Convicted murderer Byron Black was put to death by lethal injection Tuesday, Aug. 5, in what experts believe is the first execution of a death row inmate with a working heart-regulating device.

Byron Black, a death row inmate convicted of killing his girlfriend and her two young daughters, is scheduled to be executed this morning.

Tennessee executed death row inmate Byron Black on Tuesday despite raised concerns about his implanted heart device, which could cause a "prolonged and torturous execution."