It's on an envelope that was with papers Bruce Steiner bought in 2006 in South Amherst, 30 miles southwest of Cleveland. The writing says: "Let this man enter with this note. April 14, 1865," and it's signed "A. Lincoln." The date is the day the president was shot.
A handwriting analysis has been done by John Lupton, who's involved in a project to preserve Lincoln's paper at the Lincoln library in Springfield, Ill. Lupton says he's "pretty sure" the signature is genuine, because it has Lincoln's distinct characteristics.
A Lincoln memorabilia dealer says it could be worth up to $25,000. Steiner says he paid about $20 for the papers.
Steiner doesn't plan to sell.