Very interesting. I will have to look into that. My primary research area is Medieval Church history so there I have a rather big interest in demonology and exorcism and my interest carries over into modern demonology.
I am currently researching a possible book idea on serial killers (who became Christians) and their views on demon possession.
I believe there is a difference between demonic influence and that of possession. Either one you step close to I think one needs a great measure of the Lords Spirit to battle. But equally and more complicated is when they mask as an angel of light...much more difficult to discern if you're not tight with God.
There was a priest or pastor working with some tribal people where there was a great deal of demon possession. While working with a man the Priest/Pastor told the demon that he no longer had control because Christ had defeated him at the Cross. The demon laughed and cackled and mocked at the Pastor/Priest telling him he was wrong that he was not defeated at the Cross. The Priest/Pastor said you are a defeated foe but if not at the cross then where? The demon said the forces of darkness were defeated in the desert... (when Jesus was tempted)
Later the Priest/Pastor thought much on why the dessert? Then it dawned on him had Christ succumbed in the dessert...there would never have been a crucified Christ.