The figure peers down silently from an upper floor of the ruins of a Scottish castle, wearing what looks like an outfit from the Middle Ages. Could this be a long-dead Scottish earl, or just a random, modern-day visitor?
The eerie image is captured in a photograph taken by tourist Christopher Aitchison in May 2008 at Tantallon Castle, which sits on a rocky outcrop along the Scottish coast, east of Edinburgh. The "person" appears to be wearing an old-style greenish ruff around the neck.
Aitchison insists he did not tamper with the image and cannot explain it.
"I was not aware of anyone, or anything, being present in my picture, only noticing the anomaly when I got home," Aitchison said. "Staff have verified that there were no sinister dummies in period costume or historical reenactments going on that day at the castle. I did not notice any nice old ladies wearing ruffs walking around the stairs!"
The picture was made public Friday by Richard Wiseman, a professor of psychology at the University of Hertfordshire who also studies the paranormal. Wiseman said he was looking for "photographic evidence for ghosts" ahead of a session on the subject at the Edinburgh International Science Festival next week.
Tantallon Castle was built in the 1350s by a nobleman and soon became the stronghold of the Douglas dynasty. For 300 years, the Douglas earls of Angus held sway at the castle as one of the most powerful families in Scotland, according to Historic Scotland, which looks after historic sites for the Scottish government.
The castle also was the scene of violence, enduring three great sieges: in 1491, 1528 and 1651. The last, by Oliver Cromwell's army, resulted in such destruction that the fortress was abandoned.
It remains the "last truly great castle" built in Scotland, with enormously thick and high stone walls enclosing large courtyards, and high stone towers.
That stonework could explain the mysterious figure in the photograph, having caused unusual shadows. It is also possible that a member of the public was standing there when the picture was taken, Wiseman said -- in which case, he hopes they will come forward.
"I think it's probably a person who's been caught in slightly odd dress," Wiseman told CNN. "We know the day it was taken ... so somebody might come forward to say, 'That was me.'"