The zombies on wheels
I was employed at a residential mental health hospital early in my career as a psychiatric nurse. One of our residents was an elective mute, meaning there was no medical explanation for his inability to speak or his refusal to speak. Speaking earlier in life, he actually appeared very normal, save from being nearly seven feet tall. Having grown up in the Deep South, he enlisted in the military at the age of 19, but one evening he disappeared. After being listed as AWOL, he was ultimately reported missing and deceased.
In my area of the Midwest, ten years later, a man standing seven feet tall entered the emergency room of a VA hospital and introduced himself to the receptionist, saying, "My name is Marion Duchene (not the real name), and I've been dead for ten years." He never said anything more after that.
The identical clothes that had been reported on him the night he vanished were on him, and he was covered in dust. He lacked any identification on him and his social security number was unused. Still, I suppose they were able to identify him by his fingerprints. When the family was informed, they stated that they had already come to terms with the loss of their loved one and that the person claiming to be him could not be him. They insisted on never being contacted again.
Marion paced nonstop, moving his mouth in a way that suggested he was speaking or murmuring, but nothing came out. He had a startling habit of cocking his head back and gaping widely as though he was laughing heartily, yet there was no sound, not even a breath. He seemed to listen to me if I spoke to him, occasionally cocking his head back in the manner he does when he laughs. We tried a number of drugs, but none had any effect on him—positive or negative. Marion would merely smile and would get up and start pacing again unless told to stay seated, thus occupational therapy was ineffective.
The final thing that I saw Marion doing on my last day of that work was him pacing around the parking lot and cocking his head back to "laugh." I later questioned whether I had been working with a ghost the entire time. Even after all these years, I'm still not sure.
For me, it's truly a mystery and a haunted circumstance.