Update — June 18, 2014, 7:50 p.m. ET:
John Henry, 63, was executed at the Florida State Prison on Wednesday for killing his estranged wife and her 5-year-old son in 1985.
Update — 6:50 p.m.: Supreme Court denies stay:
If the execution goes ahead as planned, Henry will be the sixth person to be executed by Florida this year, and the 28th person since 2005. He also will be the 23rd person executed in the U.S. this year.
The 11th Circuit Court of Appeals in Atlanta late Tuesday rejected Henry's request for a stay of execution on the grounds that he is mentally disabled and should not be put the death under the constitutional ban on cruel and unusual punishment.
As the Florida Supreme Court also rejected his request for a stay last week, the U.S. Supreme Court is likely the only institution that could stop Henry's execution. On Wednesday, Henry asked the Supreme Court to hear his case rejected by the 11th Circuit and to put a stay on his execution while the court considers his appeal.
Henry's attorneys have said that their client suffers from a low IQ owing to an "abhorrent childhood, extensive personal, and family mental health history, poor social adjustment, and lack of rational thinking and reasoning skills." They have expressed concerns about his mental ability to comprehend his death sentence.
However, a panel of experts appointed by the governor in May concluded that Henry did not suffer from a psychiatric illness or intellectual disability and that he understood the nature and effect of the death penalty and why the sentence had been imposed on him.
In May, the 5th Circuit Court of Appeals halted the execution of Texas inmate Robert James Campbell on the grounds that he was intellectually disabled and therefore constitutionally ineligible for the death penalty.
John Henry's execution is scheduled hours after two men from Georgia and Missouri became the country's first prisoners to be executed since Oklahoma botched the killing of an inmate in April raising nationwide concerns about the secrecy surrounding death penalty protocols in states.
Florida was the first state to use the drug midozolam in a three-drug protocol that came under scrutiny after the prolonged death of William Happ — the first person to be executed by the new procedure. Despite a bipartisan death penalty committee's recommendation to adopt a one-drug protocol, Gov. Rick Scott is not reconsidering Florida's three-drug procedure.
Henry has been on the death row for 27 years. In 1983, he was on parole after serving seven years for killing his 28-year-old common-law wife, Patricia Roddy. In December 1985, Henry stabbed his wife Suzanne Henry 13 times in the neck and face, killing her, after they had an argument about him living with another woman. Henry then took Eugene Christian, Suzanne's 5-year-old son from a previous relationship, and drove around for nine hours, smoking crack cocaine at times, before fatally stabbing him five times in the neck as the boy sat on his lap. He later told therapists that he had killed the child to reunite him with his mother.
Psychiatrists at the trial testified that Henry had a low IQ, suffered from chronic paranoia, and smoked crack cocaine.