Lincolns Secret Killer

Was Abraham Lincoln dying of cancer when he was killed? National Geographic is on the front lines as scientists attempt to solve a genetic mystery-using a piece of fabric stained with the president's blood to run DNA analysis. The final year of Lincoln's life seemed to age him a decade, and he had lost an alarming amount of weight. Even today, his strange body shape, unusual height and long limbs have led to speculation that he harbored some hidden medical problem.

• documentary
• nonfiction