South Carolina executed Richard Moore on Friday for the 1999 shooting death of a convenience store clerk.

Moore, 59, was executed by lethal injection after making a number of unsuccessful arguments to Republican Gov. Henry McMaster and the U.S. Supreme Court, among others. He was the last Black man on South Carolina's death row to be convicted and sentenced by an all-white jury, according to his attorney.

Not only does the death sentence imposed by an all-white jury raise serious questions about whether Moore got a fair shake in South Carolina's court system, his attorney argues that Moore was unarmed when he walked into the convenience store and wasn't even there to rob it.

"This isn’t the worst of the worst," his attorney, Lindsey Vann, told USA TODAY, this week. "This isn’t the premeditated cold-blooded killing you think of when you think of the death penalty."

After the execution, his legal team at Justice 360 said in a statement that Moore's execution "underscores the flaws in South Carolina’s death penalty system."

"Who is executed versus who is allowed to live out their lives in prison appears to be based on no more than chance, race, or status," they said. "It is intolerable that our State metes out the ultimate punishment in such a haphazard way."

Here's what you need to know about Friday's execution.

What was Richard Moore convicted of?

Moore was convicted of fatally shooting James Mahoney on Sept. 16, 1999, at Nikki’s Speed Mart in Spartanburg, a city in northern South Carolina.

At trial, prosecutors told jurors that Moore confronted Mahoney with the intent to rob Nikki's, even though he was unarmed, according to coverage of the trial from the Greenville News, part of the USA TODAY Network.

It was Mahoney who drew a .45-caliber gun, after which Moore overpowered and disarmed him. Moore then shot a customer, Mahoney drew another gun, and a shootout ensued, prosecutors said. Mahoney was killed and Moore was hit in the left arm, the Greenville News reported.

Moore ended up leaving the store with $1,400 in cash after dripping blood on Mahoney while stepping over him, and then tried to buy crack cocaine at a nearby home, prosecutors said.

Moore's attorney argues that he wasn't robbing the store and a confrontation only arose after Moore was pennies short of being able to pay for his purchases and refused to leave the store.

Moore said recently that he was praying for forgiveness from Mahoney's family.

"I hate it happened. I wish I could go back and change it," a tearful Moore said as part of his request for clemency to the governor. "I took a life. I took someone's life. I broke a family."

Who is Richard Moore?

"Richard is a devoted Christian father, grandfather, and friend to many, who has reformed his life in the 25 years since his arrest," his attorney, Lindsey Vann, wrote in his clemency petition. "Like anyone who grows in their walk with Christ, Richard recognized the sins of his past and has sought forgiveness for his mistakes and how they hurt others."

Moore's two children, who are now in their 30s, said in a clemency video that he was a good father to them despite being behind bars since then were 4 and 6 years old.

"I have only ever known my dad as a great father," his daughter, Alexandria Moore, said in Moore's clemency request to McMaster. "That's the only picture I have of him, as giving me copious amounts of love, he has never made me feel anything but incredibly loved and special and I'm grateful for that."

Back when the crime happened, Vann said in the clemency petition that Moore "was a man who loved his family and wanted to support them, but who also struggled with a drug addiction that had plagued him since his teenage years growing up outside of Detroit, Michigan."

She said that addiction cost Mahoney's life and Moore's freedom but that Moore "was finally able to break free" of his addiction in prison and led a good, clean life behind bars.

During the penalty phase of Moore’s trial, prosecutor Trey Gowdy told jurors that Moore had repeatedly assaulted multiple women over the years and had previously been convicted on weapons and burglary charges in the 1980s.

Michelle Crowder testified that Moore punched her in the neck in 1991 and kicked her repeatedly in the head and back as he tried to steal her purse. He then severely beat her fiancé, who had come to her rescue, she testified.

"He's had chance after chance after chance," Gowdy said. "James Mahoney had no chance."

In Justice 360's statement following the execution, Moore's legal team said that "South Carolina needlessly took the life of ... a loving father and grandfather, a loyal friend, and a devoted follower of Christ."

"The State eliminated a glowing example of reform and rehabilitation," they said. "By killing Richard, the State also created more victims. Richard’s children are now fatherless, and his grandchildren will have to grow up without their 'Pa Pa.'"

Others who requested reprieve for Richard Moore

Among those who believe Moore's life should have been spared in favor of life in prison include his trial judge, two jurors and the former director of South Carolina's corrections department, according to Moore's clemency package to McMaster.

"He's a changed man," wrote Jon Ozmint, who believes in the death penalty and is the former director of the South Carolina Department of Corrections, which carries out the state's executions.

Retired Circuit Court Judge Gary Clary, who imposed the death sentence, also asked McMaster to grant clemency "as an act of grace and mercy."

McCaster denied the clemency request late Friday without providing an explanation. Moore was executed shortly afterward.

Contributing: Tom Langhorne, Terry Benjamin II