Who were the 4 men killed for the Lincoln assassination conspiracy?

Who were the 4 people killed for the Lincoln assassination conspiracy? I know 3 of them were: John Wilkes Booth, Lewis Powell, and George Atzerodt. But who was the 4th? Thanks.|||The fourth was Mary Surratt. She was the first women ever to be sentenced to death in the U.S. legal system. She was the keeper of the house where the conspirators met. She was convicted of being the mastermind of the entire plot, including the attempted murder of William Seward.