Death row inmate Troy Davis has been in familiar situations before, but this time it looks like his chances of clinging on to life are slimmer than all times before.

After the Georgia Board of Pardons and Paroles denied his clemency plea and said his execution would take place as per schedule at 7 p.m. on Wednesday, observers are giving slim chances for the judicial system to give him another chance.

Davis was convicted in 1991 on the basis witness accounts that said he was seen shooting police officer Mark MacPhail in Savannah in 1989. He was 19 years old when he was arrested for the murder. The 42-year-old has long professed he's innocent of killing the off-duty police officer.

His case gained international attention ever since he was sentenced to death by lethal injection. Those who support him say no physical evidence was presented against him during trial. Multiple witnesses have recanted or changed their stories in the years after the murder, it has been pointed out.

Even high profile personalities like ex-president Jimmy Carter supported his attempts for being granted clemency.

Davis was scheduled to die at Georgia Diagnostic and Classification Prison near Jackson, Ga. by lethal injection on Wednesday night after the parole board, which is the only authority in the state with the power to commute a death sentence, denied last-minute plea for clemency.

The board has considered the totality of the information presented in this case, and thoroughly deliberated on it ... After which the decision was to deny clemency, board spokesman Steve Hayes said in a terse statement.

Legal circles say the parole board decision is not surprising. However, according to Davis's defense team, his death sentence was wrong as the conviction was allegedly based on flawed testimony by witnesses. They also point out that some testimonies were largely recanted later.

However, the family of the killed police officer says justice to him will be served when Davis is executed. Justice was finally served for my father ... The truth was finally heard, said Mark MacPhail Jr, the dead officer's son, according to CBS News.

There are a number of people who say the alleged uncertainty of his guilt will make this execution look grossly unfair and illogical.

In the end, I am not concerned so much with whether or not Davis is guilty or innocent. I am concerned with the uncertainty of his guilt, wrote E.D. Kain in a article.

... But if we have even a glimmer of doubt about his guilt, there will be no justice in his death. If we have even a hint of uncertainty over whether this man did the deeds he was accused of, but which most of his accusers have since recanted, we should stay his execution, he said.

However, according to legal experts, no realistic avenue is open in front of him. Davis had been agonizingly close to execution a couple of times before, but each time he was granted more time.

At first, his execution was scheduled to take place in July 2007. But Davis was given a stay of execution by the pardons board less than 24 hours before the scheduled time. A year later, he was again agonizingly close to death, but got a reprieve from the U.S. Supreme Court, just two hours before he was to be given the lethal injection. A few months later, the federal appeals court stepped in to halt the execution process yet again.

This time it looks different. State officials said they were pretty certain that the execution would be carried out, CBS reported. Georgia's Governor does not have the power to grant clemency to a death row inmate. The report says his supporters called upon the Chatham County District Attorney to block the execution, but the prosecutor said he was powerless to withdraw the execution order.

Protests have been held throughout Georgia and elsewhere, including New York, Washington, Los Angeles and around the globe. After the parole decision, the Rev. Marvin Morgan went to the board offices in downtown Atlanta and chained himself to a flagpole, protesting Davis's execution, before police cut him free and arrested him.

If the state of Georgia can intentionally kill a person in a case surrounded with this much doubt, then we're all subject to the same fate, the Los Angeles Times reported, quoting Morgan.

Jonathan Perri, a senior organizer on criminal justice for, which helped organize a campaign to save Davis, says the case is unique for the broad support it has generated.