Tennessee has carried out the United States' 19th execution of the year, killing 75-year-old death row inmate Oscar Smith for the murder of his estranged wife and her two teenage sons in 1989.

Oscar Franklin Smith, 75, was executed by lethal injection on Thursday morning for the 1989 murders of his estranged wife, Judith Smith, and her sons, Jason and Chad Burnett.

Tennessee has carried out the United States' 19th execution of the year, killing 75-year-old death row inmate Oscar Smith for the murder of his estranged wife and her two teenage…