Surratt, who owned a tavern in Surrattsville (now Clinton), Maryland, had to convert her row house in Washington D.C., into a boardinghouse as a result of financial difficulties. Located a few blocks from Ford's Theatre, where Lincoln was murdered, this house served as the place where a group of Confederate supporters, including John Wilkes Booth, conspired to assassinate the president. It was Surratt's association with Booth that ultimately led to her conviction, though debate continues as to the extent of her involvement and whether it really warranted so harsh a sentence. On the day of the assassination, Booth asked Surratt to deliver a package, which was later discovered to contain firearms, to her old tavern in Maryland. On her way home, Surratt ran into John Lloyd, a former Washington police officer who currently leased the tavern. When authorities first questioned Lloyd about their encounter, he did not mention anything significant and denied that Booth and David Herold had visited his tavern. Yet when questioned later, he claimed that Surratt had told him to have whiskey and weapons ready for Booth and Herold, who would be stopping by that night.
Louis Weichmann, one of the alleged conspirators who delivered the package with Surratt, was released after he testified against her. He later claimed that the government had forced him to testify, and that it plagued his conscience for the rest of his life. Furthermore, Lewis Powell, a conspirator who was hanged with Surratt, proclaimed her innocence to his executioner minutes before his death. Many expected President Andrew Johnson to pardon Surratt because the U.S. government had never hanged a woman. The execution was delayed until the afternoon, and soldiers were stationed on every block between the White House and Fort McNair, the execution site, to relay the expected pardon. But the order never came. Ever since her death, numerous sightings of Mary Surratt's ghost and other strange occurrences have been reported around Fort McNair. A hooded figure in black, bound at the hands and feet as Surratt had been at the time of her execution, has allegedly been seen moving about. Several children of soldiers have reported a "lady in black" who plays with them.