Troy Davis was convicted in Georgia of the 1989 fatal shooting of an off-duty police officer, who came to the assistance of a homeless man who was being beaten by a group of assailants that included Davis. But his guilt in the murder was challenged by the NAACP and the Innocence Project, an organization that has exonerated 18 death row inmates between 1992 and 2012 .
Seven of the nine trial witnesses against Davis later recanted their testimony, adding to the outcry against his execution. (Some said one of the two remaining witnesses was the real killer.) About 630,000 people signed petitions asking that his execution be stopped.
In 2007, a state parole board temporarily blocked his execution with just hours to spare, and the following year, the U.S. Supreme Court intervened just 90 minutes before he was to die, though it eventually declined to hear his case.
On Sept. 20, 2011, Davis' execution was put on hold one more time, as the Supreme Court reviewed a last-ditch petition from his lawyers. But unfortunately for him, the justices decided not to intervene. Just before 11 p.m., four hours after the scheduled time, Davis was walked into the death chamber. He continued to maintain his innocence, even looking the family of the murdered officer in the eye and telling them, "I did not personally kill your son, father, brother. All I can ask is that you delve deeper into this case so you really can finally see the truth." Eight minutes later, he was pronounced dead [source: Severson].