 Eight others implicated in Lincoln's assassination were tried by a military tribunal in Washington, D.C., and found guilty on June 30, 1865.Mary Surratt, Lewis Powell, David Herold, and George Atzerodt were hanged in the Old Arsenal Penitentiary on July 7, 1865.Samuel Mudd, Samuel Arnold, and Michael O'Laughlen were sentenced to life imprisonment at Fort Jefferson in Florida's isolated Dry Tortugas.