Singing "Amazing Grace" moments before she breathed her last, a female convict was executed by the state of Georgia on Wednesday despite efforts by Pope Francis himself to save her.

Kelly Renee Gissendaner sang the famous Christian song moments before she was given lethal injection at 12:21a.m., according to NBC News.

She was sentenced to death for the murder of her husband in 1997 by her lover.

Gissendaner was the first woman executed in Georgia in 70 years and was one of those who were executed despite that they did not physically carry out the killings.

She was nearly executed last February but it was called off because the chemicals appeared to be cloudy.

When a new date was announced, she pleaded with the Georgia Board of Pardons and Paroles to grant her application for clemency.

During his US visit, Pope Francis called for a ban on death penalty worldwide and specifically urged US authorities to stop Gissendaner's execution.

"While not wishing to minimise the gravity of the crime for which Ms. Gissendander has been convicted, and while sympathising 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 said on the Pope's behalf.

However, the board rejected the plea.

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 family said in a written statement.

They added, "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."