For generations, visitors and employees at the White House have claimed to have seen Abraham Lincoln's ghost. There is even a Wikipedia page dedicated to Honest Abe's apparition.
Now, one paranormal researcher believes he has photographic proof of Lincoln's spirit in the White House.
Joshua P. Warren says a 1950 photo taken in the White House basement shows a strange ghost-like figure that he believes is America's 16th president.
"The place where the photo was taken is directly below the Lincoln Bedroom, and since Lincoln is the ghost most reported being seen in the White House, I think it could be Lincoln," he told The Huffington Post.
The photo Warren is referring to was taken by longtime White House photographer Abbie Rowe. It shows a man in a bulldozer in the foreground, and a group of men in the background on the left. In the rear center of the photo is the figure of a man who seems to be transparent.
Warren says the bizarre ghost-like image in the photo wasn't noticed until 2008 when the photo appeared in "Truman," David McCullough's 1992 Pulitzer Prize-winning biography.
The man who found the photo, Bob Martin, sent a letter to the author asking about the image, but received no response.
Warren may believe that transparent man is the ghost of Lincoln, but other people are more skeptical.
In a mini-documentary Warren made about the photo, he interviews various photographers, all of whom suspect the so-called ghost image was most likely caused by a long exposure or double exposure.
"There is a man down in front of the photo walking down a mound of dirt (see following image)," Warren said. "You can see by his position that there was only one or two seconds between the time when the shutter was open and when it closed."
Bryan Bonner of the Rocky Mountain Paranormal Research Society thinks there's more than a ghost of a chance the photographers are right and Warren is wrong.
"This photograph is a classic example of 1950’s architectural photography, which means that they did not really care about the people in the image as they did about documenting the construction," Bonner told HuffPost by email. "With my over 30 years of photographic experience, I have no doubt that this image is just a blurred person."
Warren suspects the ghostly figure is slightly taller than an average person, based on how the heads of the men on the left all touch the dark, horizontal streak in the background.
He explains it on his website:
If we assume the three men are of average height, this means the figure is likely taller than average (though we are uncertain about the grade of the ground on this construction site). Lincoln was approximately 6 feet 4 inches so this is also consistent with the possibility we are seeing Lincoln's apparition."
Ben Radford, deputy editor of Skeptical Inquirer magazine, says "ghostly" images like the one Warren is getting excited about are abundant in long exposure photography, including many Civil War photographs.
"There is nothing unusual about the image. In fact I’d be surprised if a close review of Rowe’s other photos taken around the same time with the same equipment didn’t reveal similar 'ghosts,'" Radford told HuffPost by email.
"Warren is basically arguing that if he personally couldn’t replicate or explain the photo, then nobody can, and therefore, it’s a ghost and since it’s the White House, it’s the ghost of Abraham Lincoln," Radford said. "It’s funny how it’s never thought to be the ghost of a lesser known president, like Fillmore or Polk."
Warren believes he could better prove his case if he had access to the original negative or permission to do a ghost-hunting investigation at the White House.
He's been denied both requests, which perturbs him.
"There seems to be a conspiratorial air," he said. "I was born in the U.S. and have no criminal record. I received a security clearance to visit the White House in 2011 and I have a valid U.S. passport. There is no reason why I shouldn't have access to this photo."
Warren says the "Lincoln Ghost" pic is one of many taken during the Truman administration that were declared classified in 1978 by Jimmy Carter.
"Truman was president when the Roswell crash happened, as well as the formation of the CIA and NSA, so it's possible there are other photos in that file that might surprise us," Warren said.
However, Radford is more surprised that anyone would consider what Warren calls “the world’s most credible and amazing ghost photo” to be serious evidence of the supernatural.
"If this really is the best photographic evidence for ghosts -- if a published expert on ghosts can’t tell the difference between an ordinary long exposure and a ghost -- then the quality of ghost evidence is in far worse shape than I imagined," Radford said.