ATLANTA (AP) — Georgia’s execution of Troy Davis for the murder of an off-duty police officer has done little to resolve the debate over his guilt that captured the attention of thousands worldwide, including a former president and the pope.

Davis remained defiant even after he was strapped to a gurney Wednesday night in the state’s death chamber, declaring his innocence and urging the victim’s family to continue searching for the truth.

“I ask my family and friends to continue to fight this fight,” Davis said in his final statement.

Demonstrators wept during a candlelight vigil outside the prison. High-profile figures, including former President Jimmy Carter, said there was too much doubt surrounding Davis’ conviction and that his execution called the entire death penalty system into question.

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Carter said he hoped the case would lead Americans to reject capital punishment.

“If one of our fellow citizens can be executed with so much doubt surrounding his guilt, then the death penalty system in our country is unjust and outdated,” Carter said.

Other supporters included, Pope Benedict XVI, a former FBI director, the National Association for the Advancement of Colored People, several conservative figures and many celebrities.

Hundreds of thousands of people signed petitions on Davis’ behalf. Supporters staged vigils in the U.S. and Europe, declaring “I am Troy Davis” on signs, T-shirts and the Internet. Some tried increasingly frenzied measures, urging prison workers to stay home and even posting a judge’s phone number online. President Barack Obama, who could not have granted Davis clemency because it was a state case, deflected calls to get involved.

Relatives of the slain officer, Mark MacPhail, said the execution marked an end to years of legal turmoil and rejected his claims of innocence.

“He’s been telling himself that for 22 years. You know how it is, he can talk himself into anything,” said the officer’s mother, Anneliese MacPhail.

Davis had been convicted of MacPhail’s 1989 killing. Prosecutors said Davis was pistol-whipping a homeless man after asking him for a beer when MacPhail, who was working as a security guard at the time, rushed over to help. Authorities said Davis had a smirk on his face when he shot the officer in a Burger King parking lot in Savannah.

Witnesses placed Davis at the crime scene and identified him as the shooter, but seven of nine key witnesses have recanted all or parts of their accounts. 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, though state and federal judges have repeatedly ruled against him.

No gun was ever found, but prosecutors say shell casings were linked to an earlier shooting for which Davis was convicted.

Davis’ execution had been halted three times since 2007. The U.S. Supreme Court even gave Davis an unusual opportunity to “clearly establish” his innocence in a lower court last year. But a lower court judge ruled that defense attorneys didn’t meet that standard — a higher bar than is set for prosecutors in proving guilt.

While the top U.S. court didn’t hear the case, they did set a tough standard for Davis to exonerate himself, ruling that his attorneys must “clearly establish” Davis’ innocence — a higher bar to meet than prosecutors having to prove guilt. After the hearing, a lower court judge ruled in prosecutors’ favor, and the justices didn’t take up the case.

On Wednesday night, his execution was again delayed as officials awaited word on whether the nation’s high court would take up Davis’ case. The justices ultimately declined without explaining the decision, clearing the way for Davis to be put to death shortly after 11 p.m. local time.

Dozens of protesters outside the White House called on the president to step in, and about 12 were arrested for disobeying police orders. Outside the U.S. Supreme Court and the Jackson prison where Davis was put to death, demonstrators chanted, “They say death row; we say hell no!” As many as 700 were outside the prison, though the crowd thinned as the night wore on and the outcome became clear.

For now, though, the nation’s executions will carry on: Mere hours after Davis’ execution, a judge signed a death warrant for another condemned inmate. And an Alabama inmate was set to be executed Thursday evening.

Davis remained upbeat and prayerful in his final hours, turning down an offer for a special last meal as he met with friends, family and supporters.

“Troy Davis has impacted the world,” his sister Martina Correia said before the execution. “They say, ‘I am Troy Davis,’ in languages he can’t speak.”

Officer MacPhail’s widow, Joan MacPhail-Harris, said 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 in a telephone interview from Jackson. “My prayers go out to them. I have been praying for them all these years. And I pray there will be some peace along the way for them.”

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Associated Press reporters Russ Bynum, Kate Brumback and Marina Hutchinson in Georgia; Eric Tucker and Erica Werner in Washington and Sohrab Monemi in Paris contributed to this report.

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Copyright 2011 The Associated Press.