After the execution of Byron Black on Aug. 5, witnesses are slated to speak at a news conference outside the prison.

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."

On Tuesday morning, 69-year-old Bryon Black was put to death by lethal injection at the Riverbend Maximum Security Institution in Nashville for murdering his girlfriend, 29-year-old Angela Clay, and her daughters, 9-year-old Latoya and 6-year-old Lakeisha.