Exorcism in light of the recent Maori exorcism case [Updated]

How to tell if a person is possessed, in the words of the Vatican's Chief Exorcist:

"It is not easy. There are many grades of possession. The Devil does not like to be seen, so there are people who are possessed who manage to conceal it. There are other cases where the person possessed is in acute physical pain, such agony that they cannot move."

"It is essential not to confuse demonic possession with ordinary illness. The symptoms of possession often include violent headaches and stomach cramps, but you must always go to the doctor before you go to the exorcist. I have people come to me who are not possessed at all. They are suffering from epilepsy or schizophrenia or other mental problems. Of the thousands of patients I have seen, only a hundred or so have been truly possessed."

How can you tell?

"By their aversion to the sacrament and all things sacred. If blessed they become furious. If confronted with the crucifix, they are subdued."

But couldn't an hysteric imitate the symptoms?

"We can sort out the phoney ones. We look into their eyes. As part of the exorcism, at specific times during the prayers, holding two fingers on the patient's eyes we raise the eyelids. Almost always, in cases of evil presence, the eyes look completely white. Even with the help of both hands, we can barely discern whether the pupils are towards the top or the bottom of the eye. If the pupils are looking up, the demons in possession are scorpions. If looking down, they are serpents."

Related Link: An Interview With Father Gabriele Amorth: The Church's Leading Exorcist

UPDATE: It has been assumed by at least one person that via this post that I have endorsed the "exorcism" of the Maori woman who died. Let me be absolutely clear here - I have not endorsed that "exorcism". I don't even think the woman was possessed or cursed, as it takes far more that stealing something to curse someone. I put up this post only to show what a real exorcist looks for in possessions.