It's a pretty well known thing that Sir Arthur Conan Doyle wasn't tremendously fond of the guy that made him famous. We also know what Doyle did to Sherlock Holmes after he'd plowed through a couple of dozen short stories at a rate of one a month: The death story.
Doyle didn't seem to want to spend any more time with Sherlock Holmes than he had to, and you can plainly see that in the hiatus between the early 1890s and the 1900s. But have you ever stopped to think about how Conan Doyle bailed out of stories before they finished on a regular basis?
Take "The Five Orange Pips," for example. A man comes to Sherlock Holmes fearing for his life.
Sherlock Holmes listens to John Openshaw's tale of a mysterious threat, does a little detectivework, and figures out where the threat is actually coming from and exactly who is behind it. John Openshaw is suddenly murdered in the course of things, and in a proper story, Sherlock Holmes would then proceed to catch the killer he has identified . . . if there was more story-time for him to do it in. But how does the tale end?
"Walp, I guess the killer got away. Oh, wait! A storm at sea sank his ship, so it's all okay and we didn't really need to do anything."
There's a whole chunk of "The Five Orange Pips" that should exist, but doesn't. Instead of Sherlock Holmes tracking down a killer and apprehending him, we get "oh, yeah, a storm finally got him." I suppose that's better than "We eventually learned that Captain Calhoun died of old age on his ranch in Texas. Go, Justice!" but not by much.
And "Five Orange Pips" isn't the rare exception. Doyle decides to shortcut endings right and left.
Sherlock and Mycroft Holmes together both fail to see the villains captured in "The Greek Interpreter." Holmes and Watson eventually get a newspaper story where two guys got stabbed in Budapest and we're left to assume that was the bad guys getting their just desserts. It's not like Sherlock Holmes didn't go to Europe on occasion for a case. It's not like he didn't have contacts in the police departments of European countries.
"The Engineer's Thumb" is even worse. "Well, those guys got away. No rumors of them dying mysteriously later or anything. Yep, just got away."
But maybe expecting a Sherlock Holmes investigation to continue until a criminal is actually caught may be to much to expect. I mean, he's there to solve the mystery, right? Mystery solved, his job is done. Sure, maybe a snake or dog or some quicksand might take out the criminal, but I can't help but feel like someone was taking the rest of the day off.
Was it Holmes's actual style of case-ending, Watson getting bored with the writing part, or the literary agent who was trimming down Watson's accounts? I don't know, and I suppose I could look into this further, but I think I'm going to take the rest of the day off . . .