Mystery Mailer turns a window inside out

I received this card in a plain envelope that was marked with the URL to a website that does not exist.  The card is an image of a painting, apparently from a book or magazine. I don't recognize the work, but it appears to depict a peremptory execution by a squad of soldiers or gendarmes, possibly Russian. A window has been cut through this image, revealing a nude figure, another painting again from a printed book or magazine. The figure appears to float over the image of the spldiers, but, in fact, lies physically beneath that piece. The collage is a disturbing image, to say the least.

The back of the card is coated with a solid blue layer of glossy ink? (above, left). It isn't readily obvious, but the blue field obscures some text. Using contrast controls on my scanner the text becomes partially legible. It appears to be an Italian text discussing art, or a specific painting, that is.

So the mytsery is this: who or what is P-ARS, the "name" on the card as well as the dysfunctional URL on the envelope. Any insights will be welcomed!