Lincolns Secret KillerWas 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