Even geometry—the staircase itself—is something that finds echoes in giallo filone.
So, my question: are there any notable, earlier, examples of a similar fedora–gloves–raincoat device—particularly in a similar murder-mystery? Maybe in the context of an Edgar Wallace adaptation?
I believe Hitchcock's The Lodger features a similar motif, but not in a way that feels as giallo-esque as it does in The Spiral Staircase. Basically, what earlier titles could also be said to provide a template for the giallo filone?