Texas executed the oldest person on death row, a 78-year-old man convicted of killing a police officer more than 30 years ago, reports AFP.

Lawyers for Carl Buntion filed a final appeal to the US Supreme Court seeking a stay, but it was denied. According to the Texas Department of Criminal Justice, he was executed by lethal injection and declared dead at 6:39 p.m. local time.

Buntion was the oldest death row inmate in Texas, a conservative southern state that executes more prisoners than any other American state.

In June 1990, he shot and killed Houston police officer James Irby. At that time, he already had a criminal record and was released on parole after being convicted of sexually abusing a minor.

Buntion was executed with a lethal dose of pentobarbital and died 13 minutes after it was administered, the state Department of Criminal Justice said.