KENT Whitaker is the sole survivor of an ambush set up by his son Thomas that saw the rest of their family murdered in 2003.
Thomas Whitaker lured his family out to dinner by saying he had graduated from a college that it turns out he never attended while his friend Chris Brashear lay in wait to kill the family at their Texas home.
When they returned from their dinner, Thomas Whitaker, then known as Bart, made an excuse about having to get his mobile phone from his car as the rest of the family entered the home.
His brother, Kevin Whitaker was shot first and died as he fell. Their mother, Tricia Whitaker, was then shot and later died as she was flown to hospital.
Kent Whitaker was also shot but managed to survive. Thomas was shot in the arm in an attempt to be seen as a victim.
It took over a year for police to work out that Thomas was the mastermind of the crime, during which he lived with his father and seemingly grieved for their lost loved ones.
He then fled to Mexico where he lived for a year under a false named before he was arrested and extradited back to the US.
He was convicted and is scheduled to be executed by lethal injection on February 22.
However, Kent has written a heartfelt letter to Texas Governor Greg Abbott, obtained by the American Statesman, asking for him to commute the sentence to life in prison.
"I have seen too much killing already ... I don't want to see him executed right there in front of my eyes," he wrote. "I know Tricia and Kevin would not want him to be executed. I can't imagine seeing the last living part of my family executed by the state, especially since all the victims didn't want that to happen in the first place."
He says the prosecution's argument that Thomas believed he would inherit $US1 million was wrong and that he actually had an unrecognised mental health illness.
He has also included letters from other inmates showing how his son, now 38, has turned his life around.
"Thomas provides care packages to newly arrived inmates - a toothbrush, razor, coffee packets, chips - because commissary privileges take a while to set up," Kent said, according to the Statesman.
He says his son also helps other inmates with mental health illness.
Kent, who visits Thomas regularly in prison, says his new wife Tanya, has also come to love his murderous son.
Thomas has received a bachelor's degree in prison and is close to earning a master's degree in English literature
"His master's thesis is in committee. It won't be finished until well after February 22, but his adviser has assured both of us that regardless of what happens, it will be approved and the master's of literature degree will be bestowed to him," Kent wrote.
Kent says whatever the outcome of his clemency plea he will be on-hand to see his son in his final moments.
"As he goes to sleep, I want him to be able to look at me and see that I love him. I really want him to know that I forgive him, that I love him," he said. "Tanya will be there too, and he'll see the same thing in her eyes.
"I don't want to see this. God, I don't want to see this. I've seen enough killing. But I can't imagine letting him be in the room by himself without anyone there with him."
Update your news preferences and get the latest news delivered to your inbox.