Thomas Austin Jones did more to help John Wilkes Booth and Davy Herold escape to Virginia than any other person. He was arrested, but he was never tried.
Jones hid the men in a pine thicket for days and supplied food, a compass and a boat for them to cross over to Virginia, but, because Davy Herold never fingered him as the man who helped them, authorities were unable to build a case against him.
In 1893, Jones outed himself, when he published a book detailing his adventures as a Confederate agent and his role in helping Booth and Herold. By then, the government did nothing to pursue the case.
Source: The Lincoln Assassination Encyclopedia by Edward Steers Jr.