My father knew Fr. Hughes, the local parish priest in Mt. Rainier, who was very young, and had no experience doing exorcisms. Archbishop O’Boyle, also young and naïve, gave him permission to perform an exorcism, which was very imprudent. Hughes is the priest who was gouged in the leg by the boy, using a bed spring. He nearly bled to death, and limped the rest of his life. He described being at the house; dinner was on the table, steaming hot, and before anyone went into the dining room, the table rose in the air and tipped upside down.
You say that both Fr. Hughes and Archbishop O'Boyle were young and naive. I am perfectly prepared to accept that. But I wonder if the machinery of the Church was seriously engaged. As the protocol on exorcisms works today (in my layman's understanding), medical and psychiatric professionals would first try to account for any non-supernatural explanations. There would be independent checks and balances. As I said before, I wonder what the staff at the GU Hospital had to say (assuming they were asked). And after the kid was taken to St. Louis, the evaluation was repeated there.
There are more loose ends than answers, but your father's account is fascinating.