“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."
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.
Tracy Connor is a senior writer for NBC News. She started this role in December, 2012. Connor is responsible for reporting and writing breaking news, features and enterprise stories for NBCNews.com. Connor joined NBC News from the New York Daily News, where she was a senior writer covering a broad range of news and supervising the health and immigration beats. Prior to that she was an assistant city editor who oversaw breaking news and the courts and entertainment beats.
Earlier, Connor was a staff writer at the New York Post, United Press International and Brooklyn Paper Publications.
Connor has won numerous awards from journalism organizations including the Deadline Club and the New York Press Club.
She lives in Brooklyn, N.Y.
Gabe Gutierrez is an NBC News Correspondent based in Atlanta, Georgia. He reports for all platforms of NBC News, including "TODAY," “NBC Nightly News," MSNBC and NBCNews.com.