Missing Man Found Dead in Abandoned House with Symbols on Walls

I'm not that anon, but I also used to search for people. At my first job I worked in civil defense and emergency situations, and our local EMERCOM guys often roped me into searches. I'll write a few strange cases here.

A 55-year-old man went missing. Quite wealthy. He quarreled with his wife, went out to walk the dog, and didn't come back. The dog, by the way, came home on its own, but a couple of days later. At the same time the cops were looking for him, since initially there was a version involving crime. They found this man purely by accident. Some lads ran into our search group. They said that this man, like on the flyer with his photo, was sitting on a chair in an abandoned house in a private sector. Well, they were sort of rummaging through abandoned houses and saw that man in one of them. When we came to the indicated house, we indeed found that man there. He was already dead. The body was just sitting on a chair. But the strangeness wasn't in that. The whole room was covered with strange and incomprehensible symbols. It probably wasn't even any language. Mostly there were all sorts of little dashes and circles, and there were a lot of intersecting lines. The deceased himself was sitting opposite a drawn corridor receding into the distance. He drew all of it himself. It was drawn with charcoal, and his hands were all smeared with that charcoal. By the way, later the cops said that under his clothes he had also covered his body with similar symbols. The cause of death was heart failure. He died two days before we found him. According to his wife, the deceased had never been interested in anything occult like that, moreover he considered all mysticism nonsense. Mentally he seemed healthy too.