A minor entry in the series, but perhaps better for not being as ambitious. It’s pretty easy to figure things out along the same lines that Maigret does.
And what we’re left with is another ending where justice is not so much denied as evaded, at least for a time. The killer walking free is pretty transgressive for a genre work, but despite avoiding a pat ending it’s not a very credible story and we never have any sense what’s making the tramp tick. I think he just wanted out of his marriage and found the most drastic solution imaginable.
Taking another step back, I read it as a parable, with the tramp being a holy man sent to point the moral, which is that final judgment belongs to God. “What’s impossible is to judge,” is all he’ll say. This fits with Simenon’s motto “Understand and judge not.” Not that I think Simenon always held to this, or that it’s the kind of attitude a detective chief inspector should adopt. Justice, at least of the human variety, requires judgment on someone’s part.