Atlanta ( CNN ) -- Georgia 's parole board convened Monday morning to hear a last-minute appeal by Troy Davis , who is set to die by lethal injection for the murder 21 years ago of a Savannah police officer . A jury convicted Davis of murder in 1991 , paving the way for his execution , which has been delayed three times and is now scheduled for 7 p.m. Wednesday at a state prison in Jackson , Georgia . The Georgia Board of Pardons and Paroles noted in a press release Sunday it is `` the sole authority in Georgia for granting clemency to inmates . '' Options for the board include commuting a death sentence without parole , giving a convict a life sentence or denying clemency -- which , in this case , would pave the way for Davis ' execution . In addition to Davis and his supporters making their appeal , the victim 's mother , Anneliese MacPhail , told CNN this weekend that she , too , plans to attend . Many of Davis ' supporters , who believe he was wrongly convicted and have staged rallies in recent days calling for his release , will not be allowed in . But in a statement Sunday , officials with Amnesty International , the NAACP and Georgians for Alternatives to the Death Penalty issued a fresh appeal for people to join them Monday for prayers , musical performances and speeches outside the building where the board will meet . According to these groups , there have been about 300 rallies , vigils and events worldwide since last week . In addition , they say that more than 1 million people have signed a petition in support of Davis ' bid to be exonerated . Since his 1991 conviction , seven of the nine witnesses against him have recanted or contradicted their testimony . There also have been questions about the physical evidence -- and , according to some , the lack thereof -- linking Davis to the killing . But the mother of Mark MacPhail , the police officer killed that night , said that those rallying do n't understand all the facts of the case . She is convinced that Davis shot her son , and that the jury 's decision to convict him was fair . `` I 'm not out after blood , I 'm after justice , '' said Anneliese MacPhail , adding she does n't plan to attend the execution . `` I want my son to rest in peace . '' In a 2008 statement , then-Chatham County District Attorney Spencer Lawton described how Davis was at a pool party in Savannah when he shot another man , Michael Cooper , in the face . Davis was then driven to a nearby convenience store , where he pistol-whipped a homeless man , Larry Young , who 'd just bought a beer . Soon thereafter , prosecutors said MacPhail -- who was working in uniform , off-duty , at a nearby bus station and restaurant -- arrived . It was then , the jury determined , that Davis shot the officer three times , including once in the face as he stood over him . Davis ' lawyers , in a petition to a U.S. District Court , insisted that there is `` no physical evidence linking '' Davis to MacPhail 's murder . They point , too , to `` the unremarkable conclusion '' of a ballistics expert who testified that he could not find definitively that the bullets that wounded Cooper and killed MacPhail were the same . Georgia 's attorney general , in an online statement , claims that the expert said the bullets came from the same gun type and noted that casings at the pool party shooting matched -- thus came from the same firearm as -- those found at MacPhail 's murder scene . Two decades ago , a jury convicted Davis on two counts of aggravated assault and one each of possessing a firearm during a crime , obstructing a law enforcement officer and murder . The latter charge led , soon thereafter , to his death sentence . While reviewing Davis ' claims of innocence last year , the U.S. District Court for the Southern District of Georgia found that Davis `` vastly overstates the value of his evidence of innocence . '' `` Some of the evidence is not credible and would be disregarded by a reasonable juror , '' Judge William T. Moore wrote in a 172-page opinion . `` Other evidence that Mr. Davis brought forward is too general to provide anything more than smoke and mirrors , '' the court found . The Rev . Raphael Gamaliel Warnock , who is set to testify before the parole board Monday , said that he `` can only begin to imagine the pain ( the MacPhail family ) must be feeling . '' MacPhail `` was protecting the community , and there is no pain greater than when a parent loses a child , '' Warnock said . Still , he believes `` there is too much doubt in this case for an execution . '' `` I have met with ( Davis ) on death row , '' Warnock said . `` I believe he is innocent . '' The odds do not appear to be in Davis ' favor . The parole board denied him clemency once before . And the board has never changed its mind -- on any case -- in the past 33 years .
Troy Davis is set to die by lethal injection on Wednesday . The parole board will hear his argument he 's not guilty of Mark MacPhail 's murder . The Savannah police officer died after being shot three times in 1989 . Advocacy groups claim over one million have signed a petition in support of Davis .