A similar thing happened in Ireland about two years ago, involving two elderly sisters, and in the house where I lived in Hannover, Germany, six months after I moved out, a body (of a woman I knew to see, as she often called to my apartment to use my phone) was found--it had lain in her apartment for eight months (neighbours thought she was in hospital--she was prone to having strokes).

In Ireland one of the sisters died and her body lay in the bed for about six months while her sister slept in the next room. Again there was a mental problem. These things happen quite often (and always have, IMHO), and are not always reported.