I'm reading through newspapers articles from some files wherein JR describes the shooting. Although he was very specific that he had shot LHO but this is how he described what he said to the police afterward:
"What are you guys all jumping on me for? Why am I here? I'm Jack Ruby. I'm not somebody that's wanted."
"They dragged me into the elevator. They brought me upstairs. They told me I had shot Oswald"
"That was the first time I realized what I had done. I said, 'My God. My God!".
It's meaningful to me that when he says he did it in the same discussion he says that they told him he did it. It's very telling. So they not only told him he did it, since he didn't remember they must have told him how he had done it. It's exactly how you suggested it occurred, that they told him.
Further inside this 192 pages of documents there is an interview with Box:
Box said, "Oswald had the bureau with him all the time except for 10 minutes. The only time you won't find an fbi agent watching him was when he came down the elevator in the police department and got shot. How many bureau men were standing in the basement waiting?"
When asked what he thinks of this Box responds, "I'll leave it to your conclusions. The more I conclude, the more paranoid I sound."
This was my response:
That's a really great find, Amy. And the most telling thing of all, in my opinion, is him saying, after he was told that he shot Oswald, "My God, My God." What a contrast to what the Dallas cops claimed he said, "I'm glad the son of a bitch is dead. I hope he dies. I did you all a favor.." Etc. How could both be true? And who are you going to believe? I'm going to believe Ruby.