Weird Tales vol. 14, no. 5 (November 1929)
I can't quite figure out if the knife-wielding guy, presumably the titular gray killer, is wearing Roman-influenced clothing or medical scrubs. And is the victim tied down or just twined with a couple of ribbons? She could make more of an effort to save herself is all I'm saying.
Original magazine: https://archive.org/details/WeirdTalesV14N05192911Ifcsas