BREAKING NEWS: Georgia executes Troy Davis after his last pleas fail

JACKSON, Ga. — Georgia inmate Troy Davis was put to death by lethal injection late Wednesday for the 1989 murder of an off-duty police officer, after convincing thousands but not the justice system of his innocence.

Davis' death came after a three-hour hold while the Supreme Court considered a late request for a stay, but in the end the court refused to stop the execution, despite calls for clemency from former President Jimmy Carter, Pope Benedict XVI and others.

Although Davis' attorneys say seven of nine key witnesses against him recanted all or parts of their testimony, state and federal judges repeatedly ruled against granting him a new trial.

Dozens of demonstrators protested outside the Jackson prison, where officers were prepared for any disruptions.

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.

Hundreds of Davis supporters had gathered outside the prison in Jackson and lined a nearby highway. Crowds cheered and sang "We Shall Overcome" as news of the lethal-injection delay spread. Police in full riot gear were on hand to deal with any possible disturbance if the execution goes ahead.

But as the minutes, then hours, passed, the crowd dwindled to about 50.

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.

Davis was convicted in the 1989 slaying of off-duty Savannah police officer Mark MacPhail.

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 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 that houses Georgia's death row, about 100 people, 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.

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.

Davis' execution has been stopped three times since 2007, but on Wednesday the 42-year-old appeared to be out of legal options. 

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 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.

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.