The frame style is almost certainly P35/Hi-Power, but the slide contours do not match up with any P35/HP or clone that I am aware of.
- The slide is wider at the base than the top.
- The side of the slide is not flat, it shows a radius/rounded area just above the bottom edge, in addition to the normal radius on the top surface.
- The slide, despite its apparent wider bottom edge, does not cover the width of the frame above the trigger guard area, nor does it cover the top rectangular opening in the thicker part of the frame above the grip mounting area (if the slide is not mounted to the frame, or some/all of the frame rails are missing, and the slide is just balanced on top of the frame for photographic purposes, then this observation is invalid and is withdrawn).
Based on the above points, I'd guess that it may be a P35/HP frame with the slide from another handgun placed on top. This might also explain the missing barrel, because while you might be able to force an empty slide from another gun onto a P35/HP frame, having the barrel in the slide could greatly complicate matters, or even prevent the slide's installation.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)