A Georgia man convicted of murdering an off-duty prison guard 22 years ago was executed by lethal injection Friday evening.

The lawyers for Robert Butts Jr., 40, launched a last-minute appeal Friday with the U.S. Supreme Court but were rejected.

Butts twitched briefly as the lethal injection flowed into his body and groaned, "It burns, man."

He was declared dead by a prison warden at 9:58 p.m. after the compounded barbiturate pentobarbital was injected into his body. Prison officials said he had declined to take a sedative.

Strapped to a gurney with his arms out to his sides, Butts kept his eyes closed throughout the procedure. A tube that delivers the killing drugs through a wall appeared to pulse soon after the warden left the death chamber at 9:42.

His feet, in white socks visible under a blanket, briefly twitched. He yawned, then a short time later, opened his mouth again, noiselessly. His chest rose high as his back arched. Then he took about nine deep breaths, and after that, he lay still.

The State of Georgia argued that Butts had been justly convicted and faced a fair sentence.

Butts was the second inmate put to death in Georgia this year, and 10th overall in the United States.

According to court records, Butts and his accomplice, Marion Wilson, had asked Donavan Parks, 25, for a ride at a local Walmart in southeast Atlanta in 1996. Parks obliged.

Later, Wilson pulled Parks out of the car by his tie before Butts shot him in the back of a head with a sawed-off shotgun, court records say. After failing to sell the car at a pawn shop, Butts and Wilson set the car on fire.

Butts’ lawyers argued against the death sentence, and insisted that Wilson, not Butts had been the shooter, the Atlanta Journal-Constitution reported. The lawyers cited jail house informants who claimed Butts had told them he had not murdered Parks.

According to a clemency petition, two of Butts’ cell mates admitted to lying when they said he had confessed to the murder.

The lawyers’ last-minute launching of an appeal on Friday with the U.S. Supreme Court was rejected. The State of Georgia argued that Butts had been justly convicted and faced a fair sentence.

Butts was the second inmate put to death in Georgia this year, and 10th overall in the United States.

Wilson, who has also been sentenced to death, is appealing his case.

The Associated Press contributed to this story.