FILE - This May 14, 2012 file photo shows tourists outside Abraham Lincoln's home in Springfield, Ill. It's been more than 25 years since workers renovating Abraham Lincoln's home found a letter fragment in a mouse's nest inside a wall. But researchers with The Papers of Abraham Lincoln think they've finally identified the author of the mystery letter as newspaper editor Andrew Johnston. The March 10, 1846, letter sent from Quincy, Ill., was Johnston's reply to a poem the future president had shared with him. (AP Photo/Seth Perlman, File)