Back in the day, illustrators used to hire photographers and models to stage scenes from their assignments that the artists would then use as reference for their illustrations. This is how it was done for editorial illustration, advertisements and book covers. This practice is still in place today when realistic illustration is needed, but less so, as illustration has gravitated away from life-like rendering.
The illustrator was able to pull a lot of information from these photo sessions: poses, proportion, expression, light source, drape of material, etc.. The stand-in props—paper bags, cardboard tubes—would later be replaced by whatever they were there to represent—cereal boxes, rifles—culled from other source material.
Found these looking through an old box of stuff and can't for the life of me remember where I got them. I like how they exist in their own right, melodramatic poses in humble surroundings. Kind of Lynch-ian and, in a weird way, probably more realistic than the final illustrations. Or maybe that's just me.