Do most mystery writers know the end of their story before they begin the writing stage or is the story organic and the end comes to them during the writing?

I wrote and sold four mystery novels without outlining. Of the four, in only one did I know from the beginning who did it. The other three just sort of evolved as I wrote. I read somewhere that Rex Stout, author of the Nero Wolfe novels, never outlined and had no idea who did it until the end. But I get the impression that the majority of mystery writers outline in some way or another, or at least decide in advance who did it. It’s very strange — I’ve also written several screenplays, and I almost always make some sort of outline, what happens in act one, act two, and act three. But for some reason I absolutely cannot outline a mystery novel.