WASHINGTON (CNN) -- The U.S. Supreme Court delayed a decision on whether to accept an appeal from a Georgia death row inmate who has gained international support for his claims of innocence in the the murder of a Savannah police officer two decades ago.
Troy Davis' case has earned the support of leaders including the pope and former President Jimmy Carter.
The justices were scheduled to announce Monday whether they would take the case of Troy Davis, but no order was released. The court is expected to take up the matter again in September.
Last fall, the Supreme Court granted Davis a stay of execution two hours before he was to be put to death. A month later, the justices reversed course and allowed the capital punishment to proceed, but a federal appeals court issued another stay.
The high court's latest delay means Davis will continue to sit on death row. 
Watch a report on Davis' long fight »
His supporters Monday delivered about 60,000 signatures in petitions to Chatham County, Georgia, District Attorney Larry Chisolm, calling for a new trial.
"This delay is an indication that the Supreme Court is concerned by the gravity of Troy Davis' innocence claims," said Laura Moye, director of Amnesty International USA's Death Penalty Abolition Campaign. "We will continue to call on all authorities, including the Supreme Court, to finally hear the evidence that has motivated hundreds of thousands of people worldwide to raise their voices and demand justice."
Davis has always maintained his innocence in the 1989 killing of Officer Mark MacPhail. Witnesses claimed Davis, then 19, and two others were harassing a homeless man in a Burger King restaurant parking lot when the off-duty officer arrived to help the man. Witnesses testified at trial that Davis then shot MacPhail twice and fled.
But since his 1991 conviction, seven of the nine witnesses against him have recanted their testimony. No physical evidence was presented linking Davis to the killing of the police officer.
The Georgia Pardons and Parole Board last year held closed-door hearings and reinterviewed Davis and the witnesses. The panel decided against clemency.
MacPhail's mother, Annaliese, told CNN at the time, "This is what we were hoping for, and I hope pretty soon that we will have some peace and start our life, especially my grandchildren -- my grandson and granddaughter. It has overshadowed their lives."
After the justices in October refused to grant a stay of execution, Davis' sister, Martina Correia, told CNN she was "disgusted" by the decision.
"It doesn't make any sense," she said. "We are praying for a miracle or some kind of intervention. We will regroup and fight. We will never stop fighting. We just can't be discouraged. The fight is not over 'til it's over."
Ten days after the high court refused last October to intervene, a federal appeals court in Georgia granted a temporary stay of execution. Since then, further appeals by Davis' legal team have dragged on for eight months.
Prominent figures ranging from the pope to the musical group Indigo Girls have asked Georgia to grant Davis a new trial. Other supporters include celebrities Susan Sarandon and Harry Belafonte; world leaders such as former President Jimmy Carter and former Archbishop Desmond Tutu of Cape Town, South Africa; and former and current U.S. lawmakers Bob Barr, Carol Moseley Braun and John Lewis.
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