You've been investigating a complicated murder case. The poor black boy was literally crucified on a pair of oars, attaching the head of a statue of Christ to him, which is truly terrifying. That's why you were referred to one of the patients, who claimed that he killed that boy and committed several other homicides. And now? Well, you were sitting in his room, or rather in his cell, and you listened to his passionate chatter, bordering on a crazy mantra.
"Well, there I was, so awfully dead in that electric chair. I didn't like it. Would you? It's upsetting! There was still so much killing to do, and there I was, in the void, without a body. But then along came, well, you know, my friend. One of them. Those others over there. The cruel ones... the Master. And he thought my work should continue, but, in this body. In this body in particular, in fact. Oooh, let's call it revenge. A certain matter of an exorcism, I think, in which your friend Father Karras expelled certain parties from the body of a child. Certain parties were not pleased, to say the least. To say the very least. And so, my friend, the Master, he devised this petty scheme as a way of getting back, of creating a stumbling block, a scandal, a horror to the eyes of all men seeking faith, using the body of this saintly priest as an instrument of, well you know my work. But the main thing is the torment of your friend Father Karras, AS HE WATCHES WHILE I RIP! AND CUT! AND MUTILATE THE INNOCENT! HIS FRIENDS, AND AGAIN AND AGAIN, AND ON AND ON! HE'S INSIDE WITH US! HE WILL NEVER GET AWAY! HIS PAIN WON'T END!... Oh... Gracious me. Was I raving? Please forgive me. I'm mad."
And then he just shut up and stared at you as if nothing had happened. Surprisingly, this patient is really very similar to your late friend, Father Karas, maybe he's telling the truth?
"Detective...Tell everyone that I'm a gemini killer."
He purred, fidgeting in his straitjacket. And those frighteningly penetrating, predatory eyes were completely unsuited to the kind Eyes that your late friend possessed.
"Maybe you'll die next.. Who knows?"