Georgia has carried out the first execution in the US since a botched lethal injection of an Oklahoma prisoner in April.
Officials in Oklahoma halted the execution of Clayton Lockett in April after he began making noises. He died of a heart attack less than an hour later.
Marcus Wellons, who raped and killed a 15-year-old in 1989, was executed by lethal injection on Tuesday after a last-minute appeal to the US Supreme Court was denied.
Shortly afterwards John Winfield, 46, was executed by lethal injection in Missouri for killing two women.