Watch Lincoln's Secret Killer: Revealed

Abraham Lincoln was the target in one of the most famous assassination cases in history, but was the President of the United States already suffering with a form of cancer that would have killed him soon after John Wilkes Booth assassinated him. A team of experts is employed in this documentary to look at photographs and written evidence that provides clues to the health of Lincoln. A small area of cloth reported to be stained with the blood of Lincoln is also used for DNA testing in a New Zealand lab to see what secrets it reveals.