Amnesty International writes:

"Troy Davis came within 24 hours of execution in July, 2007 before receiving a temporary stay of execution. But the Georgia Supreme Court denied Mr. Davis’ motion for a new trial and now he faces execution on September 23. Troy Davis was sentenced to death for the murder of Police Officer Mark MacPhail in Georgia. The case against him consisted entirely of witness testimony which contained inconsistencies even during the trial. Since then, all but two of the state's nine non-police witnesses from the trial have recanted or contradicted their testimony. Many of these witnesses have stated in sworn affidavits that they were pressured or coerced by police into testifying or signing statements against Troy Davis."

You can send a letter to the George Board of Prisons and Parole at
http://www.amnestyusa.org/death-penalty/troy-davis-finality-over-fairness/page.do?id=1011343