JACKSON, Ga. — Troy Davis was put to death by lethal injection late Wednesday for the 1989 murder of an off-duty police officer, maintaining his innocence until the end after convincing thousands of it, but not the justice system.
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Davis was declared dead at 11:08 p.m. EDT, a prison official said.
His execution, which began at 10:53 p.m., came after a three-hour hold while the Supreme Court considered a late request for a stay. In the end the court refused to stop the execution, despite calls for clemency from former President Jimmy Carter, Pope Benedict XVI and others.
Davis' attorneys say seven of nine key witnesses against him recanted all or parts of their testimony, but state and federal judges repeatedly ruled against granting him a new trial.
Troy Anthony Davis
Media witnesses said that on his death bed, Davis told the family of the slain officer, Mark MacPhail, that he was very sorry for their loss but that he wasn't responsible for his death.
"It's not my fault; I did not have a gun," he said while strapped to a gurney, according to witness Rhonda Cook of the Atlanta Journal-Constitution. "I did not personally kill your son, father, brother," he said, Cook reported.Video: Troy Davis executed in Georgia (on this page)
He asked his family and supporters to "dig deeper" into the case after his death "so you can find the real truth."
"For those about to take my life," he told prison officials, "may God have mercy on your souls. May God bless your souls."
MacPhail's family attending the execution never turned their heads or wavered, said witness John Lewis of WSB radio. They included the officer's son, Mark MacPhail Jr., and brother, William MacPhail.
"They just stared at the glass, watching as the execution happened," he said.
MacPhail's widow, Joan MacPhail-Harris, said in a telephone interview from Jackson there was "nothing to rejoice," but that it was "a time for healing for all families."
"I will grieve for the Davis family because now they're going to understand our pain and our hurt," she said. "My prayers go out to them. I have been praying to them all these years. And I pray there will be some peace along the way for them."
"I'm kind of numb. I can't believe that it's really happened," MacPhail's mother, Anneliese MacPhail, said in a telephone interview from her home in Columbus, Ga. "All the feelings of relief and peace I've been waiting for all these years, they will come later. I certainly do want some peace."
Of Davis' claims of innocence, she said, "He's been telling himself that for 22 years. You know how it is, he can talk himself into anything."
Members of Davis' family who witnessed the execution left without talking to reporters.
A crowd of 700 Davis supporters who had gathered outside the prison in the afternoon dwindled to about 50 as the minutes, then hours, passed.
When word of the delay came, they cheered and sang "We Shall Overcome."
After the execution, the group started to clap and quietly sing while police maintained a large presence with riot gear including tear gas, tasers, and hand restraints, NBC News reported.
About 10 counterdemonstrators also were outside the prison, showing support for the death penalty and MacPhail's family.Video: Was an innocent man executed? (on this page)
The Supreme Court had received the request for a stay less than an hour before the 7 p.m. ET time set for the execution, then delivered a one-sentence rejection more than three hours after the time had passed.
State officials had waited for the response.
"We are in a delay, waiting for a decision from the U.S. Supreme Court," Peggy Chapman of the Georgia Department of Corrections told NBC News earlier.
The court had no deadline for a decision, and the state was under no obligation to wait, NBC News reported.
The U.S. Supreme Court's action came after Georgia's Supreme Court had rejected a last appeal by Davis’ lawyers. Earlier, a Butts County Superior Court judge also declined to stop the execution.
In their U.S. Supreme Court filing, Davis' attorneys said "substantial constitutional errors" were made when the lower courts denied his claims that "newly available evidence reveals that false, misleading and materially inaccurate information was presented at his capital trial in 1989, rendering the convictions and death sentence fundamentally unreliable," NBC News reported.
The lawyers said they've been struggling to get these claims heard in the lower courts "after having a grueling clemency process."
Davis and his supporters have maintained his innocence. Prosecutors have stood by the case.
Davis' supporters held vigils outside Georgia's death row and as far away as London and Paris. They declared "I am Troy Davis" on signs, T-shirts and the Internet. They also tried increasingly frenzied measures, urging prison workers to stay home and even posting a judge's phone number online, hoping people will press him to put a stop to the lethal injection.
"We're trying everything we can do, everything under the law," said Chester Dunham, a civil rights activist and talk show host protesting in Savannah, where MacPhail, 27, was killed.
