@Blashyrkh: If I remember correctly, there is no story behind it. They just found the picture inside some abandoned house or something, and thought it would make a cool record cover. I might be wrong, though.
It could be that Bent based the last verse of the title track on the picture. The father, the wife, the girlchild are all on the cover, while the one holding the knife is the shadow… Or I'm over-analyzing out of my mind :lol: