From Abraham Lincoln's assassination to 9/11 and beyond, the guilt or innocence of many of the United States' most famous criminals remains in doubt. Looked at in the context of their era, Did They Really Do It? investigates each case anew. The book begins with Dr. Samuel Mudd. He was convicted as part of the group of Confederates who conspired to murder President Lincoln in 1865. It was Mudd who set John Wilkes Booth's ankle which Booth broke when he leaped to the stage at Ford’s Theater after mortally wounding Lincoln. Claiming he never knew Booth, Mudd was sentenced to prison. While serving time, a Yellow Fever epidemic broke out, killing the prison doctor. Taking over, Mudd became a hero and President Johnson pardoned him in 1869. To his dying day, Mudd claimed innocence in the assassination plot. The last chapter focuses on Zacaharius Moussai, the alleged 20th hijacker in the "9/11" terrorist conspiracy who claims innocence. On the basis of a new investigation, this book proposes a dispassionate conclusion that Moussai is innocent. Other well known cases like Lizzie Borden, the alleged double ax murderess, and Bruno Richard Hauptmann, executed for killing the Lindbergh baby, are explored.