Troy Anthony Davis was executed at 11:08 p.m. EST Wednesday, after the U.S. Supreme Court refused to block Georgia authorities from executing him for the murder of an off-duty police officer in 1989.

In his final words, Davis maintained his innocence in the killing of Mark MacPhail. As he lay strapped to a gurney in the death chamber, Davis told MacPhail's relatives that he was not responsible for his slaying. "I did not have a gun," Davis said.

"All I can ask ... is that you look deeper into this case so that you really can finally see the truth," he said.

Davis asked his friends and family to "continue to fight this fight." To prison officials Davis said, "may God have mercy on your souls. May God bless your souls."

Davis was declared dead at 11:08 p.m. The lethal injection began about 15 minutes earlier, after the Supreme Court rejected an 11th-hour request for a stay.

Davis was originally scheduled to be put to death by lethal injection at 7 p.m., but the execution was delayed more than four hours while the High Court reviewed his case. The justices issued a ruling that blocked a reprieve after 10 p.m.

"Troy Davis has impacted the world," his sister, Martina Correia, said at a news conference, according to the Associated Press. "They say, 'I am Troy Davis,' in languages he can't speak."

Davis's case sparked numerous protests around the world as his supporters decried his 1991 death row conviction for the murder of off-duty Georgia police officer MacPhail.

Following the Georgia pardon and parole board's denial of clemency Tuesday, the NAACP and Amnesty International gathered on the steps of the Georgia State Capitol to rally in support of Davis and condemn the board’s decision. Both organizations asked supporters to keep pressure on District Attorney Larry Chisolm and ask that he stop the execution and they have planned additional protests and vigils ahead of the execution.

His supporters worked tirelessly to prevent the execution. Amnesty International said they collected nearly one million signatures on a petition on Davis's behalf. "The state of Georgia is about to demonstrate why government can't be trusted with the power over life and death," said Laura Moye of Amnesty International before Davis was put to death. She told the Associated Press the execution would be "the best argument for abolishing the death penalty."

His supporters included NAACP President Benjamin Todd Jealous, former President Jimmy Carter, Pope Benedict XVI, many politicians and celebrities. Rapper Big Boi, of the Atlanta-based group Outkast, threw his support behind Davis. "I'm trying to bring the word to the young people: There is too much doubt," he said at a church near the prison, the AP writes.

Earlier in the day, President Obama refused to weigh in on the pending execution. White House Press Secretary Jay Carney said it would not be appropriate for the president of the United States to weigh in on specific cases like this one, which is a state prosecution.

Davis was convicted in 1991 of killing MacPhail, who was working off-duty as a security guard at the time. MacPhail had been helping a homeless man whom prosecutors said Davis was beating with a gun after asking him for a beer. No gun was ever found, but shell casings were linked to an earlier shooting for which Davis was convicted.

His conviction rested solely upon eyewitness testimony and all but two of the original non-police witnesses have recanted or contradicted their testimony implicating Davis as the shooter. Davis’s defense and advocates in support of Davis say that there exists too much doubt over whether Davis actually committed the crime.

"Such incredibly flawed eyewitness testimony should never be the basis for an execution," Stephen Marsh, Davis’s attorney, told the Associated Press. "To execute someone under these circumstances would be unconscionable."

That argument holds no sway with MacPhail's family and prosecutors.

"He has had ample time to prove his innocence," said MacPhail's widow, Joan MacPhail-Harris. "And he is not innocent."

(Photo: AP Photo/The Savannah Morning News)