Doctor Richard Gallagher is a board-certified psychiatrist and professor at New York Medical College who has been working with priests for 25 years.
He has interviewed thousands of people thought to have been possessed, confirming hundreds of actual demonic possessions.
Gallagher, who is Catholic, is also an adviser for the International Association of Exorcists. He is publishing a book, Demonic Foes, A Psychiatrist Investigates Demonic Possession in the Modern United States, about his experiences.
The Demonic activity continues during and after this interview.