The state of Georgia Wednesday night executed Troy Davis, who was convicted of killing an off-duty Savannah police officer 22 years ago, after the U.S. Supreme Court rejected a last-minute appeal for a stay.

Davis, 42, was executed at 11:08 p.m. ET, four hours after he was scheduled to receive the lethal injection Wednesday at 7 p.m., The New York Times reported. His execution was delayed while the Supreme Court reviewed the stay request.

Davis spent his last few hours with his family. Police in riot gear stood by while his supporters gathered outside the prison entrance. He didn't choose a last meal. 

We're calling on everyone to stay calm, Benjamin T. Jealous, president of the NAACP, told The New York Times.

Davis’ lawyers and supporters appealed to various state and federal courts to stop the execution but were rebuffed, and Davis' last option seemed lost when the Georgia Board of Pardons and Parole rejected his request to take a polygraph test and the Georgia Supreme Court refused to stay the execution or to commute his death sentence to life in prison without parole.

Thousands of people opposing the execution gathered outside the prison but there were some counter-protestors, including the family of Officer Mark MacPhail, the murder victim. MacPhail’s family told reporters that they believed Davis was guilty and he should be executed.

Earlier Anneliese MacPhail, the slain cop's mother, told CNN, I will never have closure. But I may have some peace when he is executed.

Davis, who was 19 years old when he was arrested for the murder of MacPhail, has always professed his innocence in the 1989 shooting. MacPhail, 27, was working as a security officer outside a Savannah bus station on Aug. 19 when shot as he tried to break up a fight.

No physical evidence was presented against Davis during his trial, and multiple witnesses have recanted or changed their testimony in the years since the murder.

Davis' execution gained international attention and more than 630,000 people signed petitions urging clemency. Davis received support from Amnesty International and the National Organization for the Advancement of Colored People, as well as from an array of prominent political and religious figures, including former President Jimmy Carter, Pope Benedict XVI, Archbishop Desmond Tutu, the Rev. Al Sharpton and former FBI Director William Sessions. 

Justice was finally served for my father, said Mark MacPhail Jr., who was an infant when his father was gunned down. The truth was finally heard.