here we take a look at why the Catholic Church performs them.

What is an exorcism?

The idea that demons exist and can possess people is one of the most widely-held religious beliefs in the world.

Most religions claim humans can be invaded by demonic spirits, and offer exorcisms to cast out them out.

The Vatican first issued official guidelines on exorcism in 1614 and revised them in 1999.

The changes state that “the person who claims to be possessed must be evaluated by doctors to rule out a mental or physical illness".

Along with a handful of Vatican-sanctioned exorcists, there are hundreds of self-styled ones around the world.

Catholic Church law requires that every diocese has at least one specially-trained priest who can perform exorcisms, although the Vatican says demonic possession is very rare and the majority of cases turn out to be people suffering from mental illnesses.

In past centuries, epilepsy, schizophrenia, Tourette's syndrome and similar conditions were mistaken for demonic possession.

Why are exorcisms performed?

The Church lists symptoms of demonic invasion as a loss of appetite, unnatural body postures and a change in the person's face and voice, as well as predicting future events and a cold feeling in the room.

Other tell-tale signs include a person losing control and lashing out, an intense hatred toward religion or antipathy towards entering a church, speaking Jesus' name or hearing scripture.

Most reported cases do not require an exorcism because twentieth-century Catholic officials regard genuine demonic possession as an extremely rare phenomenon.

Often someone will just need medical help.

How does an exorcism work?

In the Catholic church, the exorcist must be an ordained priest.

They recite prayers and use religious materials such as a crucifix to invoke God - in the Name of Jesus - to intervene with the exorcism.

The possessed person may be restrained for their own protection.

The Catholic Priest recites certain prayers such as the Our Father, Hail Mary, and the Athanasian Creed.

It is important for the exorcist to finish the prayer otherwise the demon will pursue him.

Sometimes exorcisms can take days, weeks or months of constant prayer.

In 1928, Capuchin friar and Catholic priest Theophilus Riesinger performed a 23-day exorcism on an Iowa women who cried “My Jesus! Mercy! Praised be Jesus Christ!” when the demons were finally said to have been driven out.

Exorcisms also take place in other faiths with an imam performing one on an Islamic woman believed to be carrying an evil spirit.

Was The Exorcist based on a true story?

The film has shocked and horrified audiences since its release in 1973 but most don't realise The Exorcist was actually based on true events.

In Missouri in 1949, a 14-year-old boy was subject to a months-long exorcism performed by Jesuit priests.

The teenager, who was given the pseudonym Roland Doe to protect his identity, was introduced to a Ouija board by his spiritualist aunt Harriet.

The boy's parents began to notice strange occurrences such as his bed shaking, furniture moving across the room and scratching noises coming from inside the walls.

After Harriet's death, the boy's parents met with Father Albert Hughes, the Roman Catholic priest at Saint James Parish, near their Maryland home.

Father Hughes said he believed the boy was possessed and sought permission from the Archbishop of Washington DC to begin the rite of exorcism.

Roland's parents relocated him to a relative's home in Saint Louis, Missouri, where over the course of several weeks as many as nine Jesuit priests, including Father Bowdern participated in the boy's exorcism.

Another of them, Father Raymond Bishop, kept a diary of those encounters.

During the exorcism, the boy allegedly slipped one of his hands out of the restraints, broke a bedspring from under the mattress and used it as a weapon to slash the priest's arm.

On a second exorcism, both priests visited Roland and observed a shaking bed, flying objects, the boy speaking in a guttural voice, and exhibiting an aversion to anything sacred.

After the exorcisms, Roland apparently married, raised children and maintained a long and productive career with the US government before retiring, reportedly to suburban Maryland. He has never spoken publicly about the case.

Analysts of Roland Doe's case in later years believe he likely suffered from a mental health issue such as schizophrenia or Tourette's Syndrome that was far less understood in the 1940s.

Who was Anneliese Michel?

In the 1970s, Anneliese Michel, a 23-year-old student from Klingenberg, after years of suffering convulsions began experiencing devilish hallucinations while praying.

By 1973, she was suffering severe depression, considered suicide and had voices in her head telling her she was damned.

She would perform 600 genuflections a day, eventually rupturing her knee ligaments.

The deeply religious student crawled under a table, barking like a dog for two days. She ate spiders, coal and bit the head off a dead bird.

She even licked her own urine off the floor and could be heard through the walls screaming for hours.

In 1975, her request for an exorcism was granted and was performed by Fr Arnold Renz and Pastor Ernst Alt.

The priests identified several demons, including Lucifer, Judas Iscariot, Nero, Cain and Adolf Hitler, who spoke with the correct Austrian inflections.

Haunting voice recordings were made of Anneliese gurgling and talking about the horrors of Hell through one of the six demons she was possessed by.

By the spring of 1976, Anneliese was suffering from pneumonia and emaciation and she died on July 1.

Her parents, Anna and Josef, were put on trial for their daughter's murder alongside the two priests who performed the exorcisms.

All were found guilty of negligent homicide by allowing her to starve and given suspended six-month prison sentences and three years' probation.

The horrific ordeal was the basis for 2005 film The Exorcism of Emily Rose starring Jennifer Carpenter.