Troy Davis enters Chatham County Superior Court Aug. 22, 1991, in Savannah, Ga. (AP)
JACKSON, Ga. -- Convicted murderer Troy Davis was executed by lethal injection and pronounced dead at 11:08 p.m. ET Wednesday, said Kristen Stancil, a spokeswoman at the prison where Davis died. He was 42.
COMPLETE COVERAGE: The Troy Davis Case
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PHOTO GALLERY: Troy Davis' execution day
Davis was convicted in 1991 for the 1989 murder of off-duty Savannah Police Officer Mark MacPhail, who was fatally shot while helping a homeless man who was being attacked.
Members of MacPhail's family sat in the front row during Davis' execution. With his last words, Davis told the family he was sorry for their loss, but "I'm not the one who personally killed your son, your father, your brother. I am innocent." He said he did not have a gun and urged the family to "look deeper into this case so that you really can finally see the truth."
A reporter who witnessed the execution said Davis went on to say, "I ask my family and friends to continue to fight this fight. For those about to take my life, God have mercy on your souls. And may God bless your souls."
Following the execution, Anneliese MacPhail, the 77-year-old mother of the slain officer, said, "It's over. It sounds terrible, but I can finally close this book."
Her family maintained their belief in Davis' guilt and she said they were tired of dredging up old memories with each review of the case.
"I have been through all the courts, and that is awful hard because they always talk about what happened to Mark from the day he got shot, and you see all the things and the bloody uniform," Anneliese MacPhail said. "That just tears my heart up."
The final effort to spare Davis' life was turned down by the U.S. Supreme Court late Wednesday.
"The application for stay of execution of sentence of death presented to Justice (Clarence) Thomas and by him referred to the Court is denied," read the order released to the news media at 10:18 p.m. ET.
The High Court's action was the latest dramatic turn in a case that had generated global attention. The NAACP, Amnesty International USA, other grassroots groups, elected officials and celebrities had all rallied around Davis, pointing out that several witnesses in Davis' initial trial had signed affidavits recanting their testimonies and saying police had coerced them into implicating Davis.
Kim Kardashian, Joan Baez and Heavy D were among the celebrities condemning the execution. Some urged their millions of Twitter followers to contact a judge in Georgia they believed could still grant a stay.
NAACP chief Benjamin Jealous had been lobbying state and federal officials to study what he felt was reasonable doubt in the case. He appeared on CNN Wednesday afternoon with a woman who claimed to have met a man at a party who admitted to killing MacPhail. Quiana Glover said she had given that information to the pardons board.
"In death, Troy Davis will live on as a reminder of a broken justice system that kills an innocent man while a murderer walks free," Jealous tweeted late Wednesday. "The pillar of strength that Troy has been is a testament to his faith and understanding that this movement will continue with more force."
More than 200 demonstrators gathered outside the Georgia Diagnostic and Classification Prison before the execution. Among them were activist Al Sharpton, rapper Big Boi of the Atlanta group OutKast, and Amnesty International USA executive director Larry Cox. Howard University students demonstrated at the White House.
Davis had been scheduled to die by lethal injection at 7 p.m. ET after a last meal of institution cheeseburgers, potatoes, baked beans, cole slaw, cookies and grape beverage.
About 10 minutes before the scheduled execution, White House press secretary Jay Carney issued a statement saying, "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." Supporters had hoped the president would ask the Justice Department to intervene.
Earlier Wednesday, the Georgia State Board of Pardons and Paroles turned down a request to reconsider its denial of clemency for Davis, and the state Department of Corrections rejected Davis' request to submit to a lie detector test.
Al Sharpton said he planned to meet with elected officials in Washington on Friday in hopes of creating legislation barring states from executing anyone in a case that lacks physical evidence. Sharpton said the proposed measure could be called "The Troy Davis Rule."
"There is no DNA, no gun, no physical evidence," Sharpton said. "That is unheard-of in a civilized society. This is much bigger than Troy Davis. It's about people having the right to seek redress. We are here because this is an outrage, and we want to show it's an outrage."
Former Presdident Jimmy Carter said Davis' execution shows the nation's death penalty system is "unjust and outdated." He told the Associated Press he hopes "this tragedy will spur us as a nation toward the total rejection of capital punishment."
Following Davis' execution, Officer MacPhail's widow Joan MacPhail-Harris said, "There's nothing to rejoice." She said she will grieve for Davis' family because now they will understand her family's pain and hurt.
(The Associated Press contributed to this report.)