The last desperate plea for clemency made on behalf of death row inmate Troy Davis was turned down on Tuesday, RadarOnline.com has learned, despite having received an outpouring of support from those who believe that he was wrongly accused of killing a police officer in 1989.

However, the convicted killer's supporters have still not given up hope as Davis' sister spearheads a campaign to save her brother.  Kim Davis launched an online petition 11 days ago at Change.org to appeal to the Georgia Board of Pardons and Paroles, and currently has 250,000 signatures supporting her sibling.

"She is not going to stop trying, she said she is going to keep pushing for this up until the very moment that it might happen," Jonathan Perri, Senior Organizer of the Criminal Justice division of Change.org told RadarOnline.com in an exclusive interview.

A man set to be executed on Wednesday is going for a last minute plea for clemency in order to avoid the death penalty and multiple witnesses have come forward to support his claim of innocence.  

Troy Anthony Davis was convicted of murdering an off-duty police officer in 1989, but his legal team is arguing that there is “abundant evidence” that another man committed the murder and say that they have “sworn statements from three jurors who sentenced Davis to death at his 1991 trial, but who now express doubt with their verdicts and are asking that Davis be spared the death penalty,” according to the Atlanta Journal and Constitution.

Davis’ attorneys have filed the clemency petition with the Georgia Board of Pardons and Paroles, noting that seven of the prosecution’s nine witness have either recanted or backed off their testimony.  More witnesses have come forward to say in sworn statements that Sylvester “Redd” Coles told them he was the one who pulled the trigger in the murder of Mark Allen MacPhail.  Coles was at the scene of the crime with Davis.