Huntsville, Texas - A Texas man was put to death by lethal injection on Tuesday evening for the murders of teenage twin sisters, despite claims that he was intellectually disabled.

Before he was executed in the state penitentiary in Huntsville, 61-year-old Garcia White apologized to his victims' family. He was pronounced dead at 6:56 PM local time.

A former high school football star, White was convicted in 1996 of stabbing Annette and Bernette Edwards to death in December 1989.

According to court and prison records, White killed the mother, Bonita Edwards, of the 16-year-old girls following an argument at their Houston home and then murdered the two sisters.

White was not tried for the death of Bonita Edwards or for two other murders he confessed to committing, one in 1989 and another in 1995.

White's lawyers had filed a last-minute request for a stay of execution with the US Supreme Court, arguing that he was intellectually disabled and not eligible for the death penalty.

"I would like to apologize for all the wrong I have done, and for pain I've caused to the Edwards family," White said before the execution, the Texas Department of Criminal Justice said in a statement. "I regret, I apologize, and I pray that you can find peace."

Texas has carried out four executions this year and another inmate, Robert Roberson, is scheduled to be put to death on October 17, despite widespread belief in his innocence.

Lawmakers in Texas, medical experts, and best-selling novelist John Grisham are among those pushing to save Roberson life.

Four executions were carried out in the US last week and one the week before, bringing the total this year to 18.