Outside the Jackson prison earlier, demonstrators, including the Rev. Al Sharpton, gathered Wednesday afternoon for a prayer rally. As they shouted, "Free Troy Davis!" a man in a red SUV drove by and shouted, "Kill him! Kill him!"
Several dozen people gathered outside the White House to protest the execution. They held signs condemning it as a "lynching" and chanted "Too much doubt" and "What do we want? Justice!"
About 150 people gathered in support of Davis in Paris, many of them carrying signs emblazoned with his face. "Everyone who looks a little bit at the case knows that there is too much doubt to execute him," Nicolas Krameyer of Amnesty International said at the protest.
Davis' execution had been stopped three times since 2007, but on Wednesday the 42-year-old appeared to be out of legal options.
As his last hours ticked away, an upbeat and prayerful Davis turned down an offer for a special last meal as he met with friends, family and supporters. His attorney Stephen Marsh said Davis would have spent part of that time taking a polygraph test if pardons officials had taken his offer seriously.
"He doesn't want to spend three hours away from his family on what could be the last day of his life if it won't make any difference," Marsh said.
Davis' supporters also include a former FBI director, the NAACP, and several conservative figures. Amnesty International says nearly 1 million people have signed a petition on his behalf. The U.S. Supreme Court even gave him an unusual opportunity to prove his innocence in a lower court last year, though the high court itself did not hear the merits of the case.
He was convicted in 1991 of killing MacPhail, who was working as a security guard at the time. MacPhail rushed to the aid of a homeless man who prosecutors said Davis was bashing with a handgun after asking him for a beer. Prosecutors said Davis had a smirk on his face as he shot the officer to death in a Burger King parking lot.
No gun was ever found, but prosecutors say shell casings were linked to an earlier shooting for which Davis was convicted.
Witnesses placed Davis at the crime scene and identified him as the shooter, but several of them have recanted their accounts and some jurors have said they've changed their minds about his guilt. Others have claimed a man who was with Davis that night has told people he actually shot the officer.
Interactive: Troy Davis (on this page)
"Such incredibly flawed eyewitness testimony should never be the basis for an execution," Marsh said. "To execute someone under these circumstances would be unconscionable."
State and federal courts, however, have repeatedly upheld Davis' conviction. A federal judge dismissed the evidence advanced by Davis' lawyers as "largely smoke and mirrors."
The motion filed Wednesday by Davis' attorneys in Superior Court in Butts County disputed testimony from the expert who linked the shell casings to the earlier shooting involving Davis, and challenged testimony from two witnesses.
The NAACP, which helped lead the charge to stop the execution, had considered asking President Barack Obama to intervene.
Obama cannot grant Davis clemency for a state conviction.
Wednesday evening, White House Press Secretary Jay Carney said Obama would not get involved, NBC News reported.
"Dating back to his time in the Illinois State Senate, President Obama has worked to ensure accuracy and fairness in the criminal justice system — especially in capital punishment cases. However, it is not appropriate for the President of the United States to weigh in on specific cases like this one, which is a state prosecution."
In Savannah, Davis supporters presented petitions urging the state to spare Davis' life, saying they were signed by 240,000 people. They delivered the petitions to District Attorney Larry Chisolm, though he has said he was powerless to intervene.
Earlier Wednesday, six retired corrections officials, including Allen Ault, retired director of the Georgia Department of Corrections and former warden of the Georgia Diagnostic and Classification Prison, where he oversaw executions for the state, sent a letter to Georgia corrections officials and Gov. Nathan Deal asking them to urge the pardons board to reconsider its decision.
"We write to you today with the overwhelming concern that an innocent person could be executed in Georgia tonight," the letter said in part.
Davis' best chance may have come last year, in U.S. Supreme Court-ordered hearing. It was the first time in 50 years that justices had considered a request to grant a new trial for a death row inmate.
The high court set a tough standard for Davis to exonerate himself, ruling his attorneys must "clearly establish" Davis' innocence — a higher bar to meet than prosecutors having to prove guilt. After the hearing judge ruled in prosecutors' favor, the justices didn't take up the case.
NBC News, The Associated Press and msnbc.com staff contributed to this report.