Gary was sentenced to death in 1986 for the rapes and murders of Florence Scheible, Martha Thurmond and Kathleen Woodruff.
The killings stopped in 1978 but Gary was not arrested until 1984 when he was linked to a gun stolen in one of the victim's homes.
Attorneys for Gary had submitted a clemency request saying the convicted murderer is innocent and evidence proves he did not commit the crimes, but a Georgia Patrol board announced Wednesday that the request was denied.
The board's order leaves the execution scheduled for 7 p.m. Thursday at the Georgia Diagnostic and Classification Prison in Jackson.
His lawyers also claim that a police report states that the woman who identified Gary as her attacker had told detectives that she was asleep at the time of the attack and she wouldn't be able to identify the man because it was dark in her bedroom.
Gary's execution was scheduled once before, in 2009.
Wednesday's meeting was held to receive information for or against clemency.
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The couple had wanted to see if the bullet would go through the book, but were standing just one foot from each other. He said she could serve her time in 10-day increments over the next three years as set out in the plea agreement.
In last-minute appeals, attorneys for Gary cited the same evidence used a year ago while trying to get Gary a new trial or sentence in Muscogee Superior Court, where a judge rejected those motions in September, according to the newspaper.
The arguments in the clemency petition have previously been raised in court filings, and lawyers for the state have consistently disputed their validity. The woman survived the attack and testified that Gary was her attacker.
Since the state says the same person carried out all the attacks, excluding him from even one "would prove, under the prosecution's own theory, that Mr. Gary was innocent of all nine attacks", his lawyers wrote. DNA analysis would have provided further evidence, they wrote, but it couldn't be done because the samples were discovered to have been contaminated at the Georgia Bureau of Investigation crime lab. Prints from the crime scenes also connected him to the murders.
Authorities have said Gary confessed to participating in the burglaries but said another man committed the rapes and killings.
According to CBS, the evidence included in the clemency application has all been presented in court filings and were disputed by the state due to their validity.
Martin says the jury member, Jack Pickel, says he would never have voted for the death penalty for Gary had he known one of the state's key witnesses couldn't identify Gary as her attacker.