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A Georgia woman who was executed despite a plea for mercy from Pope Francis sang "Amazing Grace" until she was given a lethal injection, witnesses said.

Kelly Renee Gissendaner, who graduated from a theology program in prison, was put to death at 12:21 a.m. Wednesday after a flurry of last-minute appeals failed.

Gissendaner, who was sentenced to death for the 1997 stabbing murder of her husband at the hands of her lover, sobbed as she called the victim an "amazing man who died because of me."

She was the first woman executed in Georgia in 70 years and one of a handful of death-row inmates who were executed even though they did not physically partake in a murder.

The mother of three was nearly executed in February, but the lethal injection was abruptly called off because the chemicals appeared cloudy.

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After a new execution date was set, Gissendaner, 47, convinced the Georgia Board of Pardons and Paroles to reconsider her application for clemency.

In an extraordinary turn, Pope Francis — who called for a global ban on the death penalty during his U.S. visit last week — urged the board to spare her life.

“While not wishing to minimize the gravity of the crime for which Ms. Gissendander has been convicted, and while sympathizing with the victims, I nonetheless implore you, in consideration of the reasons that have been expressed to your board, to commute the sentence to one that would better express both justice and mercy,” Archbishop Carlo Maria Vigano wrote on the pontiff's behalf.

Shortly thereafter, the board announced that it would not stop the execution.

The victim's family was split on whether Gissendaner should live or die: Her children appeared before the parole board to ask that their mom be spared the death chamber, but her husband's relatives said she did not deserve clemency.

"Kelly planned and executed Doug’s murder. She targeted him and his death was intentional," Douglas Gissendaner's loved ones said in a written statement.

"In the last 18 years, our mission has been to seek justice for Doug’s murder and to keep his memory alive. We have faith in our legal system and do believe that Kelly has been afforded every right that our legal system affords.

"As the murderer, she’s been given more rights and opportunity over the last 18 years than she ever afforded to Doug who, again, is the victim here. She had no mercy, gave him no rights, no choices, nor the opportunity to live his life. His life was not hers to take."

Doug Gissendaner Family photo via WXIA

In the hours before her death, Gissendaner pressed a number of appeals, arguing that it was not fair she got death while the lover who killed her husband got a life sentence. She also said the execution drugs might be defective, and that she had turned her life around and found religion while in prison.

She requested her final meal last week: cheese dip with chips, Texas fajita nachos and a diet frosted lemonade.

Jeff Hullinger, a journalist with NBC station WXIA who witnessed the execution, later told reporters that Gissendaner appeared "very, very emotional, I was struck by that."

He added: "She was crying and then she was sobbing and then broke into song as well as into a number of apologies ... When she was not singing, she was praying."