I struggled between an idea that would basically just be a repeat of what I understood @Makemakean to have given me - that Conan Doyle was Jack the Ripper.
Wasn't
precisely what I had in mind, though of course, I recognized that it could be interpreted as such, and decided to leave that option open.
I would be surprised if Arthur Conan Doyle hasn't already
at some point come up as the favourite suspect on
some crackpot's list of who Jack the Ripper was (I mean, Queen Victoria has been fingered out as the suspect by some crackpots, and I don't mean, "She ordered the murders to be carried out", but that Queen Victoria personally donned a disguise, snuck out of Buckingham Palace in the middle of the night, went over to Whitechapel and engaged in a little serial killing on the side), and when I looked at his background--member of the Victorian upper class, trained as a medical doctor (apparently, he was very well-versed in particular when it came to sexually transmitted diseases), wrote detective fiction--it just struck me as, "Oh, you can definitely come up with a crazy theory that he was the one behind the killings!"
So, in my mind, Arthur Conan Doyle is in fact not the Ripper, it's just that the London Metropolitan Police decides to go with that theory, have him arrested, there's a highly publicized trial, in the public's mind, everyone's already convinced that Doyle is the killer, the London Met is very keen to have him convicted because this mystery has already been going on for years, they have been embarrassed and look foolish for not having been able to catch the guy, so they manufacture evidence, call in expert witnesses who perjure themselves, and so, well, poor Arthur Conan Doyle is found guilty, and hanged for the murders (even though he is innocent), and for the next hundred years or so, it is well known that "Doyle was the Ripper", and it is only in recent years that scholars and researchers look back at the investigation and start going "Wait.
Hang on!"
I invented a film!
First of all apologies to any German speakers - I did check a couple of machine translations in both directions but in my experience German->English is temperamental so it's entirely possible the other way around has created a howler. What the tagline is meant to say is : The shocking tale of a murderer! ...and his creation!
My logic for this:
Doyle's misdeeds are an international scandal, and London high society and British prestige in general is dealt a heavy blow as the horror comes to light of what one of their number did. As such the European cultural centre of gravity shifts away from London and towards the continent. This accelerates after the First World War, in which the US never intervenes and so the UK is in even worse straights while Germany is relatively better off (although I don't know if the Germany at the point that this film is made is a Kaiserreich or an alt-Weimar republic). This means that there the OTL trend of German cinema being dominant and of British and American actors working in Germany is stronger so even Hitchcock decides to work for that market.
Hence Alfred Hitchcock's Jack the Ripper (released in both German and eventually English language versions). In this film known "Heavy" Rathbone plays well within type as the cruel killer A.C Doyle aka Jack the Ripper (the original source picture I took Rathbone's image on the right from is from him as Dracula), but in a surrealist twist also plays the benevolent detective Sherlock Holmes, the increasingly physical manifestation of Doyle's guilt and conscience. Rounding out the cast are Conrad Veidt as the out of his depth Detective Abberline; Hedy Keisler as Frances Coles, the Ripper's next intended victim; and László Löwenstein (better known OTL as Peter Lorre) as George Chapman, the prime suspect in the ripper case.
Plausible? Eh. But I thought it was fun and opens up a bunch of possibilities to whoever came after me.
This is just inspired! I kind of really want to see this movie!