A man executed on Tennessee death row had “sustained cardiac activity” for nearly two minutes after being declared dead, according to his attorney. The incident raises questions about how the execution was carried out and will increase scrutiny on capital punishment in Tennessee. During the lethal injection, witnesses reported that the inmate, Byron Black, started breathing and sighing loudly, and then groaned in agony before being pronounced dead 10 minutes later. An electrocardiogram showed continued heart activity for over a minute after death was declared, suggesting that the sedative pentobarbital may not have worked as intended.
Source: https://www.theguardian.com/us-news/2025/oct/24/tennessee-execution-byron-black-cardiac-activity