Updated

A Texas inmate convicted of masterminding the shooting deaths of his mother and brother is scheduled for lethal injection Thursday but could be spared after the state’s parole board unanimously voted for clemency.

In a rare recommendation, the Texas parole board endorsed a “lesser penalty” for Thomas “Bart” Whitaker, 38, who plotted the death of his family at their suburban Houston home in 2003. Whitaker’s father, Kent, was also shot in the attack but survived and said he has forgiven his son.

Since Bart's conviction, the elder Whitaker has fought hard to make sure his son lives.

Thomas Whitaker father

Thomas Whitaker's father, Kent, fought to see his son live, despite his son's conviction for masterminding the death of Kent's wife and younger son. (Reuters)

“I don’t think he’s going to believe it,” Kent Whitaker said after learning of the parole board’s unanimous decision Tuesday, KHOU reported. “We knew that the odds were that we would lose this, but honestly, I never contemplated a unanimous decision.”

Now, it’s in the hands of Republican Gov. Greg Abbott, who has just over 24 hours to either approve the parole board’s decision or grant a 30-day reprieve to review the case. Whitaker’s execution by lethal injection is planned for 6 p.m. Thursday.

It’s unclear whether Abbott will accept or reject the recommendation.

Whitaker was put on death row after being convicted of masterminding the plot that left his mother Tricia, 51, and brother Kevin, 19, dead.

His father, a 69-year-old devout Christian and retired construction company executive, said if the death penalty was implemented, it would only intensify his pain. Kent said he's seen "too much killing already" and believes his son is a changed person.

In the clemency petition, Whitaker's attorneys said his execution would "permanently compound" his father's suffering and grief, and compared the case to the biblical story of Cain and Abel, where God sent Cain to "restlessly wander" after killing his brother.

At his trial, Bart Whitaker said he took "100 percent" responsibility for planning and carrying out the killings. Prosecutors said he hated his parents and hoped to collect an inheritance.

Evidence showed the murder plot included two of Whitaker's friends and was at least Whitaker's third attempt to kill his family. The shooting was made to look like an interrupted burglary at the family's home in Sugar Land, southwest of Houston, and Bart Whitaker was shot in the arm to draw attention away from him.

About six months after the shootings, he disappeared. A year later, he was apprehended in Mexico.

The gunman, Chris Brashear, pleaded guilty in 2007 to a murder charge and was sentenced to life in prison. Another man, Steve Champagne, who drove Brashear from the Whitaker house the night of the shootings, took a 15-year prison term in exchange for testifying at Whitaker's trial.

On Tuesday, Fort Bend County District Attorney John Healey, whose office prosecuted Whitaker and convinced a jury to convict him and send him to death row, said the parole’s decision was “wrong.”

The last time the parole board voted to take someone off death row was in 2007. It would be extremely rarely for the governor to go against the parole board’s decision.

"This is Texas. This doesn't happen and I am just so encouraged that the system has worked, this was the right thing, the right thing to do," Kent Whitaker said.

The Associated Press contributed to this report.