A major piece of unwritten history may be sitting in a Philadelphia museum and it's been there for decades. A pillowcase used by Abraham Lincoln the night he was shot may contain a sample of his DNA and a secret about the former President's health.

Inside this unassuming northeast Philadelphia Civil War museum, a strip of bloodstained pillowcase may answer a mystery that could change how we view one of our greatest presidents, Abraham Lincoln. Museum Vice President Andy Waskie says"This is a piece or strip of the pillowcase from the Peterson house in Washington upon which Lincoln's head rested after he's been shot at Ford's Theater across the street, soaked with his blood."

The Grand Army of the Republic Civil War museum says deep in those pillow fibers is Lincoln's DNA. And while other Civil War memorabilia at the museum, like John Wilkes Booth's handcuffs he intended to use on President Lincoln that night, might be more visually stimulating, it was the pillowcase that caught the eye of cardiologist and Lincoln historian, Dr. John Sotos. Sotos has long theorized that Lincoln had MEN2B, a fatal cancer gene....