Byron Black, a Tennessee man convicted of a 1988 triple homicide, was executed by lethal injection Tuesday morning despite legal challenges citing his mental health and concerns that his implantable heart device could cause unconstitutional suffering during the procedure, according to reports.

Black, 69, was put to death at Riverbend Maximum Security Institution in Nashville, according to the Tennessee Department of Correction. He was pronounced dead at 10:43 a.m., with no final words, said Department of Correction Commissioner Frank Strada.

Seven media witnesses reported that Black showed visible signs of distress after the drug pentobarbital was administered. He appeared to be breathing deeply and told his spiritual adviser, "it hurts so bad." The adviser replied, "I'm so sorry." Witnesses noted that during Tennessee's previous execution using the same drug, inmate Oscar Smith did not show such signs of pain.

Media members also observed that Black's hands and legs were restrained and wrapped, with his lower body covered by a blanket. While they did not see him physically react in a pronounced way, some suggested his reported pain could indicate suffering.

Kelley Henry, one of Black’s attorneys, said it was not immediately clear whether the pain came from the effects of pentobarbital or his implantable cardioverter defibrillator (ICD).

 "I interpret that my client was tortured today," she said, adding that a full review and autopsy would follow.

Black’s legal team had petitioned the U.S. Supreme Court for a stay of execution, arguing that he was mentally incompetent, and that activating his ICD during the process could violate the Eighth Amendment's ban on cruel and unusual punishment. Neither the Supreme Court nor Governor Bill Lee intervened.

Just weeks prior, a Davidson County Chancery Court had ruled that Black's device should be deactivated prior to the execution, siding with his attorneys who argued the ICD might shock his heart back into rhythm mid-execution. But the Tennessee Supreme Court overturned that decision, stating that the lower court lacked the authority to delay the sentence, though it left open the possibility of voluntary deactivation by the state.

Still, Attorney General Jonathan Skrmetti pushed forward, denying Black’s intellectual disability and minimizing concerns over pain. “Our office will continue fighting to seek justice for the Clay family,” he said.