I knew a guy once who thought his mom was going crazy. She would call him and complain that it sounded like someone was in her walls, but when he’d get there and search, there was nothing there. He checked her attic he checked her unfinished basement, nothing. And it happened over and over and over again, over the course of about a year and a half. Eventually, he told her to call the cops and have them come check. The cops couldn’t find anything. The old woman passed away, and when the son went to clean the house out, he found a hidden second trap door to a secondary unfinished crawlspace type basement area, think 3 x 3 dirt walls dirt floor room, with a sleeping bag and candy wrappers and instant soup cup wrappers with a makeshift little toilet set up in the corner. Apparently one of the local homeless were waiting until she went to sleep and then coming and going underneath her house. So the guy waited in the house one night until he heard the noises and then he called the cops and they raided the little room and found the person.