The exorcism was completed in St. Louis, but the boy lived in Cottage City, MD, just across the DC line, right along the Anacostia River with Bladensburg on the other side.
That has always intrigued me, because Catholic University is less than three miles away. This was not a case of Father O'Gullible in the back of beyond dealing with something way above his pay grade. It happened next door to Catholic Central, USA.
The boy's family was Lutheran, and his dad was a federal employee. When the boy began to act strangely -- and got suspended from Bladensburg Jr. High for his behavior -- they consulted with the family doctor and their pastor. I don't know how many doctors they saw, but eventually the pastor referred the case to the local Catholic priest in that parish. This has always struck me as highly un-Lutheranlike behavior: "Hey, we've got a tough case. Let's call in the Catholics." My best guess is that the Lutheran pastor and Catholic priest were good buddies, and he brought in his friend. Anyhow, the priest escalated the case ... and the bishop had a formidable array of top Catholic experts just up the road. Who was consulted?
The boy was eventually admitted to the Georgetown University Hospital, so he was seen by the Georgetown mental health guys looking for organic causes, the shrinks looking for the whatevers for which they couldn't find an organic cause, and the attending priests. That whole team ultimately decided that an exorcism was warranted. It was begun in the Georgetown University Hospital and ended when the boy yanked a steel spring out of his hospital bedframe and stabbed a priest.
The boy's mother then took her son to St. Louis, where she had family, and the process was repeated at St. Louis University. That meant another archdiocese, another bishop, another set of doctors, shrinks and priests ... so there was now a Team A and a Team B ... and Team B also recommended an exorcism. So what, exactly, was everyone seeing?
Iirc, the boy was 13 when it started and 14 when the exorcism was completed. A LOT of expert adult eyeballs were on him, so if he was faking, he was one of the all-time great fakers. But medical and church records would be sealed unless he agreed to release them, and the boy, then man, involved was never willing to cooperate with investigators. He had no further symptoms after the exorcism was completed, went on to a long and apparently uneventful career as a federal employee, and just passed away a few years ago.
I have no idea what records may be left, but perhaps they can be unsealed at some point.
William Peter Blatty was an undergraduate at Georgetown University when the exorcism began in DC. News of the exorcism somehow got into the newspapers. Blatty didn't make anything of it at the time, but he went on to become a writer, and he returned to the subject many years later. His novel was wildly sensationalized, as was the movie -- but yes, they were based on a real exorcism.
Exorcism director William Friedkin went on to film an actual exorcism in Italy by Father Amorth—A little known film called “The Devil and Father Amorth” 2018 Weird stuff indeed. But if Jesus was able to cast out demons and gave the disciples the same power/s to do as such—then evil from time to time burrows into the human like a bot fly larvae with the same effects.