If the Church decides it has a truly possessed individual on its hands -- one that requires an exorcism -- the next step is to appoint an exorcist to the case. This is often the same priest who performed the investigation, but not always.
Casting out the devil is not part of a typical priest's daily duties. Most priests have never performed an exorcism. But some have.
Official numbers are hard to come by, but "American Exorcism" reports that in 1996, the Catholic Church appointed 10 priests to the position of exorcist in the United States, bringing the total number to 11. Cuneo estimates the worldwide number at somewhere between 150 and 300, while other reports claim there are 300 to 400 official exorcists in Italy alone [ref]. There are also priests who are not official exorcists but claim to have permission from their local bishop to perform exorcisms at their discretion. The exorcism ritual has made a big comeback from being nearly extinct throughout most of the 20th century.
Traditionally, Catholic exorcists undergo very little specific training to aid them in their job. While they learn a great deal about the devil and the risks and manifestations of evil, exorcism itself is not a specialized area of study in seminary school. What they know, they know from their experience in the role of priest and from the Roman Catholic rite of exorcism, which is the official document detailing the prayers and steps of an exorcism. Things are starting to change, though. Official exorcists of the Catholic Church formed their own organization in 1992. The International Association of Exorcists holds biannual meetings in Rome and sends out a quarterly newsletter to its members. In the newsletter, exorcists tell of particularly difficult or interesting cases and swap "tricks of the trade" (Cuneo, 266). In addition, in 2005, Rome's Regina Apostolorum Pontifical Academy (a university connected to the Vatican) started offering a class on exorcism.
Once the Church appoints one of its official exorcists to perform the ritual, the next step is to get the devil to leave the person's body.