Interactions with the super natural are an everyday occupational occurrence by designated priests in the Catholic church around the world who have been trained in exorcism and stopping demonic oppression for centuries.
Patients are first cleared by psychiatrists and medical doctors prior to exorcism. Patients are confirmed to be possessed with evidence like speaking foreign languages the patient is not trained in (eg Latin), witnessed levitation, knowing facts of other people they first meet, or adverse reaction to prayer or holy water the patient cannot directly observe. 
Each exorcism has been approved by a bishop and the actual exorcism has multiple witnesses including family members of the patient or from the church.
See the following video interviews of priests for more details: