Texas carried out the death penalty against the oldest prisoner sentenced to death, 30 years after he was convicted of murder.
Carl Buntion, 78, received a lethal injection at Huntsville Prison and was officially pronounced dead 15 minutes later, state prison authorities said.
Pontion said, in his last words, "I feel sorry for what I did, I'm ready to die" and the victim's family as well as a policeman were present during the execution.
Conservative Texas is the most executed state in the country, but someone can only be sentenced to death if the jury finds it poses a future threat to others
Pontion, who was convicted 13 times and paroled for sexually assaulting a child, and during an intervention for a regular traffic violation in Houston, Pontion shot and killed a policeman.
Pontion was later sentenced to death, but the sentence was overturned in 2009 by the state's Supreme Court, which ruled that the jury had not properly heard the defense team, but in 2012 he was sentenced to death again.
Pontion has been in solitary confinement for 23 hours a day for 20 years.