The seven-week trial included the testimony of 366 witnesses. All of the defendants were found guilty on June 30. Mary Surratt, Lewis Powell, David Herold, and George Atzerodt were sentenced to death by hanging; Samuel Mudd, Samuel Arnold, and Michael O'Laughlen were sentenced to life in prison. Edmund Spangler was sentenced to six years. After sentencing Mary Surratt to hang, five members of the tribunal signed a letter recommending clemency, but Johnson did not stop the execution; he later claimed he never saw the letter.